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1550 nm

Chunlei Sun, Yu Yu, Xinliang Zhang
We propose and experimentally demonstrate an ultra-compact multimode waveguide crossing that can process two modes simultaneously. The symmetric Y-junction is introduced to split the high-order modes into fundamental ones, easing the subsequent processing. The footprint of the proposed crossing is as compact as 21  μm×21  μm. The measured results show an insertion loss of ∼1.82  dB for the TE0 mode and ∼0.46  dB for the TE1 mode at 1550 nm, as well as a crosstalk of <-18  dB from 1510 to 1600 nm...
December 1, 2017: Optics Letters
Quandong Huang, Wei Jin, Kin Seng Chiang
We propose a mode switch that operates on modulating the optical phases of a three-dimensional balanced four-arm waveguide Mach-Zehnder interferometer. We design and fabricate the device with polymer material to achieve thermo-optic switching between any two of the E11, E21, E12, and E22 modes of the waveguide. Our experimental device shows an extinction ratio higher than 14 dB and a switching time shorter than 3.7 ms, measured with the E11 mode switched to any of the other modes at 1550 nm. This mode switch can operate over a wide range of wavelengths with weak polarization dependence and could be used in reconfigurable fiber-based mode-division-multiplexing systems where mode routing is required...
December 1, 2017: Optics Letters
Chung-Lun Wu, Jen-Yang Huang, Ding-Hsin Ou, Ting-Wei Liao, Yi-Jen Chiu, Min-Hsiung Shih, Yuan-Yao Lin, Ann-Kuo Chu, Chao-Kuei Lee
The Ta2O5-based micro-ring resonator with an unloaded quality factor of 182,000 has been demonstrated to realize efficient nonlinear wavelength generation. The propagation loss of the resonator is 0.5  cm-1, and the buildup factor of the ring resonator is estimated to be ∼50. With a high buildup factor of the ring structure, the four-wave-mixing (FWM) conversion efficiency of -30  dB is achieved in the resonator with a pump power of 6 mW. Based on power-dependent FWM results, the nonlinear refractive index of Ta2O5 is estimated to be 1...
December 1, 2017: Optics Letters
Qinyu Qian, Changqing Xu, Chinhua Wang
We report on an all-dielectric, polarization-independent angular filter with one-dimension (1D) photonic crystal (PC) composed of semiconductor compatible Si/SiO2 pairs. The near-symmetric directional band gap of p- and s-polarized components and Fabry-Pérot (F-P) resonances are utilized to realize efficient polarization-independent angular filtering for normal incidence. The proposed angular filter is designed and experimentally demonstrated in a large area (5 cm × 5 cm) with multilayer sputtering depositions...
November 29, 2017: Scientific Reports
Junku Liu, Nan Guo, Xiaoyang Xiao, Kenan Zhang, Yi Jia, Shuyun Zhou, Yang Wu, Qunqing Li, Lin Xiao
In this study, we fabricate air-stable p-type multi-layered MoTe2 phototransistor using Au as electrodes, which shows pronounced photovoltaic response in off-state with asymmetric contact form. By analyzing the spatially resolved photoresponse using scanning photocurrent microscopy, we found that the potential steps are formed in the vicinity of the electrodes/MoTe2 interface due to the doping of the MoTe2 by the metal contacts. The potential step dominates the separation of photoexcited electron-hole pairs in short-circuit condition or with small V sd biased...
November 22, 2017: Nanoscale Research Letters
Yun Wang, Timothy Lee, Francesco De Lucia, Muhammad I M Abdul Khudus, Pier J A Sazio, Martynas Beresna, Gilberto Brambilla
We simulate and experimentally demonstrate deep ultraviolet generation from a 1550 nm laser source in a fully fiberized system by cascading second- and third-harmonic generation using a periodically poled silica fiber and an optical sub-micron diameter fiber. Harmonic generation is achieved by harnessing intermodal phase matching in optical microfibers and a permanent χ((2)) induced via thermal poling. As a result, efficient nonlinear processes can be observed, despite the low third-order nonlinear susceptibility of silica glass...
