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Sun, F., Guo, S., Liu, Y. & He, S. (2018). A Magnifying Glass for Virtual Imaging of Subwavelength Resolution by Transformation Optics. Advanced Materials, 30(30), Article ID 1801641.
Open this publication in new window or tab >>A Magnifying Glass for Virtual Imaging of Subwavelength Resolution by Transformation Optics
2018 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 30, no 30, article id 1801641Article in journal (Refereed) Published
Abstract [en]

Traditional magnifying glasses can give magnified virtual images with diffraction-limited resolution, that is, detailed information is lost. Here, a novel magnifying glass by transformation optics, referred to as a "superresolution magnifying glass" (SMG) is designed, which can produce magnified virtual images with a predetermined magnification factor and resolve subwavelength details (i.e., light sources with subwavelength distances can be resolved). Based on theoretical calculations and reductions, a metallic plate structure to produce the reduced SMG in microwave frequencies, which gives good performance verified by both numerical simulations and experimental results, is proposed and realized. The function of SMG is to create a superresolution virtual image, unlike traditional superresolution imaging devices that create real images. The proposed SMG will create a new branch of superresolution imaging technology.

National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-232881 (URN)10.1002/adma.201801641 (DOI)000439737700023 ()29904951 (PubMedID)2-s2.0-85050392005 (Scopus ID)
Note

QC 20180809

Available from: 2018-08-09 Created: 2018-08-09 Last updated: 2018-08-09Bibliographically approved
Sun, X., Zebibula, A., Dong, X., Zhang, G., Zhang, D., Qian, J. & He, S. (2018). Aggregation-Induced Emission Nanoparticles Encapsulated with PEGylated Nano Graphene Oxide and Their Applications in Two-Photon Fluorescence Bioimaging and Photodynamic Therapy in Vitro and in Vivo. ACS Applied Materials and Interfaces, 10(30), 25037-25046
Open this publication in new window or tab >>Aggregation-Induced Emission Nanoparticles Encapsulated with PEGylated Nano Graphene Oxide and Their Applications in Two-Photon Fluorescence Bioimaging and Photodynamic Therapy in Vitro and in Vivo
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2018 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 30, p. 25037-25046Article in journal (Refereed) Published
Abstract [en]

Aggregation-induced emission (AIE) nanoparticles have been shown promise for fluorescence bioimaging and photodynamic therapy due to the good combination of nanoparticles and organic dyes or photosensitizers. Among several kinds of AIE nanoparticles, those that are capsulated with nanographene oxides (NGO) are easy to make, size-tunable, and have proven to be very stable in deionized water. However, the stability in saline solution still needs improvement for further applications in chemical or biomedical fields, and the efficacy of photodynamic therapy using NGO-capsulate AIE photosensitizers has not been evaluated yet. Herein, we modified NGO with polyethylene glycol (PEG) to improve the stability of NGO-capsulated AIE nanoparticles in phosphate buffer saline. Furthermore, by combining this modification method with a dual-functional molecule which has both typical AIE property and photosensitizing ability, we performed both two-photon fluorescence bioimaging and photodynamic therapy in vitro and in vivo. Our work shows that AIE nanoparticles capsulated with PEGylated nanographene oxide can be a powerful tool for future bioimaging and photodynamic therapy applications.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
aggregation-induced emission, nanographene oxide, nanoparticles, bioimaging, photodynamic therapy, tumor
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-233418 (URN)10.1021/acsami.8b05546 (DOI)000440956000012 ()29979575 (PubMedID)2-s2.0-85049683523 (Scopus ID)
Note

QC 20180821

Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved
Liu, Y., Sun, F. & He, S. (2018). Controlling lightwave in Riemann space by merging geometrical optics with transformation optics. Scientific Reports, 8(1), Article ID 514.
Open this publication in new window or tab >>Controlling lightwave in Riemann space by merging geometrical optics with transformation optics
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 514Article in journal (Refereed) Published
Abstract [en]

