Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 589) Show all publications
Tan, C., Su, X., Zhou, C., Wang, B., Zhan, Q. & He, S. (2017). Acid-assisted hydrothermal synthesis of red fluorescent carbon dots for sensitive detection of Fe(III). RSC Advances, 7(65), 40952-40956.
Open this publication in new window or tab >>Acid-assisted hydrothermal synthesis of red fluorescent carbon dots for sensitive detection of Fe(III)
Show others...
2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 65, 40952-40956 p.Article in journal (Refereed) Published
Abstract [en]

Red-emitting carbon dots (C-dots) were synthesized from p-phenylenediamine (p-PD) aqueous solution with nitric acid (HNO3) assistance by hydrothermal reaction at 200 degrees C for 2 h. p-PD aqueous solution can be transferred to C-dots (or poly(p-PD)) with (or without) the addition of acid. Different acid systems, such as HNO3, H3PO4 and HF, can directly synthesize red-emitting C-dots, and the fluorescence can be enhanced by increasing the strength of acids. N-CDs, 3.46 nm-average-sized C-dots, prepared in dilute HNO3, have a quantum yield of 15.8% with unique, excitation-wavelength independent emission in the red region (600 and 680 nm) and a broad visible excitation band. Carboxyl, ester and hydroxyl groups on the C-dots surface directly lead to red emission. N-CDs have a certain selective specificity for Fe3+ detection and the linear range is 10-300 nmol L-1 with a limit of determination of 1.9 nmol L-1.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2017
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-214912 (URN)10.1039/c7ra06223k (DOI)000409096300033 ()2-s2.0-85028360093 (Scopus ID)
Note

QC 2016-09-27

Available from: 2017-09-27 Created: 2017-09-27 Last updated: 2017-11-29Bibliographically approved
Li, B., Sun, F. & He, S. (2017). Acoustic surface transformation realized by acoustic-null materials using bilayer natural materials. APPLIED PHYSICS EXPRESS, 10(11), Article ID 114001.
Open this publication in new window or tab >>Acoustic surface transformation realized by acoustic-null materials using bilayer natural materials
2017 (English)In: APPLIED PHYSICS EXPRESS, ISSN 1882-0778, Vol. 10, no 11, 114001Article in journal (Refereed) Published
Abstract [en]

We propose a general method, known as acoustic surface transformation (AST), to design novel acoustic devices and study the realization of such devices by using naturally available materials in broadband acoustic frequencies. All devices designed by AST only need one anisotropic homogeneous acoustic-null material (ANM). We design the ANM by exploiting natural material-based metal-fluid structures and verify that by numerical simulation. Unlike traditional methods, no complicated mathematical calculations are needed. We only need to design the geometrical shapes of the input and output surfaces of the devices. The proposed method will pave a new road for future acoustic design.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-217421 (URN)10.7567/APEX.10.114001 (DOI)000413839000001 ()
Note

QC 20171117

Available from: 2017-11-17 Created: 2017-11-17 Last updated: 2017-11-17Bibliographically approved
Yang, L., Kou, P., He, N., Dai, H. & He, S. (2017). Anomalous light trapping enhancement in a two-dimensional gold nanobowl array with an amorphous silicon coating. Optics Express, 25(13), 14114-14124.
Open this publication in new window or tab >>Anomalous light trapping enhancement in a two-dimensional gold nanobowl array with an amorphous silicon coating
Show others...
2017 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 13, 14114-14124 p.Article in journal (Refereed) Published
Abstract [en]

A facile polymethyl methacrylate-assisted turnover-transfer approach is developed to fabricate uniform hexagonal gold nanobowl arrays. The bare array shows inferior light trapping ability compared to its inverted counterpart (a gold nanospherical shell array). Surprisingly, after being coated with a 60-nm thick amorphous silicon film, an anomalous light trapping enhancement is observed with a significantly enhanced average absorption (82%), while for the inverted nanostructure, the light trapping becomes greatly weakened with an average absorption of only 66%. Systematic experimental and theoretical results show that the main reason for the opposite light trapping behaviors lies in the top amorphous silicon coating, which plays an important role in mediating the excitation of surface plasmon polaritons and the electric field distributions in both nanostructures.

