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1550 nm

Martin Mittendorff, Ryan J Suess, Edward Leong, Thomas E Murphy
Photoconductive antennas are widely used for time-resolved detection of THz pulses. In contrast to photothermoelectric or bolometric THz detection, the coherent detection allows direct measurement of the electric field transient of a THz pulse, which contains both, spectral and phase information. In this letter we demonstrate for the first time photoconductive detection of free-space propagating THz radiation with thin flakes of a van der Waals material. Mechanically exfoliated flakes of black phosphorus are combined with an antenna that concentrates the THz fields to the small flake (~10 μm)...
August 18, 2017: Nano Letters
Marina Perper, Adam S Aldahan, Rachel A Fayne, Christopher P Emerson, Keyvan Nouri
Hair loss stemming from different types of alopecia, such as androgenic alopecia and alopecia areata, negatively affects over half the population and, in many circumstances, causes serious psychosocial distress. Current treatment options for alopecia, such as minoxidil, anthralin, and intralesional corticosteroids, vary efficacy and side effect profiles. It is known that low-level laser/light therapies (LLLT), or photobiomodulations, such as the US FDA-cleared HairMax Lasercomb®, He-Ne laser, and excimer laser, are relatively affordable, user-friendly, safe, and effective forms of treatment for hair loss...
August 16, 2017: Lasers in Medical Science
Hilal Gokalp
Fractional lasers have been used for the improvement of scar tissue in the recent years but there has not been extensive research on their impact. The purpose of this study was to evaluate the efficacy of nonablative fractional laser (NAFL) on acne, burn, and surgery/traumatic scar. The scars were also categorized as atrophic, hypertrophic, and keloid, and treatment efficacy was investigated accordingly. This is a retrospective, single-center study. Scar tissues were treated using a nonablative fractional 1550-nm Erbium glass laser in high-energy parameters at 4-week interval for 4-8 sessions...
August 12, 2017: Lasers in Medical Science
Yalun Wang, Xiao Han, Wang Xi, Jinyu Li, Anna Wang Roe, Ping Lu, Jun Qian
Deep-tissue imaging is of great significance to biological applications. In this paper, a deep-red emissive luminogen 2,3-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl) fumaronitrile (TPATCN) with aggregation-induced emission (AIE) feature is prepared. TPATCN molecules were then encapsulated within a polymeric matrix of Pluronic F-127 to form nanoparticles (NPs). TPATCN NPs exhibit bright three-photon fluorescence (3PF) in deep-red region, together with high chemical stability, good photostability, and biocompatibility...
August 10, 2017: Advanced Healthcare Materials
Bar Baruch Ben Zaken, Tal Zanzury, Dror Malka
We propose a novel 8-channel wavelength multimode interference (MMI) demultiplexer in slot waveguide structures that operate at 1530 nm, 1535 nm, 1540 nm, 1545 nm, 1550 nm, 1555 nm, 1560 nm, and 1565 nm. Gallium nitride (GaN) surrounded by silicon (Si) was found to be a suitable material for the slot-waveguide structures. The proposed device was designed by seven 1 × 2 MMI couplers, fourteen S-bands, and one input taper. Numerical investigations were carried out on the geometrical parameters using a full vectorial-beam propagation method (FV-BPM)...
November 1, 2016: Materials
Guangyang Lin, Ningli Chen, Lu Zhang, Zhiwei Huang, Wei Huang, Jianyuan Wang, Jianfang Xu, Songyan Chen, Cheng Li
Direct band electroluminescence (EL) from tensile-strained Si0.13Ge0.87/Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300-1400 nm and 1600-1700 nm, respectively...
September 27, 2016: Materials
Xiao-Fang Jiang, Zhikai Zeng, Shuang Li, Zhinan Guo, Han Zhang, Fei Huang, Qing-Hua Xu
Broadband nonlinear optical properties from 500 to 1550 nm of ultrasmall black phosphorus quantum dots (BPQDs) have been extensively investigated by using the open-aperture Z-scan technique. Our results show that BPQDs exhibit significant nonlinear absorption in the visible range, but saturable absorption in the near-infrared range under femtosecond excitation. The calculated nonlinear absorption coefficients were found to be (7.49 ± 0.23) × 10(-3), (1.68 ± 0.078) × 10(-3) and (0.81 ± 0.03) × 10(-3) cm/GW for 500, 700 and 900 nm, respectively...