November 15, 2017: Optics Letters
Peng Bai, Y H Zhang, W Z Shen
High performance single photon detector at the wavelength of 1550 nm has drawn wide attention and achieved vast improvement due to its significant application in quantum information, quantum key distribution, as well as cosmology. A novel infrared up-conversion single photon detector (USPD) at 1550 nm was proposed to work in free-running regime based on the InGaAs/ InP photodetector (PD)- GaAs/AlGaAs LED up-converter and Si single photon avalanche diode (SPAD). In contrast to conventional In0.53Ga0.47As SPAD, the USPD can suppress dark count rate and afterpulsing efficiently without sacrificing the photon detection efficiency (PDE)...
November 10, 2017: Scientific Reports
O Eyal, A Willinger, S Banyoudeh, F Schanbel, V Sichkovskyi, V Mikhelashvili, J P Reithmaier, G Eisenstein
We report on high quality InAs/InP quantum dot optical amplifiers for the 1550 nm wavelength range operating over a wide temperature range of 25 to 100 °C. A temperature dependent shift of the peak gain wavelength at a rate of 0.78 nm/K is observed. Consequently, two possible modes of operation are performed for a systematic device characterization over the entire temperature range. In the first mode, the signal wavelength is tuned to always match the peak gain wavelength while in the second mode, the signal wavelength is kept constant as the gain spectrum shifts with the temperature...
October 30, 2017: Optics Express
Ramin Djabery, Mohammad Naser-Moghaddasi, Alireza Andalib
In this paper, a polarization modulator is proposed, based on surface plasmons in a 1550 nm window. Following the generalized Snell's law, the meta-surface for converting an incident propagating wave to a surface wave is carefully designed with nearly 84% efficiency. Moreover, the coupling ratio for TE and TM polarization of the incident wave is calculated. Furthermore, the LiNbO3 structure is used as a polarizer. Finally, the calculations are verified by employing the rigorous numerical finite-difference time-domain simulation method, and the results are found to be in excellent agreement...
November 1, 2017: Applied Optics
Fengqiang Li, Joshua Yablon, Andreas Velten, Mohit Gupta, Oliver Cossairt
Lasers and laser diodes are widely used as illumination sources for optical imaging techniques. Time-of-flight (ToF) cameras with laser diodes and range imaging based on optical interferometry systems using lasers are among these techniques, with various applications in fields such as metrology and machine vision. ToF cameras can have imaging ranges of several meters, but offer only centimeter-level depth resolution. On the other hand, range imaging based on optical interferometry has depth resolution on the micrometer and even nanometer scale, but offers very limited (sub-millimeter) imaging ranges...
November 1, 2017: Applied Optics
Animesh Bala, Kanan Roy Chowdhury, Md Borhan Mia, Mohammad Faisal
A triangular lattice dispersion compensating photonic crystal fiber is presented in this paper. The fiber produces high birefringence and operates at fundamental mode only. The full vector finite element method with a perfectly matched absorbing layer boundary condition is applied to investigate the guiding properties of the proposed fiber. The designed fiber demonstrates that it is possible to obtain a very large negative dispersion of -9486.1  ps/(nm·km) at 1550 nm wavelength with a negative dispersion more than -7000  ps/(nm·km) over the entire C-band (1530-1565 nm), which is suitable for broadband dispersion compensation...
September 1, 2017: Applied Optics
Donghai Niu, Shiqi Sun, Qiang Xu, Minghui Jiang, Xibin Wang, Zhiyong Li, Changming Chen, Yuanda Wu, Daming Zhang
In this paper, the power-consumption characteristics of a polymeric thermo-optic (TO) switch consisting of a silica under-cladding on silicon substrate, a polymer core surrounded with polymer upper-cladding, and aluminum heating electrodes with different widths were investigated. Norland optical adhesive 73 with a larger TO coefficient was selected as the core layer, which could reduce the power consumption effectively. The silica under-cladding, with large thermal conductivity, could shorten the response time...
July 20, 2017: Applied Optics
Mehdi Hassani Keleshtery, Hassan Kaatuzian, Ali Mir, Ashkan Zandi
We demonstrate the analogue of electromagnetically induced transparency (EIT) in a metal-dielectric-metal (MDM) plasmonic waveguide. Plasmonic induced transparency is a method similar to EIT. In this paper, a plasmonic MDM waveguide is proposed by using an ellipse shaped side-coupled ring resonator and simulated by finite difference time domain. Plasmonics as a new field of chip-scale technology is an interesting substrate, which is used to propose and numerically investigate a novel MDM structure. The aforementioned framework is a 2×2 plasmonic ring resonator, employing gold as a metal and polymethyl methacrylate as a dielectric...