In geometrical optical design, we only need to choose a suitable combination of lenses, prims, and mirrors to design an optical path. It is a simple and classic method for engineers. However, people cannot design fantastical optical devices such as invisibility cloaks, optical wormholes, etc. by geometrical optics. Transformation optics has paved the way for these complicated designs. However, controlling the propagation of light by transformation optics is not a direct design process like geometrical optics. In this study, a novel mixed method for optical design is proposed which has both the simplicity of classic geometrical optics and the flexibility of transformation optics. This mixed method overcomes the limitations of classic optical design; at the same time, it gives intuitive guidance for optical design by transformation optics. Three novel optical devices with fantastic functions have been designed using this mixed method, including asymmetrical transmissions, bidirectional focusing, and bidirectional cloaking. These optical devices cannot be implemented by classic optics alone and are also too complicated to be designed by pure transformation optics. Numerical simulations based on both the ray tracing method and full-wave simulation method are carried out to verify the performance of these three optical devices.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-221681 (URN)10.1038/s41598-017-19015-0 (DOI)000419941400001 ()2-s2.0-85040445799 (Scopus ID)
Funder
Swedish Research Council, 2012AA030402
Note

QC 20180122

Available from: 2018-01-22 Created: 2018-01-22 Last updated: 2018-01-29Bibliographically approved
Gong, Y., Yang, B., Zhang, D., Hong, X., Lu, Y., He, S. & Chen, J. (2018). Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks. Optics Communications, 426, 151-157
Open this publication in new window or tab >>Crosstalk-aware multiple-AWG based optical interconnects for datacenter networks
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2018 (English)In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 426, p. 151-157Article in journal (Refereed) Published
Abstract [en]

This paper proposes a crosstalk-aware passive optical interconnect architecture based on multiple arrayed waveguide gratings (AWGs). With two-stage cascaded AWGs, it can realize the communications not only within but also among the clusters for large-scale datacenters. To overcome serious crosstalk in multiple-AWG based optical interconnects, crosstalk suppression schemes are proposed. Proof-of-concept experiments are carried out to verify the necessity and feasibility of the proposed crosstalk suppression schemes for multiple-AWG based optical interconnects.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Crosstalk-aware interconnect, Data center network, Passive optical interconnect
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-229277 (URN)10.1016/j.optcom.2018.05.022 (DOI)000437381300025 ()2-s2.0-85047348276 (Scopus ID)
Funder
Swedish Foundation for Strategic Research Swedish Research Council
Note

QC 20180601

Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-07-27Bibliographically approved
Shi, K., Liao, R., Cao, G., Bao, F. & He, S. (2018). Enhancing thermal radiation by graphene-assisted hBN/SiO2 hybrid structures at the nanoscale. Optics Express, 26(10), A591-A601
Open this publication in new window or tab >>Enhancing thermal radiation by graphene-assisted hBN/SiO2 hybrid structures at the nanoscale
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2018 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 26, no 10, p. A591-A601Article in journal (Refereed) Published
Abstract [en]

A graphene-assisted hBN/SiO2, hybrid structure is proposed and demonstrated to enhance near-field thermal radiation (NFTR). Due to the complementarity between the hyperbolic phonon polaritons of hBN and the surface phonon polaritons of SiO2, at mid-infrared frequencies, coupling modes can remarkably improve the photon tunneling probability over a broad frequency band, especially when assisted by the surface plasmon polaritons of graphene sheets. Thus, the heat flux can exceed the blackbody limit by 4 orders of magnitude at a separation distance of 10 nm and reach 97% of the infinite limit of graphene-hBN multilayers using only two layers with a thickness of 20 nm each. The first graphene layer controls most of the heat flux, while the other layers can be used to regulate and optimize. The dynamic relationship between the chemical potential mu and the gap distance d are thoroughly discussed. Optimal heat flux of our graphene-assisted hBN/SiO2 hybrid structure with proper choices of (mu(1), mu(2), mu(3)) for different d (from 10 nm to 1000 nm) is further increased by 28.2% on average in comparison with the existing graphene-hBN triple-layer structure.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2018
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-231224 (URN)10.1364/OE.26.00A591 (DOI)000432457600017 ()29801276 (PubMedID)2-s2.0-85047334238 (Scopus ID)
Note