February 21, 2017: Materials
Yanliang He, Ying Li, Junmin Liu, Xiaoke Zhang, Yao Cai, Yu Chen, Shuqing Chen, Dianyuan Fan
Singular beams which possess helical phase wavefront or spatially inhomogeneous polarization provide new freedom for optical field manipulation. However, conventional schemes to produce the singular beams have difficulty in realizing the flexible switch between different singular beams. In this work, we have experimentally demonstrated the capability of dielectric metasurfaces to generate three types of singular beams and switch between them at working wavelength of 1550  nm. We have shown vortex beam and cylindrical vector beam generation with single metasurface and cylindrical vector vortex beam generation with two cascaded metasurfaces...
July 28, 2017: Scientific Reports
Ran Gao, Danfeng Lu, Jin Cheng, Zhi-Mei Qi
A real-time all-fiber anemometer based on laser-heated few-layer graphene in aligned graded-index fibers has been proposed and experimentally demonstrated. The proposed fiber-optic anemometer was composed of a pair of all-fiber collimators by using aligned graded-index fibers that was coated with the few-layer graphene. The few-layer graphene was heated through a heating light from a 532-nm laser, which changed the optical transmittance of signal light with the wavelength of 1550 nm. The wind speed can be measured through the transmission power of the signal light based on the wind cooling effects on the heated few-layer graphene, acting as a "hot-wire" anemometer...
July 15, 2017: Optics Letters
Ming-Sheng Lai, Chia-Chien Huang
We propose a polarization beam splitter (PBS) with a footprint of only 600 × 790 nm(2) operating at a wavelength of λ = 1550 nm, which is the smallest PBS ever demonstrated. This device uses CMOS-compatible materials, namely, silicon and silica. The present PBS comprises two Si waveguides with different geometrical aspect ratios adjoined side-by-side, which separates the transverse-electric (TE) and transverse-magnetic (TM) modes without relying on an additional coupling region. The designed PBS achieves a polarization extinction ratio of approximately 25 dB for both modes and insertion losses of approximately 0...
July 3, 2017: Scientific Reports
Hilal Gokalp
BACKGROUND: Striae distensae (SD) are a type of dermal scarring that is quite common and difficult to treat. Two forms are known: striae rubrae (SR) and striae albae (SA). OBJECTIVE: We evaluated and compared the long-term clinical effectiveness of SR and SA treatment using a 1550-nm non-ablative fractional laser (NAFL). MATERIALS AND METHODS: We included 16 female patients (8 with SR and 8 with SA) who had developed abdominal SD during pregnancy...
June 30, 2017: Journal of Cosmetic and Laser Therapy: Official Publication of the European Society for Laser Dermatology
Hongxin Zhang, Tianqing Jia, Long Chen, Yuchan Zhang, Shian Zhang, Donghai Feng, Zhenrong Sun, Jianrong Qiu
We report optical depletion of upconversion luminescence (UCL) in NaYF4:Yb(3+),Tm(3+) nanoparticles excited simultaneously by 980 nm and 1550 nm lasers. The UCL intensity is greatly depleted, while the downshifted emission at 1210 nm is obviously enhanced. The disturbances of 1550 nm photons on energy transfer between Yb(3+) and Tm(3+), cross relaxation (CR), the thermal effect and the stimulated emission depletion (STED) process are qualitatively evaluated. Our investigations verify that the unexpected depletion phenomena are governed by the STED process...
July 21, 2017: Physical Chemistry Chemical Physics: PCCP
Chao Mei, Feng Li, Jinhui Yuan, Zhe Kang, Xianting Zhang, Binbin Yan, Xinzhu Sang, Qiang Wu, Xian Zhou, Kangping Zhong, Liang Wang, Kuiru Wang, Chongxiu Yu, P K A Wai
Parabolic pulses have important applications in both basic and applied sciences, such as high power optical amplification, optical communications, all-optical signal processing, etc. The generation of parabolic similaritons in tapered hydrogenated amorphous silicon photonic wires at telecom (λ ~ 1550 nm) and mid-IR (λ ≥ 2100 nm) wavelengths is demonstrated and analyzed. The self-similar theory of parabolic pulse generation in passive waveguides with increasing nonlinearity is presented. A generalized nonlinear Schrödinger equation is used to describe the coupled dynamics of optical field in the tapered hydrogenated amorphous silicon photonic wires with either decreasing dispersion or increasing nonlinearity...
