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1550 nm

Grant Walters, Edward H Sargent
Electro-optic materials that can be solution-processed and provide high crystalline quality are sought for the development of compact, efficient optical modulators. Here we present density functional theory investigations of the linear electro-optic coefficients of candidate materials cesium and methylammonium germanium halide perovskites. As with their lead halide counterparts, these compounds can be solution-processed; but in contrast, they possess the non-centrosymmetric crystal structures needed to provide a linear electro-optic effect...
February 9, 2018: Journal of Physical Chemistry Letters
K Karmisholt, A Haerskjold, T Karlsmark, J Waibel, U Paasch, M Haedersdal
The ability of laser treatment to affect wound healing and subsequently minimize scar formation has been investigated in recent years. However, no systematic review links these clinical trials. The aim of this study is to systematically review and evaluate clinical evidence for early laser intervention to reduce scar formation in studies where laser treatment were introduced less than 3 months after wounding. We searched PubMed using relevant key words in June 2017. Titles, abstracts and articles were sorted according to inclusion and exclusion criteria...
February 8, 2018: Journal of the European Academy of Dermatology and Venereology: JEADV
L C Gómez-Pavón, G J Lozano-Perera, A Luis-Ramos, J M Muñoz-Pacheco, J P Padilla-Martínez, P Zaca-Morán
In this work, the influence of induced losses on the saturable absorption by zinc nanoparticles photodeposited onto the core of an optical fiber end is reported. Samples with different losses were obtained by the photodeposition technique using a continuous wave laser at 1550 nm. The nonlinear absorption of the saturable absorber was characterized by the P-scan technique using a high-gain pulsed erbium-doped fiber amplifier. The results have demonstrated that for optical fibers with variable induced losses by deposited nanoparticles, the modulation depth increases proportionally based on the nonlinear absorption coefficient...
January 22, 2018: Optics Express
Xiaowei Guan, Hao Hu, Leif K Oxenløwe, Lars H Frandsen
Dense integration of photonic integrated circuits demands waveguides simultaneously fulfilling requirements on compactness, low loss, high nonlinearity, and capabilities for mass production. In this work, titanium dioxide waveguides with a thick core of 380 nm exhibiting a compact mode size (0.43 μm2) and a low loss (5.4 ± 1 dB/cm) at telecommunication wavelengths around 1550 nm have been fabricated and measured. A microring resonator having a 50 μm radius has been measured to have a loaded quality factor of 53500...
January 22, 2018: Optics Express
João P Moura, Richard A Norte, Jingkun Guo, Clemens Schäfermeier, Simon Gröblacher
Demand for lightweight, highly reflective and mechanically compliant mirrors for optics experiments has seen a significant surge. In this aspect, photonic crystal (PhC) membranes are ideal alternatives to conventional mirrors, as they provide high reflectivity with only a single suspended layer of patterned dielectric material. However, due to limitations in nanofabrication, these devices are usually not wider than 300 μm. Here we experimentally demonstrate suspended PhC mirrors spanning areas up to 10 × 10 mm 2 ...
January 22, 2018: Optics Express
Carlos Errando-Herranz, Sandipan Das, Kristinn B Gylfason
Polarization handling in suspended silicon photonics has the potential to enable new applications in fields such as optomechanics, photonic microelectromechanical systems, and mid-infrared photonics. In this work, we experimentally demonstrate a suspended polarization beam splitter on a silicon-on-insulator waveguide platform, based on an asymmetric directional coupler. Our device presents polarization extinction ratios above 10 and 15 dB, and insertion losses below 5 and 1 dB, for TM and TE polarized input, respectively, across a 40 nm wavelength range at 1550 nm, with a device length below 8 µm...
February 5, 2018: Optics Express
Julián L Pita, Ivan Aldaya, Paulo Dainese, Hugo E Hernandez-Figueroa, Lucas H Gabrielli
Photonic antennas are critical in applications such as spectroscopy, photovoltaics, optical communications, holography, and sensors. In most of those applications, metallic antennas have been employed due to their reduced sizes. Nevertheless, compact metallic antennas suffer from high dissipative loss, wavelength-dependent radiation pattern, and they are difficult to integrate with CMOS technology. All-dielectric antennas have been proposed to overcome those disadvantages because, in contrast to metallic ones, they are CMOS-compatible, easier to integrate with typical silicon waveguides, and they generally present a broader wavelength range of operation...
