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  • 101.
    Dai, Daoxin
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    He, S L
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Calculation of the spectral response of an arrayed-waveguide gating demultiplexer with a wide-angle beam propagation method in a cylindrical coordinate system2004Ingår i: Optical and quantum electronics, ISSN 0306-8919, E-ISSN 1572-817X, Vol. 36, nr 11, s. 967-979Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The spectral response of an arrayed-waveguide grating (AWG) demultiplexer is calculated by simulating the field propagation in the output section of an AWG with a wide-angle beam propagation method (BPM) in a cylindrical coordinate system. As in a practical design of an AWG demultiplexer, each output waveguide consists of two straight sections connected by a bending section. The spectral response obtained by the present algorithm is more accurate than those obtained with two popular approximate methods, namely, the conventional overlapped integral method and the standard BPM for radially straight and infinitely long output waveguides. With the present algorithm, the dependence of the spectral response on the parameters of the output section is analyzed. The channel crosstalk and the 3 dB passband width of the spectral response depend mainly on the length of the first straight section, the end separation and the angular separation of the output waveguides. The bending section results in an asymmetrical spectral response with remarkable sidelobes which can be reduced by increasing the bending radius.

  • 102. Dai, Daoxin
    et al.
    He, Sailing
    A silicon-based hybrid plasmonic waveguide with a metal cap for a nano-scale light confinement2009Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 17, nr 19, s. 16646-16653Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A hybrid plasmonic waveguide with a metal cap on a silicon-on-insulator rib (or slab) is presented. There is a low-index material nano-layer between the Si layer and the metal layer. The field enhancement in the nano-layer provides a nano-scale confinement of the optical field (e. g., 50nm x 5nm) when operates at the optical wavelength lambda = 1550nm. The theoretical investigation also shows that the present hybrid plasmonic waveguide has a low loss and consequently a relatively long propagation distance (on the order of several tens of lambda).

  • 103.
    Dai, Daoxin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    Accurate two-dimensional model of an arrayed-waveguide grating demultiplexer and optimal design based on the reciprocity theory2004Ingår i: Journal of the Optical Society of America A: Optics and Image Science, and Vision, ISSN 1084-7529, Vol. 21, nr 12, s. 2392-2398Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An accurate two-dimensional (2D) model is introduced for the simulation of an arrayed-waveguide grating (AWG) demultiplexer by integrating the field distribution along the vertical direction. The equivalent 2D model has almost the same accuracy as the original three-dimensional model and is more accurate for the AWG considered here than the conventional 2D model based on the effective-index method. To further improve the computational efficiency, the reciprocity theory is applied to the optimal design of a flat-top AWG demultiplexer with a special input structure.

  • 104.
    Dai, Daoxin
    et al.
    KTH, Tidigare Institutioner                               , Alfvénlaboratoriet.
    He, Sailing
    KTH, Tidigare Institutioner                               , Alfvénlaboratoriet.
    Analysis of characteristics of bent rib waveguides2004Ingår i: Journal of the Optical Society of America A, ISSN 0740-3232, Vol. 21, nr 1, s. 113-121Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    With a perfectly matched layer boundary treatment, a semivectorial finite-difference method is used to calculate the eigenmodes of a single-mode (SM) or multimode (MM) bent rib waveguide. A detailed analysis is given for the dependence of the bending losses (including the pure bending loss and the transition loss) on geometrical parameters of the bent rib waveguide such as the rib width, the rib height, and the bending radius. The characteristics of the higher-order modes are analyzed. It is shown that the bending loss of the fundamental mode can be reduced effectively by increasing the width and height of the rib. For an integrated device, undesired effects due to the higher-order modes of a MM bent waveguide can be removed by appropriate choice of the geometrical parameters. An appropriately designed MM bent waveguide is used to reduce effectively the bending loss of the fundamental mode, and a low-loss SM propagation in a MM bent waveguide is realized when the bending losses of the higher-order modes are large enough.

  • 105.
    Dai, Daoxin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    Analysis of the birefringence of a silicon-on-insulator rib waveguide2004Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 43, nr 5, s. 1156-1161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A detailed analysis of the polarization characteristics (birefringence) of a silicon-on-insulator (SOI) rib waveguide is given. The fundamental TE- and TM-polarized modes of the SOI rib waveguide are calculated by a semivectorial finite-difference method. The rib width and the slab height of the SOI rib waveguide are normalized with respect to the total height of the silicon layer. A general relation between the two normalized parameters for a nonbirefringent SOI rib waveguide is obtained. According to this relation a nonbirefringent SOI rib waveguide can easily be designed. The fabrication tolerance for a nonbirefringent SOI rib waveguide is also analyzed, revealing that the tolerance can be increased by use of a larger total height of the silicon layer.