June 19, 2017: Scientific Reports
Hyeongrak Choi, Mikkel Heuck, Dirk Englund
We propose a photonic crystal nanocavity design with self-similar electromagnetic boundary conditions, achieving ultrasmall mode volume (V_{eff}). The electric energy density of a cavity mode can be maximized in the air or dielectric region, depending on the choice of boundary conditions. We illustrate the design concept with a silicon-air one-dimensional photon crystal cavity that reaches an ultrasmall mode volume of V_{eff}∼7.01×10^{-5}λ^{3} at λ∼1550  nm. We show that the extreme light concentration in our design can enable ultrastrong Kerr nonlinearities, even at the single-photon level...
June 2, 2017: Physical Review Letters
Krishna C Balram, Marcelo I Davanço, B Robert Ilic, Ji-Hoon Kyhm, Jin Dong Song, Kartik Srinivasan
Acoustic wave devices provide a promising chip-scale platform for efficiently coupling radio frequency (RF) and optical fields. Here, we use an integrated piezo-optomechanical circuit platform that exploits both the piezoelectric and photoelastic coupling mechanisms to link 2.4 GHz RF waves to 194 THz (1550 nm) optical waves, through coupling to propagating and localized 2.4 GHz acoustic waves. We demonstrate acousto-optic modulation, resonant in both the optical and mechanical domains, in which waveforms encoded on the RF carrier are mapped to the optical field...
February 2017: Physical Review Applied
Hidetaka Terasawa, Freddy Tan, Okihiro Sugihara, Akari Kawasaki, Daisuke Inoue, Tatsuya Yamashita, Manabu Kagami, Olivier Maury, Yann Bretonnière, Chantal Andraud
Light-induced self-written (LISW) optical waveguides were fabricated for the first time, to the best of our knowledge, using a photopolymerizable resin system formed by 1550 nm pulse laser light. A two-photon absorption (TPA) chromophore with a TPA cross section of several hundred Goeppert-Mayer (GM) at 1550 nm was used. Furthermore, the optical interconnection between a single-mode fiber and a fiber Bragg grating was demonstrated by the present technique, using one-way irradiation of 1550 nm laser light through the single-mode fiber...
June 1, 2017: Optics Letters
Florian Denis-le Coarer, Ana Quirce, Ángel Valle, Luis Pesquera, Marc Sciamanna, Hugo Thienpont, Krassimir Panajotov
We report an experimental study of the polarization nonlinear dynamics in a 1550 nm single-mode vertical-cavity surface-emitting laser (VCSEL) subject to parallel optical injection. Experimentally measured stability maps identifying regions of different nonlinear dynamics for various values of bias current are reported. We show that VCSELs with more than a 35 dB polarization mode suppression ratio can have rich nonlinear dynamics in both linear polarizations, including periodic and chaotic behaviors appearing simultaneously in both polarization modes...
June 1, 2017: Optics Letters
Parinaz Aleahmad, Mercedeh Khajavikhan, Demetrios Christodoulides, Patrick LiKamWa
On-chip photonic networks hold great promise for enabling next-generation high speed computation and communication systems. It is currently envisioned that future integrated photonic networks will be capable of processing dense digital information on a single monolithic platform by involving a multitude of optical components ranging from lasers to modulators, to routers, interconnects and detectors. Among the possible functionalities to be incorporated in such arrangements is the ability to route information in a unidirectional way among N-ports - a capability typically afforded through the use of optical circulators...
May 18, 2017: Scientific Reports
Reza Khazaeinezhad, Meena Siddiqui, Benjamin J Vakoc
We demonstrate a novel high-speed and broadband laser architecture based on stretched pulse active mode locking that provides a wavelength-swept and wavelength-stepped output. The laser utilizes a single intracavity 8.3 meter chirped fiber Bragg grating to generate positive and negative dispersion, and can be operated with or without an intracavity fixed Fabry-Perot etalon to generate wavelength-swept and wavelength-stepped (frequency comb) outputs, respectively. Using a four-path delay line at the output, we achieved 16...
May 15, 2017: Optics Letters
Honghui Sun, Tian Jiang, Yunyi Zang, Xin Zheng, Yan Gong, Yong Yan, Zhongjie Xu, Yu Liu, Liang Fang, Xiang'ai Cheng, Ke He
Topological insulators (TIs) are new states of quantum matter in which the spin-momentum-locked surface states reside in the bulk insulating gap and have triggered extensive investigations on fundamental properties and potential applications. Herein, we report scalable, broadband photovoltaic detectors based on the topological insulator Sb2Te3/strontium titanate (STO) heterostructure. Large-scale (2 mm × 5 mm), high crystalline quality p-type Sb2Te3 films were fabricated on an n-type STO substrate by the molecular beam epitaxy (MBE) method...
July 13, 2017: Nanoscale
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