February 5, 2018: Optics Express
Guoping Lin, Rémi Henriet, Aurélien Coillet, Maxime Jacquot, Luca Furfaro, Gilles Cibiel, Laurent Larger, Yanne K Chembo
We present an experimental study of the variation of quality factor (Q-factor) of WGM resonators as a function of surface roughness. We consider mm-size whispering-gallery mode resonators manufactured with fluoride crystals, featuring Q-factors of the order of 1 billion at 1550 nm. The experimental procedure consists of repeated polishing steps, after which the surface roughness is evaluated using profilometry by white-light phase-shifting interferometry, while the Q-factors are determined using the cavity-ring-down method...
February 1, 2018: Optics Letters
Yannong Luo, Zhichao Nong, Shengqian Gao, Huamao Huang, Yuntao Zhu, Liu Liu, Lidan Zhou, Jian Xu, Lin Liu, Siyuan Yu, Xinlun Cai
We design and fabricate a low-loss silicon photonic two-dimensional grating coupler that serves to couple light between standard single-mode fibers and single-mode waveguides in the silicon-on-insulator platform and to split both orthogonal polarization states. The efficiency of the fabricated device is enhanced by a backside metal mirror and reaches a record value of -1.8  dB with a 1 dB bandwidth of 32 nm around 1550 nm. The demonstrated coupling efficiency is 2.2 dB better than the conventional two-dimensional grating coupler without a metal mirror...
February 1, 2018: Optics Letters
Ruolin Liao, Zhichao Wu, Songnian Fu, Shengnan Zhu, Zhe Yu, Ming Tang, Deming Liu
Although the linear optical sampling (LOS) technique is powerful enough to characterize various advanced modulation formats with high symbol rates, the central wavelength of a pulsed local oscillator (LO) needs to be carefully set according to that of the signal under test, due to the coherent mixing operation. Here, we experimentally demonstrate wideband LOS enabled by a fiber optics frequency comb (FOFC). Meanwhile, when the broadband FOFC acts as the pulsed LO, we propose a scheme to mitigate the enhanced sampling error arising in the non-ideal response of a balanced photodetector...
February 1, 2018: Optics Letters
Santo Mercuri, Pina Brianti, Enza Cestone, Annunziata Dattola, Steven Paul Nisticò
BACKGROUND: Laser technology provides different solutions for scar treatment from the traditional ablative lasers to the more recent fractional devices. PATIENTS AND METHODS: We present the case of a young woman treated for scars induced by severe whipping since the age of 10. She received four monthly nonablative fractional 1550 nm erbium glass laser treatments. Fluence used was 20 mJ/cm2 with 1500 microthermal zones/cm2. RESULTS: Significant improvement was documented in the color and texture of the lesion at the end of treatment and at follow-up...
February 2, 2018: Photomedicine and Laser Surgery
Xinran Dong, Haifeng Du, Zhi Luo, Ji'an Duan
A highly sensitive strain sensor based on a novel fiber in line Mach-Zehnder interferometer (MZI) was demonstrated experimentally. The MZI was realized by splicing a section of photonic crystal fiber (PCF) with the same length of thin core fiber (TCF) between two single mode fibers (SMFs). The fringe visibility of MZI can reach as high as 20 dB in air. In particular, the strain sensitivity of -1.95 pm/με was achieved within a range from 0 to 4000 με. Furthermore, the strain properties of different length of MZI was investigated...
January 18, 2018: Sensors
Yejing Dai, Xingfu Wang, Wenbo Peng, Cheng Xu, Changsheng Wu, Kai Dong, Ruiyuan Liu, Zhong Lin Wang
Cadmium sulfide (CdS) has received widespread attention as the building block of optoelectronic devices due to its extraordinary optoelectronic properties, low work function, and excellent thermal and chemical stability. Here, a self-powered flexible photodetector (PD) based on p-Si/n-CdS nanowires heterostructure is fabricated. By introducing the pyro-phototronic effect derived from wurtzite structured CdS, the self-powered PD shows a broadband response range, even beyond the bandgap limitation, from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed...
January 15, 2018: Advanced Materials
Viphretuo Mere, Rakshitha Kallega, Shankar Kumar Selvaraja
We present a novel photonic wire-to-slot waveguide coupler in SOI. The phase matching between a wire and slot mode is achieved using a mode transformer. The architecture consists of a balanced 50/50 power splitter and a tunable phase matched taper combiner forming a slot waveguide. We show a theoretical wire-to-slot coupling efficiency of 99 % is achievable and experimentally, we demonstrate a coupling efficiency of 99 % in the 1550 nm band. Based on the coupling scheme, we also show excitation of a slot mode in a slotted ring resonator and verified the excitation through the thermo-optic response of the rings...