  • 106.
    Dai, Daoxin
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, East Bldg 5,Zijingang Campus, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH.
    Compact silicon-based wavelength-selective photonic integrated devices and the applications2009Ingår i: SILICON PHOTONICS IV / [ed] Kubby, JA Reed, GT, SPIE-INT SOC OPTICAL ENGINEERING , 2009, artikel-id UNSP 72200DKonferensbidrag (Refereegranskat)
    Abstract [en]

    In wavelength-division multiplexing systems, it is important to develop various wavelength-selective components to have flexible and reconfigurable nodes. When using conventional optical waveguides with low index contrast, the sizes of these wavelength-selective components are usually several cm(2), which is too large to integrate more components in a single wafer or chip. In order to improve the integration density and reduce the cost, it is desirable to minimize the component sizes. In our case, two kinds of strongly-confined optical waveguides on silicon wafer are considered for compact wavelength-selective devices. One is the popular silicon-on-insulator (SOI) nanowire and the other is SU-8 strip optical waveguide with an air cladding and a SiO2 insulator layer on a Si substrate. In this paper, we give a review of our recent work on wavelength-selective photonic integrated devices based on these two kinds of silicon-based optical waveguides with strong-confinements. Arrayed-waveguide grating (AWG) and microring resonator (MRR), which are two typical wavelength-selective components are included. First we give a review for several new layouts for SOI-nanowire AWG to have a further size-reduction and our novel designs for diminishing the polarization dependency of AWGs. Secondly we present the design and fabrication of multimode interference (MMI) couplers for MRRs. A novel design method for tapered MMI couplers is presented and the diminishment of polarization in a MMI coupler is proposed by optimizing the tapered MMI section. We also present our experimental results on optical sensor combining MRRs and micro-fluid channel. The measured sensitivity is about 180nm/RIU.

  • 107. Dai, Daoxin
    et al.
    He, Sailing
    Highly sensitive sensor based on an ultra-high-Q Mach-Zehnder interferometer-coup led microring2009Ingår i: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 26, nr 3, s. 511-516Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A high-Q Mach-Zehnder interferometer (MZI)-coupled microring is presented for optical sensing with high sensitivity and a large measurement range. By optimizing the length difference, between the two arms of the MZI coupler, the MZI-coupled microring with a high-Q factor and high extinction ratio is obtained. In the present example, the Q factor of the designed silicon-nanowire-based microring is as high as 1.8 x 10(5) when the silicon nanowire has a propagation loss L=2 dB/cm. Due to this high-Q factor, the sensitivity for the change Delta n of the effective refractive index is about 10(-5)-10(-6) by measuring the shift of the resonant wavelength. Because of the wavelength dependence of the coupling ratio of the MZI coupler, it is possible to have only one resonant wavelength with a high extinction ratio in a very large wavelength span [i.e., the quasi-free spectral range of the MZI-coupler microring], which offers a very large measurement range covering the refractive index change

  • 108. Dai, Daoxin
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Highly-sensitive sensor with large measurement range realized with two cascaded-microring resonators2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 279, nr 1, s. 89-93Artikel i tidskrift (Refereegranskat)
  • 109. Dai, Daoxin
    et al.
    He, Sailing
    Optimization of ultracompact polarization-insensitive multimode interference couplers based on Si nanowire waveguides2006Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 18, nr 17-20, s. 2017-2019Artikel i tidskrift (Refereegranskat)
  • 110. Dai, Daoxin
    et al.
    He, Sailing
    Proposal of a Coupled-Microring-Based Wavelength-Selective 1 x N Power Splitter2009Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 21, s. 1630-1632Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel wavelength-selective 1 x N power splitter, which consists of a microring and N + 1 couplers, is presented. One coupler is for coupling the light signal from the input port into the microring and the other couplers are for coupling the signal light from the microring to the output ports. The channels with the resonant wavelength of the microring are dropped and split into output ports. The critical coupling condition to achieve a high extinction ratio is also given. By appropriately choosing the coupling coefficients for the input/output couplers, it is flexible to have a uniform or nonuniform power splitting as desired.

  • 111.
    Dai, Daoxin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Reduction of multimode effects in an SOI-based etched diffraction grating demultiplexer2005Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 247, nr 4-6, s. 281-290Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Multimode effects in the free propagation region (FPR) of a silicon-on-insulator (SOI)-based etched diffraction grating (EDG) demultiplexer are analyzed. In a conventional design, the power coupled to the higher order modes is considerable, which introduces a significant excess loss and crosstalk. It is shown that the multimode effects in an SOI EDG demultiplexer are much more detrimental than in an arrayed waveguide grating demultiplexer. Several methods for reducing the multimode effects are discussed. In particular, a laterally tapered structure between the FPR and the input/output waveguides is proposed as a simple and effective method for reducing the power coupled to the higher order modes and consequently reducing the multimode effects. The taper width is optimized to minimize the crosstalk.