QC 20180628

Available from: 2018-06-28 Created: 2018-06-28 Last updated: 2018-06-28Bibliographically approved
Li, J., Jiang, W., Yao, X., Cai, F. & He, S. (2018). Fast quantitative fluorescence authentication of milk powder and vanillin by a line-scan hyperspectral system. Applied Optics, 57(22), 6276-6282
Open this publication in new window or tab >>Fast quantitative fluorescence authentication of milk powder and vanillin by a line-scan hyperspectral system
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2018 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 57, no 22, p. 6276-6282Article in journal (Refereed) Published
Abstract [en]

We present a fast hyperspectral line-scan fluorescence imaging system to verify the feasibility of quantitative fluorescence authentication of powders. Vanillin, which is restricted for use in milk powder, especially in milk powder for infants, is mixed with milk powder in different mass concentrations (5%, 10%, 30%, 50%, 70%, and 90%). Mixed powders are located on a motorized linear stage. A 405 nm line laser is utilized to excite the fluorescence of the sample. Based on galvo scanning, we can generate a laser line with high spatial resolution and high-intensity density on the samples. An imaging spectrometer with a complementary metal-oxide semiconductor (CMOS) camera as detector is built. The spectral range of the spectrometer is 365-810 nm, with about 1 nm spectral resolution. One snapshot of the CMOS can acquire the fluorescent spatial and spectral information of a line region in 100 ms. By scanning the motorized linear stage, we obtain the fluorescence hypercube of the sample. A 100 x 1926 x 1216 hypercube, which covers an area of 15 mm x 5 mm, is obtained in 50 s. The imaging speed can be enhanced further by increasing the intensity of the excitation laser and the sensitivity of the area camera. Fully constrained least squares, a linear spectral mixture analysis, is utilized to analyze the hypercube obtained by our homemade imaging spectrometer, thus obtaining the pixel concentration of vanillin in each mixed powder. Linear regression analysis is used for the pixel concentration and mass concentration of vanillin. A linear relationship with coefficient of determination le equal to one is observed, which demonstrates the capability of fluorescence hyperspectral quantitative analysis in powders.

Place, publisher, year, edition, pages
Optical Society of America, 2018
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-233285 (URN)10.1364/AO.57.006276 (DOI)000440439900031 ()2-s2.0-85051253294 (Scopus ID)
Note

QC 20180821

Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved
Man, S., Gee, Y., Jun, Y., Yungui, M. & He, S. (2018). FeGaB(25 nm)/Al2O3/FeGaB(25 nm) Multilayer Structures: Effects of Variation of Al(2)O(3)Thickness on Static and Dynamic Magnetic Properties. Xiyou jinshu cailiao yu gongcheng, 47(7), 1951-1957
Open this publication in new window or tab >>FeGaB(25 nm)/Al2O3/FeGaB(25 nm) Multilayer Structures: Effects of Variation of Al(2)O(3)Thickness on Static and Dynamic Magnetic Properties
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2018 (English)In: Xiyou jinshu cailiao yu gongcheng, ISSN 1002-185X, Vol. 47, no 7, p. 1951-1957Article in journal (Refereed) Published
Abstract [en]