January 8, 2018: Optics Express
Jiří Čtyroký, Juan Gonzalo Wangüemert-Pérez, Pavel Kwiecien, Ivan Richter, Ján Litvik, Jens H Schmid, Íñigo Molina-Fernández, Alejandro Ortega-Moñux, Milan Dado, Pavel Cheben
Properties of reflection and transmission spectral filters based on Bragg gratings in subwavelength grating (SWG) metamaterial waveguides on silicon-on-insulator platform have been analyzed using proprietary 2D and 3D simulation tools based on Fourier modal method and the coupled-mode theory. We also demonstrate that the coupled Bloch mode theory can be advantageously applied to design of Bragg gratings in SWG waveguides. By combining different techniques, including judiciously positioning silicon loading segments within the evanescent field of the SWG waveguide and making use of its dispersion properties, it is possible to attain sub-nanometer spectral bandwidths for both reflection and transmission filters in the wavelength range of 1550 nm while keeping minimum structural features of the filters as large as 100 nm...
January 8, 2018: Optics Express
Ramon A Martinez, Genevieve Plant, Kaiwen Guo, Brian Janiszewski, Michael J Freeman, Robert L Maynard, Mohammed N Islam, Fred L Terry, Oseas Alvarez, Francois Chenard, Robert Bedford, Ricky Gibson, Agustin I Ifarraguerri
We demonstrate an all-fiber supercontinuum source that generates a continuous spectrum from 1.6 μm to >11  μm with 417 mW on-time average power at 33% duty cycle. By utilizing a master oscillator power amplifier pump with three amplification stages and concatenating solid core ZBLAN, arsenic sulfide, and arsenic selenide fibers, we shift 1550 nm light to ∼4.5  μm, ∼6.5  μm, and >11  μm, respectively. With 69 mW past 7.5 μm, this source provides both high power and broad spectral expansion, while outputting a single fundamental mode...
January 15, 2018: Optics Letters
Axel Schönbeck, Fabian Thies, Roman Schnabel
Strongly squeezed light at telecommunication wavelengths is a necessary resource for one-sided device-independent quantum key distribution via fiber networks. Reducing the optical pump power that is required for its generation will advance this quantum technology towards efficient out-of-laboratory operation. Here, we investigate the second-harmonic pump power requirement for parametric generation of continuous-wave squeezed vacuum states at 1550 nm in a state-of-the-art doubly resonant standing-wave periodically poled potassium titanyl phosphate cavity setup...
January 1, 2018: Optics Letters
Jing-Yuan Wu, Young Tea Chun, Shunpu Li, Tong Zhang, Junzhan Wang, Pawan Kumar Shrestha, Daping Chu
Inverse photoresponse is discovered from phototransistors based on molybdenum disulfide (MoS2 ). The devices are capable of detecting photons with energy below the bandgap of MoS2 . Under the illumination of near-infrared (NIR) light at 980 and 1550 nm, negative photoresponses with short response time (50 ms) are observed for the first time. Upon visible-light illumination, the phototransistors exhibit positive photoresponse with ultrahigh responsivity on the order of 104 -105 A W-1 owing to the photogating effect and charge trapping mechanism...
January 8, 2018: Advanced Materials
Zhengyong Liu, Lin Htein, Kang-Kuen Lee, Kin-Tak Lau, Hwa-Yaw Tam
This paper presents a sensitive and large dynamic range pressure sensor based on a novel birefringence microstructured optical fiber (MOF) deployed in a Sagnac interferometer configuration. The MOF has two large semicircle holes in the cladding and a rectangular strut with germanium-doped core in the center. The fiber structure permits surrounding pressure to induce large effective index difference between the two polarized modes. The calculated and measured group birefringence of the fiber are 1.49 × 10-4, 1...
January 8, 2018: Scientific Reports
Muhammad Imran Shahzad, Mohsin Meraj, Majid Nazeer, Ibrahim Zia, Asif Inam, Khalid Mehmood, Hina Zafar
Suspended Solids Concentration (SSC) in water is related to its quality and transparency. Satellite remote sensing has proven to be an efficient means of monitoring water quality in large deltas because in situ sampling methods are costly, laborious, time consuming, and spatially constrained. In this study, the potential of Landsat's Enhanced Thematic Mapper Plus (ETM+) sensor was explored to develop a model for remote sensing-based quantification of SSC within the large, turbid Indus Delta Region (IDR, south of Pakistan)...
January 3, 2018: Journal of Environmental Management
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