  • 112. Dai, Daoxin
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Ultrasmall integrated devices based on silicon nanowires for optical communications2008Ingår i: JOURNAL OF NANOPHOTONICS, ISSN 1934-2608, Vol. 2, s. 021780-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Planar lightwave circuits (PLCs) based on Si nanowires exhibit several serious problems due to the small cross sections of the nanowires. These problems include large scattering loss, large coupling loss to a single-mode fiber, and high dependency on polarization. Several solutions to these problems have emerged. Recent progress on Si-nanowire-based passive PLC devices encompasses arrayed waveguide grating (de) multiplexers, microring resonators, and multimode interference couplers.

  • 113. Dai, Daoxin
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Ultrasmall overlapped arrayed-waveguide grating, based on Si nanowire waveguides for dense wavelength division demultiplexing2006Ingår i: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 12, nr 6, s. 1301-1305Artikel i tidskrift (Refereegranskat)
  • 114. Dai, Daoxin
    et al.
    Hu, Rui
    He, Sailing
    A minimized SiO2 waveguide with an antiresonant reflecting structure for large-scale optical integrations2007Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 19, nr 09-12, s. 759-761Artikel i tidskrift (Refereegranskat)
  • 115.
    Dai, Daoxin
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Liu, Liu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Three-dimensional hybrid modeling based on a beam propagation method and a diffraction formula for an AWG demultiplexer2007Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 270, nr 2, s. 195-202Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An efficient and accurate three-dimensional (3D) hybrid modeling, which combines a 3D beam propagation method (BPM) and the two-dimensional (2D) Kirchhoff-Huygens diffraction formula, is developed to simulate the field propagation in an arrayed waveguide grating (AWG) dernultiplexer. The 2D Kirchhoff-Huygens diffraction formula is used for the simulation of the light propagation in the free propagation regions (FPRs). A 3D BPM in a polar coordinate system is used to simulate the light propagation in the transition region between the input FPR and the arrayed waveguides so that the coupling coefficients for the arrayed waveguides are calculated conveniently and accurately. For the simulation in the transition region between the arrayed waveguides and the output FPR, only the central arrayed waveguide and several adjacent ones are needed in the computational window of a standard BPM and thus the computation efficiency is improved. Finally, a flat-top AWG is designed and fabricated to verify the reliability of the present simulation method. The calculated and measured spectral responses are in a good agreement.

  • 116. Dai, Daoxin
    et al.
    Shi, Yaocheng
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Characteristic analysis of nanosilicon rectangular waveguides for planar light-wave circuits of high integration2006Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 45, nr 20, s. 4941-4946Artikel i tidskrift (Refereegranskat)
  • 117. Dai, Daoxin
    et al.
    Shi, Yaocheng
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Comparative study of the integration density for passive linear planar light-wave circuits based on three different kinds of nanophotonic waveguide2007Ingår i: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 46, nr 7, s. 1126-1131Artikel i tidskrift (Refereegranskat)
  • 118.
    Dai, Daoxin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Shi, Yaocheng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Theoretical Investigation for Reducing Polarization Sensitivity in Si-Nanowire-Based Arrayed-Waveguide Grating (de)Multiplexer With Polarization-Beam-Splitters and Reflectors2009Ingår i: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 45, nr 5-6, s. 654-660Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel design for reducing polarization sensitivity in silicon-on-insulator-based arrayed-waveguide grating (AWG) (de)multiplexer is presented. Each arrayed waveguide has two sections separated by a polarization beam splitter (PBS). These two sections have different core widths and length differences. With these PBSs, one polarization is reflected and the other one goes through. The through polarization enters the second section and is then reflected by a reflector at the end of the second section of the arrayed waveguide. The theoretical simulation shows that one can diminish greatly the polarization sensitivity of both the central channel wavelength and the channel spacing by optimizing the core width and length difference of the second section. The design procedure and formulas are given and an appropriate diffraction order is chosen to obtain a good fabrication tolerance. As an example, an ultrasmall (82.2 x 85.1 mu m(2)) AWG (de)multiplexer with eight channels and a channel spacing of 4 nm is designed to have minimized polarization sensitivity and Bragg-grating PBSs and photonic crystal reflectors are used.

  • 119.
    Dai, Daoxin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Shi, Yaocheng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Thylen, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Silicon hybrid plasmonic submicron-donut resonator with pure dielectric access waveguides2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 24, s. 23671-23682Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Characteristic analyses are given for a bent silicon hybrid plasmonic waveguide, which has the ability of submicron bending (e.g., R = 500nm) even when operating at the infrared wavelength range (1.2 mu m similar to 2 mu m). A silicon hybrid plasmonic submicron-donut resonator is then presented by utilizing the sharp-bending ability of the hybrid plasmonic waveguide. In order to enable long-distance optical interconnects, a pure dielectric access waveguide is introduced for the present hybrid plasmonic submicron-donut resonator by utilizing the evanescent coupling between this pure dielectric waveguide and the submicron hybrid plasmonic resonator. Since the hybrid plasmonic waveguide has a relatively low intrinsic loss, the theoretical intrinsic Q-value is up to 2000 even when the bending radius is reduced to 800nm. By using a three-dimensional finite-difference time-domain (FDTD) method, the spectral response of hybrid plasmonic submicron-donut resonators with a bending radius of 800nm is simulated. The critical coupling of the resonance at around 1423nm is achieved by choosing a 80nm-wide gap between the access waveguide and the resonator. The corresponding loaded Q-value of the submicron-donut resonator is about 220.