Place, publisher, year, edition, pages
Optical Society of America, 2017
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-211008 (URN)000404189800016 ()2-s2.0-85021327644 (Scopus ID)
Note

QC 20170713

Available from: 2017-07-13 Created: 2017-07-13 Last updated: 2017-11-29Bibliographically approved
Zhao, K., Gustafson, C., Liao, Q., Zhang, S., Bolin, T., Ying, Z. & He, S. (2017). Channel Characteristics and User Body Effects in an Outdoor Urban Scenario at 15 and 28 GHz. IEEE Transactions on Antennas and Propagation, 65(12), 6534-6548.
Open this publication in new window or tab >>Channel Characteristics and User Body Effects in an Outdoor Urban Scenario at 15 and 28 GHz
Show others...
2017 (English)In: IEEE Transactions on Antennas and Propagation, ISSN 0018-926X, E-ISSN 1558-2221, Vol. 65, no 12, 6534-6548 p.Article in journal (Refereed) Published
Abstract [en]

The effect of a user's body on channel characteristics for single user downlink transmission in an urban scenario for the fifth generation (5G) systems is investigated with ray-tracing at 15 and 28 GHz. Three different designs of user equipment (UE) antennas are fabricated and integrated into a mobile phone prototype, and their 3-D radiation patterns are measured both with and without a user. The user remains in Cellular Telephone Industries Association (CTIA) standard data mode and talk mode during measurements. The results show that the user's body will cause a strong shadowing loss and generate a large fluctuation on the received signal strength of the UE at both 15 and 28 GHz, which is crucial to channel modeling studies at frequencies above 6 GHz. In addition, the user's body effect on a linear array system in an UE is presented, and the main challenges for the future work are also addressed.

Place, publisher, year, edition, pages
IEEE, 2017
Keyword
5G, array, body effect, channel, millimeter wave (mmWave), mobile phone, user equipment (UE)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-215256 (URN)10.1109/TAP.2017.2740959 (DOI)000417885000031 ()2-s2.0-85028501647 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4620
Note

QC 20171005

Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2018-01-12Bibliographically approved
Jiang, W., Ma, Y., Yuan, J., Yin, G., Wu, W. & He, S. (2017). Deformable broadband metamaterial absorbers engineered with an analytical spatial Kramers-Kronig permittivity profile. Laser & Photonics reviews, 11(1), Article ID 1600253.
Open this publication in new window or tab >>Deformable broadband metamaterial absorbers engineered with an analytical spatial Kramers-Kronig permittivity profile
Show others...
2017 (English)In: Laser & Photonics reviews, ISSN 1863-8880, E-ISSN 1863-8899, Vol. 11, no 1, 1600253Article in journal (Refereed) Published
Abstract [en]

Electromagnetic (EM) materials with perfect absorption have long been investigated for their important applications in many practical technologies. The trial-and-error method has been mostly employed to achieve this target, either by varying the constituent compositions for traditional natural material absorbers or by running computer simulations for general metamaterial (MM) absorbers. In this work, the authors propose a new method with analytical guidance to build omnidirectional perfect absorbers inspired by the recently proposed spatial Kramers-Kronig (KK) nonreflecting dielectric profile. The subtle combination of the spatial and time dispersions in the metamaterial-engineered KK profile gives the desired broadband response property. More importantly, these features remain invariant when the sample is uniformly compressed or stretched with large thickness change, i.e., this particular broadband absorber is deformable, which has been firstly reported in the literature. The current results will pave a new way to design high-efficiency EM absorbers that could also be extended in general to manipulate waves for other fields or applications. (Figure presented.).