Iron-gallium (FeGa) thin film has the unique advantages in designing integrated magnetic sensors or chips due to its relatively large magnetostrictive constant compared with other soft magnetic materials. In this work, non-magnetic doping and laminating methods have been employed to control the magnetic and electric properties of this alloy film. By doping a certain amount of boron (B), the coercivities are largely decreased for samples of thickness less than similar to 30 nm. For thicker films, we find that inserting an ultrathin Al2O3 middle layer is very helpful to control the coercivities with negligible influence on saturation magnetization (M-s). The smallest easy-axis coercivity of 0.98x79.6 A/m is obtained in the multilayer film FeGaB(25 nm)/Al2O3(0.5 nm)/FeGaB(25 nm). In this case, the resistivity is enhanced by 1.5 times compared with the 50 nm single layer film. Structural characterizations indicate the reductions of crystalline quality and physical dimension of the magnetic grains playing important roles in softening the magnetic properties. Besides, the influences of magnetostatic interaction and morphology characteristics are also considered in facilitating domain reversal. High permeability spectra with gigahertz response are obtained for our multilayer films. The methodology applied here, i.e., enhancing magnetic and electric performance by introducing ultrathin non-magnetic layers, could be translated to other species of soft magnetic materials as well.

Place, publisher, year, edition, pages
NORTHWEST INST NONFERROUS METAL RESEARCH, 2018
Keywords
iron-gallium boron, multilayer structure, aluminum oxide, soft magnetic property
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-233611 (URN)000441099900001 ()
Note

QC 20180827

Available from: 2018-08-27 Created: 2018-08-27 Last updated: 2018-08-27Bibliographically approved
Liu, W., Wang, Y., Han, X., Lu, P., Zhu, L., Sun, C., . . . He, S. (2018). Fluorescence resonance energy transfer (FRET) based nanoparticles composed of AIE luminogens and NIR dyes with enhanced three-photon near-infrared emission for in vivo brain angiography. Nanoscale, 10(21), 10025-10032
Open this publication in new window or tab >>Fluorescence resonance energy transfer (FRET) based nanoparticles composed of AIE luminogens and NIR dyes with enhanced three-photon near-infrared emission for in vivo brain angiography
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2018 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 10, no 21, p. 10025-10032Article in journal (Refereed) Published
Abstract [en]

Near-infrared (NIR) fluorescence is very important for high-contrast biological imaging of high-scattering tissues such as brain tissue. Unfortunately, commercial NIR dyes are excited usually by visible light, and their multi-photon absorption (MPA) cross-sections are small. Here, we design new co-encapsulated NIR nanoparticles (NPs) with a large three-photon (3PA) absorption cross-section. A form of aggregation-induced emission (AIE) luminogen (AIEgen), 2,3-bis(4-(diphenylamino)-[1,1-biphenyl]-4-yl) fumaronitrile (TPATCN), is introduced as the donor, and a form of NIR dye, silicon 2,3-naphthalocyanine bis-(trihexylsilyloxide) (NIR775), is adopted as the acceptor. Under the excitation of a 1550 nm fs laser, TPATCN-NIR775 NPs demonstrated a bright three-photon fluorescence centered at 785 nm. The energy transfer efficiency of the TPATCN-NIR775 NPs was calculated to be as high as 90%, which could be attributed to the good spectral overlap between the emission of TPATCN and the absorption of NIR775. By injection with TPATCN-NIR775 NPs, a vivid 3D reconstruction of mouse brain vasculature was obtained with even small blood vessels clearly visualized. The design strategy used for the co-encapsulated AIE-NIR NPs would be helpful in synthesizing more NIR probes for deep-tissue biological imaging in the future.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-231189 (URN)10.1039/c8nr00066b (DOI)000434313200024 ()29774924 (PubMedID)2-s2.0-85047923955 (Scopus ID)
Note

QC 20180720

Available from: 2018-07-20 Created: 2018-07-20 Last updated: 2018-07-20Bibliographically approved
Zheng, J., Xing, X., Yang, J., Shi, K. & He, S. (2018). Hybrid optofluidics and three-dimensional manipulation based on hybrid photothermal waveguides. NPG Asia Materials, 10
Open this publication in new window or tab >>Hybrid optofluidics and three-dimensional manipulation based on hybrid photothermal waveguides
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2018 (English)In: NPG Asia Materials, ISSN 1884-4049, Vol. 10Article in journal (Refereed) Published
Abstract [en]