  • 120.
    Dai, Daoxin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Shi, Yaocheng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium2011Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 19, nr 14, s. 12925-12936Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A theoretical investigation of a nano-scale hybrid plasmonic waveguide with a low-index as well as high-index gain medium is presented. The present hybrid plasmonic waveguide structure consists of a Si substrate, a buffer layer, a high-index dielectric rib, a low-index cladding, a low-index nano-slot, and an inverted metal rib. Due to the field enhancement in the nano-slot region, a gain enhancement is observed, i.e., the ratio partial derivative G/partial derivative g > 1, where g and G are the gains of the gain medium and the TM fundamental mode of the hybrid plasmonic waveguide, respectively. For a hybrid plasmonic waveguide with a core width of w(co) = 30nm and a slot height of h(slot) = 50nm, the intrinsic loss could be compensated when using a low-index medium with a moderate gain of 176dB/cm. When introducing the high-index gain medium for the hybrid plasmonic waveguide, a higher gain is obtained by choosing a wider core width. For the high-index gain case with h(slot) = 50nm and w(co) = 500nm, a gain of about 200dB/cm also suffices for the compensation of the intrinsic loss.

  • 121. Dai, Daoxin
    et al.
    Yang, Bo
    Yang, Liu
    Sheng, Z.
    He, Sailing
    Compact Microracetrack Resonator Devices Based on Small SU-8 Polymer Strip Waveguides2009Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 1-4, s. 254-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n similar to 1.573), a SiO2 buffer (n similar to 1.445), and an air cladding. The fabricate straight waveguide has a low propagation loss of about 0.1. dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (similar to 150 mu m) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.

  • 122. Dai, Daoxin
    et al.
    Yang, Liu
    Sheng, Z.
    Yang, Bo
    He, Sailing
    Compact Microring Resonator With 2 x 2 Tapered Multimode Interference Couplers2009Ingår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 27, nr 21, s. 4878-4883Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Compact microring resonator devices are realized by using a small SU-8 polymer strip waveguide that has an SU-8 polymer core (n similar to 1.573), an SiO2 buffer (n similar to 1.445), and an air cladding. Due to the high index contrast of the optical waveguide, a small bending radius (similar to 150 mu m) is used for the MRR. To enhance the coupling between the access optical waveguides and the microring, 2 x 2 multimode interference couplers are used. The measured spectral response of the through port shows a high extinction ratio of over 15 dB and a 3-dB bandwidth of about 0.38 nm (corresponding to a moderate Q-value of similar to 4500).

  • 123.
    Dai, Hao
    et al.
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    Yang, Liu
    Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Zhejiang, Peoples R China..
    He, Sailing
    KTH, Skolan för teknikvetenskap (SCI), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP. KTH, Skolan för elektroteknik och datavetenskap (EECS). Zhejiang Univ, Natl Engn Res Ctr Opt Instrumentat, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China.;Zhejiang Univ, Ningbo Res Inst, Ningbo 315100, Zhejiang, Peoples R China..
    < 50-mu m thin crystalline silicon heterojunction solar cells with dopant-free carrier-selective contacts2019Ingår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 64, artikel-id UNSP 103930Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dopant-free carrier-selective contacts are emerging in the field of crystalline silicon (c-Si) photovoltaic solar cells, which are potential to further improve the power conversion efficiency (PCE) and lower the cost of c-Si solar cells. Here, we demonstrate tens of microns thin c-Si heterojunction solar cells with substochiometric MoOx and LiFx as dopant-free hole- and electron-selective contacts, respectively. Chemical thinning of 200-mu m thick c-Si wafers enables the production of proof of concept devices with good flexibility and strong performance. When the wafer thickness is reduced to 49.4 mu m (24.7% of the initial thickness), the power conversion efficiency (PCE) of the solar cell still maintains 88.2% of the initial value for the 200-mu m thick cell. When the wafer thickness becomes less than 10% (or even 3.4%) of the initial value, 61.2% and 39.2% of the initial PCEs are still achieved for the 14.8- and 6.8-mu m thick cells, respectively. Passivating and carrier-selective effects of the MoOx and LiFx films allow for the maintenance of performance. An oxide interlayer at the MoOx/c-Si interface passivates the dangling bonds of the c-Si surface and improves the minority carrier lifetime. Field-effect passivation and carrier-selective effects induced by the band bending near the MoOx/c-Si interface and the Al/LiFx/c-Si interface play an important role in maintaining high open-circuit voltage and high fill factor. To the best of our knowledge, this is the first time that <100-mu m thin c-Si heterojunction solar cells are reported with undoped contacts. Our solar cells have been fabricated on thin c-Si wafers with low-temperature processes and without additional doping, and thus our work provides a promising cost-effective means in the field of thin and flexible c-Si solar cells.