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keyword
absorber, dispersion engineering, metamaterial, Deformation, Dispersion (waves), Dispersions, Broadband absorbers, Broadband response, Dielectric profiles, Metamaterial absorbers, Permittivity profiles, Trial-and-error method, Metamaterials
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-202266 (URN)10.1002/lpor.201600253 (DOI)000393316000010 ()2-s2.0-85006990457 (Scopus ID)
Note

Funding text: The authors are grateful to the partial supports from NSFC (61271085 and 91233208), NSF of Zhejiang province (LR15F050001), the Program of Zhejiang Leading Team of Science and Technology Innovation (2010R50007), Swedish VR and AOARD. QC 20170221

Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2017-11-29Bibliographically approved
Hong, Y., Hong, X., Chen, J. & He, S. (2017). Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation. Optics Communications, 383, 478-484.
Open this publication in new window or tab >>Elastic all-optical multi-hop interconnection in data centers with adaptive spectrum allocation
2017 (English)In: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 383, 478-484 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, a novel flex-grid all-optical interconnect scheme that supports transparent multi-hop connections in data centers is proposed. An inter-rack all-optical multi-hop connection is realized with an optical loop employed at flex-grid wavelength selective switches (WSSs) in an intermediate rack rather than by relaying through optical-electric-optical (O-E-O) conversions. Compared with the conventional O-E-O based approach, the proposed all-optical scheme is able to off-load the traffic at intermediate racks, leading to a reduction of the power consumption and cost. The transmission performance of the proposed flex-grid multi-hop all-optical interconnect scheme with various modulation formats, including both coherently detected and directly detected approaches, are investigated by Monte-Carlo simulations. To enhance the spectrum efficiency (SE), number-of-hop adaptive bandwidth allocation is introduced. Numerical results show that the SE can be improved by up to 33.3% at 40 Gbps, and by up to 25% at 100 Gbps. The impact of parameters, such as targeted bit error rate (BER) level and insertion loss of components, on the transmission performance of the proposed approach are also explored. The results show that the maximum SE improvement of the adaptive approach over the non-adaptive one is enhanced with the decrease of the targeted BER levels and the component insertion loss.

Place, publisher, year, edition, pages
Elsevier, 2017
Keyword
Data center network, Flex-grid, Multi-hop, Optical circuit switching, Optical interconnect, Bit error rate, Electric switches, Insertion losses, Intelligent systems, Monte Carlo methods, Optical interconnects, Optical switches, Plasma diagnostics, Data center networks, Multihop, Adaptive optics
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-195118 (URN)10.1016/j.optcom.2016.09.027 (DOI)000386870700073 ()2-s2.0-84988970672 (Scopus ID)
Note

Funding Details: VR, Swedish Research Council. QC 20161121

Available from: 2016-11-21 Created: 2016-11-02 Last updated: 2017-11-29Bibliographically approved
Shi, K., Bao, F. & He, S. (2017). Enhanced Near-Field Thermal Radiation Based on Multilayer Graphene-hBN Heterostructures. ACS PHOTONICS, 4(4), 971-978.
Open this publication in new window or tab >>Enhanced Near-Field Thermal Radiation Based on Multilayer Graphene-hBN Heterostructures
2017 (English)In: ACS PHOTONICS, ISSN 2330-4022, Vol. 4, no 4, 971-978 p.Article in journal (Refereed) Published
Abstract [en]

Graphene-covered hexagonal boron nitride (hBN) can exceed blackbody thermal radiation in near-field due to the coupling of surface plasmon polaritons (SPPs) and hyperbolic phonon polaritons (HPPs). As previous research found that the thickness of hBN in a graphene-hBN cell can be very thin while still presenting strong radiation enhancement, multilayer graphene-hBN heterostructures are proposed in this paper to further enhance the near-field thermal radiation. We found that a heterostructure consisting of five or more graphene-hBN cells performs better than all existing graphene-hBN configurations, and the infinite cell limit exhibits 1.87- and 2.94-fold larger heat flux at 10 nm separation than sandwich and monocell structures do, respectively, due to the continuously and perfectly coupled modes. The heat flux is found to be 4 orders of magnitude larger than that of the blackbody. The effective tunability of the thermal radiation of the multicell structure is also observed by adjusting the chemical potentials of graphene with an optimized thickness of 20 nm on each hBN, which is instructive for both experimental design and fabrication of thermal radiation devices.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
Keyword
near-field, thermal radiation, graphene-hBN heterostructure
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-207696 (URN)10.1021/acsphotonics.7b00037 (DOI)000399968500037 ()2-s2.0-85018496767 (Scopus ID)
Note