Despite enormous breakthroughs in lab-on-a-chip techniques, light-driven manipulation faces two long-standing challenges: the ability to achieve both multiform manipulation and tunable manipulation range and the means to avoid potential thermal damage to the targets. By harnessing the optical heating of hybrid photothermal waveguides (HPW), we develop a hybrid optofluidic technique involving buoyancy and thermocapillary convection to achieve fluid transport with controllable modes and tunable strength. Switching of the optofluidic mode from buoyancy to thermocapillary convection, namely, from vertical to horizontal vortices, is employed for three-dimensional manipulation. The strong confinement and torque in the vortices are capable of trapping and rotating/spinning particles at the vortex centers rather than the HPW. Buoyancy convection provides a trapping circle to achieve collective trapping and vertical rotation/spin, while thermocapillary convection offers a trapping lattice to achieve distributed trapping and horizontal rotation/spin. By integrating micro/nanoparticles with various properties and sizes, further investigations of the optofluidic arrangement, mixing, and synthesis will broaden the potential applications of the hybrid optofluidic technique in the fields of lab-on-a-chip, materials science, chemical synthesis and analysis, photonics, and nanoscience.

Place, publisher, year, edition, pages
Nature Publishing Group, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-232796 (URN)10.1038/s41427-018-0026-5 (DOI)000438883900001 ()2-s2.0-85045736834 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20180802

Available from: 2018-08-02 Created: 2018-08-02 Last updated: 2018-08-02Bibliographically approved
Hong, Y., Hong, X., He, S. & Chen, J. (2018). Hybrid Routing and Adaptive Spectrum Allocation for Flex-Grid Optical Interconnects. Journal of Optical Communications and Networking, 10(5), 506-514
Open this publication in new window or tab >>Hybrid Routing and Adaptive Spectrum Allocation for Flex-Grid Optical Interconnects
2018 (English)In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 10, no 5, p. 506-514Article in journal (Refereed) Published
Abstract [en]

A hybrid routing scheme with an adaptive spectrum assignment is proposed for flex-grid all-optical core switch supporting multihop transparent paths in data center networks. Compared with conventional spectrum assignment algorithms (RSA) developed for a multihop network with optical-electric-optical (OEO) conversion in every hop (i.e., RSA for EO) and that devised for an all-optical multihop network (i.e., RSA for AO), the present RSA algorithm provides better utilization of network resources. Being aware of the all-optical bypass path in hopping, the proposed RSA reduces the blocking probability due to lack of bandwidth-tunable transceivers, which is the major reason for blocking for an RSA for the EO. Similar to the RSA for the AO, the proposed RSA is compatible with the number-of-hops adaptive spectrum assignment, which improves spectrum efficiency. On the other hand, the new algorithm enhances connectivity by eliminating the number-of-hops limitation, which severely constrains the performance of RSA for the AO. Simulations for the system are carried out to investigate the performance of the new algorithm. The impacts of various parameters, such as traffic load, ratio of connection requests with different data rates, and resource configuration on the link cost, are studied in terms of network blocking probability (BP). The achievable traffic load of the proposed RSA under varied connection degrees (i.e., the maximum number of ports that one rack has in order to connect to the core switch) and number of racks is also assessed to keep BP no more than 0.1. The results show that the proposed RSA with appropriate cost functions outperforms the EO and AO, which implies that it has the highest scalability.

Place, publisher, year, edition, pages
Optical Society of America, 2018
Keywords
Data center network, Optical circuit switching, Optical interconnect, Routing and spectrum assignment (RSA)
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-229027 (URN)10.1364/JOCN.10.000506 (DOI)000432318600006 ()2-s2.0-85047218710 (Scopus ID)
Funder
Swedish Foundation for Strategic Research Swedish Research Council
Note

QC 20180531

Available from: 2018-05-31 Created: 2018-05-31 Last updated: 2018-05-31Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3401-1125

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