  • 124. Ding, Fei
    et al.
    Cui, Yanxia
    Ge, Xiaochen
    Jin, Yi
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Ultra-broadband microwave metamaterial absorber2012Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, nr 10, s. 103506-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A microwave ultra-broadband polarization-independent metamaterial absorber is demonstrated. It is composed of a periodic array of metal-dielectric multilayered quadrangular frustum pyramids. These pyramids possess resonant absorption modes at multi-frequencies, of which the overlapping leads to the total absorption of the incident wave over an ultra-wide spectral band. The experimental absorption at normal incidence is above 90% in the frequency range of 7.8-14.7 GHz, and the absorption is kept large when the incident angle is smaller than 60 degrees. The experimental results agree well with the numerical simulation.

  • 125. Ding, Fei
    et al.
    Jin, Y.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Ultra-broadband near-infrared metamaterial absorber2012Ingår i: Asia Commun. Photonics Conf., 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    A near-infrared wide-band polarization-insensitive absorber is demonstrated. It is composed of two-dimensional titanium disk arrays and a gold plate. The absorption at normal incidence is above 90% in the range of 164.2THz to 345.2 THz.

  • 126. Ding, J. F.
    et al.
    Zhang, A. P.
    Shao, L. Y.
    Yan, J. H.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Fiber-taper seeded long-period grating pair as a highly sensitive refractive-index sensor2005Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 17, nr 6, s. 1247-1249Artikel i tidskrift (Refereegranskat)
  • 127. Ding, Jiechen
    et al.
    Hu, Jun
    Khan, Salman Naeem
    Ying, Zhinong
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    An ultra-wideband monopole antenna of small size2006Ingår i: 2006 IEEE International Workshop on Antenna Technology: Small Antennas and Novel Metamaterials (IWAT), NEW YORK: IEEE , 2006, s. 61-63Konferensbidrag (Refereegranskat)
  • 128.
    Ding, Jiechen
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    Lin, Zhili
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Hangzhou 310058, Zhejiang, Peoples R China..
    Ying, Zhinong
    Nya Vattertornet, Sony Ericsson Mobile Commun AB, SE-22183 Lund, Sweden..
    He, Sailing
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion.
    A compact ultra-wideband slot antenna with multiple frequency bands (vol 49, pg 3056, 2007)2008Ingår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 50, nr 5, s. 1446-1446Artikel i tidskrift (Refereegranskat)
  • 129. Ding, Jiechen
    et al.
    Lin, Zhili
    Ying, Zhinong
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    A compact ultra-wideband slot antenna with multiple notch frequency bands2007Ingår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 49, nr 12, s. 3056-3060Artikel i tidskrift (Refereegranskat)
  • 130. Fang, Y. T.
    et al.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Transparent structure consisting of metamaterial layers and matching layers2008Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 78, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    transparent periodic structure consisting of metamaterial (double negative) layers and matching (single negative material) layers is presented. Through the calculation of the band structure and transmission spectrum, this kind of structure is found to be omnidirectionally transparent to some electromagnetic wave of any polarization. The working frequency and bandwidth can be adjusted by changing the thicknesses of material layers.

  • 131.
    Fei, Chao
    et al.
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Hong, Xiaojian
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Zhang, Guowu
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Du, Ji
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Gong, Yu
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    Evans, Julian
    Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    He, Sailing
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Zhejiang Univ, Coll Opt Sci & Engn, Ctr Opt & Electromagnet Res, State Key Lab Modern Opt Instrumentat, Hangzhou 310058, Zhejiang, Peoples R China..
    16.6 Gbps data rate for underwater wireless optical transmission with single laser diode achieved with discrete multi-tone and post nonlinear equalization2018Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, nr 26, s. 34060-34069Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, we experimentally demonstrate a 450-nm laser underwater wireless optical transmission system by using adaptive bit-power loading discrete multi-tone (DMT) and Volterra series based post nonlinear equalization. Post nonlinear equalization mitigates the nonlinear impairment of the UWOC system. By incorporating post nonlinear equalization with a 3rd-order diagonal plane kernel, the received signal-to-noise ratio (SNR) can be improved by similar to 2 dB compared with a linear equalization method. The measured transmission capacity of the UWOC system is 16.6 Gbps over 5 m, 13.2 Gbps over 35 m, and 6.6 Gbps over 55 m tap water channel, with bit error rates (BERs) below the standard hard-decision forward error correction (HD-FEC) limit of 3.8 x 10(-3). The used electrical signal bandwidth is 2.75 GHz, corresponding to electrical spectrum efficiency of similar to 6 bit/s/Hz. The distance-datarate product reaches 462 Gbps*m at 35 m tap water transmission. To the best of our knowledge, both the data rate and distance-data rate product are the largest reported for single laser diode.