QC 20170531

Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
Gong, C., Zhang, J. & He, S. (2017). Hybrid unidirectional meta-coupler for vertical incidence to a high-refractive-index waveguide in telecom wavelength. Optics Letters, 42(24), 5098-5101.
Open this publication in new window or tab >>Hybrid unidirectional meta-coupler for vertical incidence to a high-refractive-index waveguide in telecom wavelength
2017 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 42, no 24, 5098-5101 p.Article in journal (Refereed) Published
Abstract [en]

Unidirectional optical manipulation, especially the coupling from a vertical light beam to a waveguide unidirectionally, is desirable in photonic integration. We first propose a hybrid unidirectional meta-coupler for vertical incidence to a high-refractive-index waveguide in telecom wavelength, a periodic plasmonic metasurface composed of metal-insulator-metal unit cells is used for phase matching. Three designs are given for devices working around wavelengths 0.85, 1.31, and 1.55 mu m. The simulated coupling efficiencies are all around 70%, and the 1 dB coupling bandwidths are 29, 82, and 105 nm, respectively. Our approach paves the way for the applications of optical metasurfaces to planar lightwave circuits. (C) 2017 Optical Society of America

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2017
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-220829 (URN)10.1364/OL.42.005098 (DOI)000418019100012 ()29240146 (PubMedID)2-s2.0-85038216950 (Scopus ID)
Note

QC 20170111

Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-01-11Bibliographically approved
Kou, P., Yang, L., Chang, C. & He, S. (2017). Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach. Scientific Reports, 7, Article ID 42052.
Open this publication in new window or tab >>Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 42052Article in journal (Refereed) Published
Abstract [en]

Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm(2), 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Omega/sq and transmittance of similar to 87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-202773 (URN)10.1038/srep42052 (DOI)000393512000001 ()28169343 (PubMedID)
Note

QC 20170307

Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2017-11-29Bibliographically approved
Kou, P., Yang, L., Chang, C. & He, S. (2017). Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach. Scientific Reports, 7, Article ID 42052.
Open this publication in new window or tab >>Improved Flexible Transparent Conductive Electrodes based on Silver Nanowire Networks by a Simple Sunlight Illumination Approach
2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 42052Article in journal (Refereed) Published
Abstract [en]

Silver nanowire (Ag NW) networks have attracted wide attention as transparent electrodes for emerging flexible optoelectronics. However, the sheet resistance is greatly limited by large wire-to-wire contact resistances. Here, we propose a simple sunlight illumination approach to remarkably improve their electrical conductivity without any significant degradation of the light transmittance. Because the power density is extremely low (0.1 W/cm(2), 1-Sun), only slight welding between Ag NWs has been observed. Despite this, a sheet resistance of <20 Omega/sq and transmittance of similar to 87% at wavelength of 550 nm as well as excellent mechanical flexibility have still been achieved for Ag NW networks after sunlight illumination for 1 hour or longer, which are significant upgrades over those of ITO. Slight plasmonic welding together with the associated self-limiting effect has been investigated by numerical simulations and further verified experimentally through varied solar concentrations. Due to the reduced resistance, high-performance transparent film heaters as well as efficient defrosters have been demonstrated, which are superior to the previously-reported Ag NW based film heaters. Since the sunlight is environmentally friendly and easily available, sophisticated or expensive facilities are not necessary. Our findings are particularly meaningful and show enormous potential for outdoor applications.

Place, publisher, year, edition, pages
Nature Publishing Group, 2017
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-202641 (URN)10.1038/srep42052 (DOI)000393512000001 ()28169343 (PubMedID)2-s2.0-85011840613 (Scopus ID)
Note

QC 20170307

Available from: 2017-03-07 Created: 2017-03-07 Last updated: 2017-11-29Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3401-1125

Search in DiVA

Show all publications