  • 132.
    Fei, Chao
    et al.
    Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Zhejiang, Peoples R China.
    Hong, Xiaojian
    Zhang, Guowu
    Ji, Du
    Wang, Yuan
    He, Sailing
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Elektroteknisk teori och konstruktion. Zhejiang Univ, Ctr Opt & Electromagnet Res, Natl Engn Res Ctr Opt Instruments, Hangzhou 310058, Zhejiang, Peoples R China.
    Improving the Performance of Long Reach UOWC With Multiband DFT-Spread2019Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 31, nr 16, s. 1315-1318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, a multiband discrete-Fourier-transform spread (DFT-spread) is introduced to reduce the peak-to-average-power ratio (PAPR) of discrete multitone (DMT)-based underwater optical wireless communication (UOWC) system. The performance of different multiband DFT-spread DMT schemes in a wide underwater transmission range (from 5 to 55 m at a fixed transmission data rate of 5.6 Gb/s) is experimentally investigated. The measured results show that the 1-band DFT-spread and 2-band DFT-spread DMT can significantly improve the system performance compared with the conventional clipping DMT, while the 1-band DFT-spread gives the best performance. Due to the single carrier frequency domain equalization-like characteristic, the 1-band DFT-spread exhibits a relatively uniform signal-to-noise ratio (SNR) profile, which shows the robustness to high frequency fading in the band-limited UOWC system. These intrinsic advantages could jointly ease the bit error rate (BER) deterioration in a long reach UOWC system. Furthermore, the measured data rate-distance product has reached 308 Gb/s*m (i.e., 55-m * 5.6 Gb/s), which to the best of our knowledge is the largest for the single modulation format.

  • 133. Fei, Z. A.
    et al.
    He, Sailing
    He, J. P.
    Feng, S. S.
    Large complete band gap of a two-dimensional photonic crystal consisting of anisotropic elliptic cylinders2002Ingår i: Wuli xuebao, ISSN 1000-3290, Vol. 51, nr 2, s. 355-361Artikel i tidskrift (Refereegranskat)
  • 134. Fei, Z. A.
    et al.
    Xiao, S. S.
    He, J. P.
    He, Sailing
    A FDTD method for calculating defect modes in a two-dimensional photonic crystal consisting of anisotropic cylinders2002Ingår i: Wuli xuebao, ISSN 1000-3290, Vol. 51, nr 9, s. 2167-2172Artikel i tidskrift (Refereegranskat)
  • 135. Feng, S. S.
    et al.
    Shen, L. F.
    He, Sailing
    A two-dimensional photonic crystal formed by a triangular lattice of square dielectric rods with a large absolute band gap2004Ingår i: Wuli xuebao, ISSN 1000-3290, Vol. 53, nr 5, s. 1540-1545Artikel i tidskrift (Refereegranskat)
  • 136. Fu, H.
    et al.
    Ou, H.
    Zhu, K.
    Remb, E.
    He, Sailing
    Zhejiang Univ. China.
    Tunable and reconfigurable microwave photonic filter implemented by cascaded mach-zehnder modulators and a dispersive medium2008Ingår i: Proceedings of SPIE - The International Society for Optical Engineering, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel tunable and reconfigurable microwave photonic filter based on two cascaded Mach-Zehnder modulators (MZMs) and a dispersive medium is presented, theoretically discussed and experimentally demonstrated. A single-wavelength laser diode (LD) and the first MZM are used to obtain a multi-wavelength optical source, and the second MZM is modulated with the signal to be processed. The dispersive medium provides the time delay for different taps, since different wavelength experiences different time delay, when it travels in the optical fiber. By adjusting the modulation frequency and the bias voltage on the first MZM, the wavelength spacing and the relative amplitude of the optical tones after the first MZM can be changed, thus making the filter tunable and reconfigurable. The presented microwave photonic filter has been implemented in the experiment. The experimental results agree well with the simulation results, and show that the present microwave photonic filter has good tunability and reconfigurability. The mainlobe-to-sidelobe ratio (MSR) of around 25dB is achieved for the presented filter in the experiment.

  • 137. Fu, H. Y.
    et al.
    Ou, H. Y.
    Zhu, K.
    Remb, E.
    He, Sailing
    A tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium2008Ingår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 281, nr 22, s. 5550-5554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel tunable and reconfigurable microwave photonic filter based on two cascaded modulators and a dispersive medium is proposed, theoretically discussed and experimentally demonstrated. A single-wavelength LD and a modulator (either a Mach-Zehnder modulator or a phase modulator which can avoid the do bias drift problem) are used to obtain a multi-wavelength optical source. By adjusting the modulation frequency and the bias voltage on the modulators, the wavelength spacing and the relative amplitude of the optical tones change, thus making the filter tunable and reconfigurable. The experimental results show that the proposed filters have good tunability and reconfigurability and the mainlobe-to-sidelobe ratio of around 25 dB is achieved.

  • 138. Fu, H. Y.
    et al.
    Zhou, K. M.
    Saffari, P.
    Mou, C. B.
    Zhang, L.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Bennion, I.
    Microchanneled Chirped Fiber Bragg Grating Formed by Femtosecond Laser-Aided Chemical Etching for Refractive Index and Temperature Measurements2008Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 17-20, s. 1609-1611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, a microchanneled chirped fiber Bragg grating (MCFBG) is proposed and fabricated through the femtosecond laser-assisted chemical etching. The microchannel (similar to 550 mu m) gives access to the external index liquid, thus inducing refractive index (RI) sensitivity to the structure. In the experiment, the transmission bands induced by the reduced effective index in the microchannel region were used to sense the surrounding RI and temperature changes. The experimental results show good agreement with the theoretical analysis. The proposed MCFBG offers enhanced RI sensitivity without degrading the robustness of the device showing good application potential as bio-chemical sensors.

  • 139. Fu, Hongyan
    et al.
    Chen, Daru
    Ou, Haiyan
    He, Sailing
    Continuously tunable incoherent microwave photonic filter using a tunable Mach-Zehnder interferometer as the slicing filter2007Ingår i: Microwave and optical technology letters (Print), ISSN 0895-2477, E-ISSN 1098-2760, Vol. 49, nr 10, s. 2382-2386Artikel i tidskrift (Refereegranskat)
  • 140.
    Fu, Hongyan
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Ou, Haiyan
    Zhu, Kun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Tunable all-optical microwave notch filter with a negative tap based on a semiconductor optical amplifier and a dispersive medium2009Ingår i: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 41, nr 3, s. 213-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A tunable all-optical microwave notch filter with a negative tap based on a semiconductor optical amplifier and a dispersive medium is demonstrated. A negative tap is realized through the cross gain modulation in the semiconductor optical amplifier. The free spectrum range of the notch filter can be tuned by tuning the wavelength of one of the two laser sources. The influence of the amplitude mismatch of the two lasers on the performance of the filter is analyzed. The present notch filter is easy to implement and cost-effective.

  • 141. Fu, Hongyan
    et al.
    Shu, X. W.
    Mou, C. B.
    Zhang, L.
    He, Sailing
    Bennion, I.
    Transversal Loading Sensor Based on Tunable Beat Frequency of a Dual-Wavelength Fiber Laser2009Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 14, s. 987-989Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microwave signal generation by using the photonic beating from a phase-shift fiber Bragg grating (PS-FBG)-based dual-wavelength laser is proposed and experimentally demonstrated. The dual-wavelength laser is formed by a linear cavity, in which a PS-FBG is used as a dual-wavelength selective component. Transversal loading on the PS-FBG enhances the birefringence of the optical fiber and consequently makes the transmission peak of the PS-FBG splitting into two sharp transmission peaks of orthogonal polarizations. The wavelength spacing between the two transmission peaks increases with the transversal loading on the PS-FBG, thus making the polarization beating frequency increase. This property is exploited in a transversal loading sensor.

  • 142. Fu, Hongyan
    et al.
    Shu, X. W.
    Suo, R.
    Zhang, L.
    He, Sailing
    Bennion, I.
    Transversal-Load Sensor by Using Local Pressure on a Chirped Fiber Bragg Grating2010Ingår i: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 10, nr 6, s. 1140-1141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A transversal-load sensor based on the local pressure-induced refractive index change in a chirped fiber Bragg grating (CFBG) is proposed. The local pressure induced refractive index change in the touch point can generate a main transmission peak and several subpeaks on the long wavelength side of the reflection band of the CFBG. The difference of the wavelength shifts for the main transmission peak and the first subpeak is used to measure transversal-load with temperature compensation capability.

  • 143. Fu, Hongyan
    et al.
    Zhang, W.
    Mou, C. B.
    Shu, X. W.
    Zhang, L.
    He, Sailing
    Bennion, I.
    High-Frequency Fiber Bragg Grating Sensing Interrogation System Using Sagnac-Loop-Based Microwave Photonic Filtering2009Ingår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 8, s. 519-521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel high-frequency fiber Bragg grating (FBG) sensing interrogation system by using fiber Sagnac-loop-based microwave photonic filtering is proposed and experimentally demonstrated. By adopting the microwave photonic filtering, the wavelength shift of sensing FBG can be converted into amplitude variation of the modulated electronic radio-frequency (RF) signal. In the experiment, the strain applied onto the sensing FBG has been demodulated by measuring the intensity of the recovered RF signal, and by modulating the RF signal with different frequencies, different interrogation sensitivities can be achieved.

  • 144. Fu, Hongyan
    et al.
    Zhu, K.
    Ou, H. Y.
    He, Sailing
    A tunable single-passband microwave photonic filter with positive and negative taps using a fiber Mach-Zehnder interferometer and phase modulation2010Ingår i: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 42, nr 1, s. 81-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a tunable single-passband microwave photonic filter with positive and negative taps based on phase modulation and a fiber Mach-Zehnder interferometer (FMZI)) is presented, theoretically analyzed and experimentally demonstrated. The FMZI as the slicing filter results in a single-bandpass characteristic for the presented filter, and by using phase modulation, a number of negative taps are generated, thus making the baseband resonance suppressed, which is desirable for microwave photonic filter's application. The wavelength spacing of the FMZI can be tuned by employing an optical variable delay line, making the present filter continuously tunable. A tunable single-passband microwave photonic filter without baseband resonance is achieved in the experiment. The present filter shows an extinction ratio of up to similar to 20dB and good tuning linearity.

  • 145. Fu, J.
    et al.
    He, Sailing
    Analysis of higher order channel dropping tunneling processes in photonic crystals2000Ingår i: Chinese Physics Letters, ISSN 0256-307X, E-ISSN 1741-3540, Vol. 17, nr 10, s. 737-739Artikel i tidskrift (Refereegranskat)
  • 146. Fu, J.
    et al.
    He, Sailing
    KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    Xiao, S. S.
    Analysis of channel-dropping tunnelling processes in photonic crystals with multiple vertical multi-mode cavities2000Ingår i: Journal of Physics A: Mathematical and General, ISSN 0305-4470, E-ISSN 1361-6447, Vol. 33, nr 43, s. 7761-7771Artikel i tidskrift (Refereegranskat)
  • 147. Fu, J.
    et al.
    He, Sailing
    KTH, Tidigare Institutioner                               , Teoretisk elektroteknik.
    Xiao, S. S.
    Qiu, M.
    He, J. J.
    Theoretical analysis of a vertical channel dropping tunnelling process in a photonic crystal for wavelength division demultiplexing2001Ingår i: Chinese Physics Letters, ISSN 0256-307X, E-ISSN 1741-3540, Vol. 18, nr 12, s. 1613-1616Artikel i tidskrift (Refereegranskat)
  • 148. Fu, J. J.
    et al.
    Liu, W. S.
    Chen, D.
    He, Sailing
    Ultra-long-distance FBG sensor system based on spectrum-limited Fourier domain modelocking fibre laser with Raman pumps2008Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 44, nr 16, s. 961-963Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel ultra-long-distance (up to 76 km) fibre Bragg grating (FBG) sensor system based on a spectrum-limited Fourier domain modelocking fibre laser is proposed. Raman pumps are employed to form a Raman amplifier to compensate the transmission loss of the long fibre and ensure ultra-long-distance sensing. Strain sensing based on such an ultra-long-distance FBG sensor system is demonstrated with a signal-to-noise ratio over 22 dB and a sensitivity of 1.03 pm/mu epsilon in the wavelength domain or 18.3 ns/mu epsilon in the time domain.

  • 149. Fu, T.
    et al.
    Qin, Hai Yan
    KTH, Skolan för bioteknologi (BIO). KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Hu, H. J.
    Hong, Z.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Aqueous Synthesis and Fluorescence-Imaging Application of CdTe/ZnSe Core/Shell Quantum Dots with High Stability and Low Cytotoxicity2010Ingår i: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 10, nr 3, s. 1741-1746Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    CdTe/ZnSe core/shell quantum dots were directly synthesized in an aqueous condition by heating a mixed solution of ZnCl2, NaHSe and CdTe QDs in the presence of mercaptosuccinic acid as a stabilizer. By controlling the size and composition, the CdTe/ZnSe QDs with emission wavelength ranging from 540 to 630 nm, high quantum yield (44%) and narrow full width at half maximum (FWHM) could be obtained. Characterization results with HRTEM, XRD and EDX have shown that the synthesized CdTe/ZnSe ON have good monodispersity and a nice crystal structure, and exhibited better stability and less cytotoxicity as compared with CdTe QDs. Furthermore, luminescent QD-IgG bioprobes were produced to detect the breast cancer marker Her2 on the surface of fixed MCF-7 cancer cells for their optical imaging.

  • 150. Gao, S.
    et al.
    Gao, Y.
    He, Sailing
    Photonic generation of tunable multi-frequency microwave source2010Ingår i: Electronics Letters, ISSN 0013-5194, E-ISSN 1350-911X, Vol. 46, nr 3, s. 236-237Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A flexibly tunable multi-frequency microwave source is presented based on optical heterodyning between the intensity-modulated optical carrier (incorporated four-wave mixing equalisation and stabilisation) and the frequency-shifted Stokes light generated by fibre stimulated Brillouin scattering. About 20 microwave frequencies centred at 10.77 or 21.62 GHz are experimentally observed. The central frequency and the frequency spacing of the multi-frequency microwave source can be freely tuned by changing the frequency shift of the beating optical waves and the driving frequency on the modulator.

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