May 20, 2017: Applied Optics
Michael C Brupbacher, Dajie Zhang, William M Buchta, Marc B Airola, David M Brown, Michael E Thomas, James B Spicer
This study presents results for the high-temperature (up to 1550 K) optical properties of polycrystalline Cr-doped α-alumina materials. Diffuse reflectance spectra in the wavelength range of 510-840 nm are presented as a function of temperature to illustrate changes to the optical behavior of these materials including a previously unreported thermally activated splitting of the U-band absorption (A24→T24) in octahedrally coordinated Cr(3+). Measurements were made using a unique laser-based approach for high-temperature solid-state spectroscopy, involving front-side supercontinuum laser illumination and back-side CO2 laser heating...
September 20, 2017: Applied Optics
S Bhardwaj, K Mittholiya, A Bhatnagar, R Bernard, J A Dharmadhikari, D Mathur, A K Dharmadhikari
We describe two types of waveguides (type I and depressed cladding) inscribed in lithium niobate using a variable repetition rate (200 kHz-25 MHz), 270 fs duration fiber laser. The type I modification-based waveguides have propagation losses in the range from 1.2 to 10 dB/cm at 1550 nm, depending on experimental parameters. These waveguides are not permanent; they deteriorate over time. Such deterioration of waveguides can be slowed down from 30 days to 100 days by pre-annealing the samples and by writing at a 720 kHz laser repetition rate...
July 10, 2017: Applied Optics
Wanwan Liu, Yifu Chen, Xin Hu, Long Wen, Lin Jin, Qiang Su, Qin Chen
Non-metallic plasmonic materials have recently attracted research interest due to their adjustable plasmonic material properties and the potential low loss, which is important to plasmonic waveguides with ultrahigh mode confinement. In this paper, we analyzed the mode properties of four types of plasmonic waveguides based on noble metals, aluminum-zinc-oxide (AZO), and TiN, where the propagation length and mode size are chosen to compare the figures of merit. It is found that AZO has the smallest imaginary part of permittivity in the near-infrared region, while AZO waveguides have propagation lengths comparable to those of Cu waveguides but shorter than those of Au and Ag waveguides...
June 1, 2017: Applied Optics
Konstantin Gorbachenya, Viktor Kisel, Anatoly Yasukevich, Pavel Loiko, Xavier Mateos, Viktor Maltsev, Nikolai Leonyuk, Magdalena Aguiló, Francesc Díaz, Uwe Griebner, Valentin Petrov, Nikolai Kuleshov
A single-layer graphene saturable absorber is employed for passive Q-switching of an Er, Yb:GdAl3(BO3)4 (Er,Yb:GdAB) compact laser, representing the first Er-doped oxoborate laser Q-switched by graphene. This laser is based on a c-cut 1.8 at. % Er(3+), 15 at. % Yb(3+):GdAB crystal diode-pumped at 0.976 μm. It generates a maximum average output power of 360 mW at 1.55 μm with a slope efficiency of 23% (with respect to the incident power). Stable ∼1  μJ/130  ns pulses are achieved at a repetition rate of 400 kHz...
June 1, 2017: Applied Optics
Xiaobo Hu, Juanjuan Xue, Jiao Tian, Guoen Weng, Shaoqiang Chen
The effect of the Cu/Ga ratio on properties of deep-level defects in CuGaSe2 thin films were studied, using photocapacitance methods with two-wavelength excitation. The transient photocapacitance method, using a monochromatic probe light, determined two kinds of defects located at 0.8 eV and 1.5 eV above the valence band, respectively, the positions of which kept almost constant regardless of Cu/Ga ratio. In addition to the probe light, laser light with a wavelength of 1550 nm corresponding to 0.8 eV was then used to study the saturation effect of the deep-level defect at 0...
May 10, 2017: Applied Optics
Chia-Ti Wu, Chia-Chih Huang, Yeun-Chung Lee
In this paper, we propose a novel wavelength demultiplexer based on metal-insulator-metal plasmonic waveguides with a nanoscale ring resonator. Its transmission characteristics are numerically studied using finite element method (FEM) simulations, and the eigenwavelengths of the ring resonator are theoretically calculated. For the proposed structure, we found that the ratio of the orders of resonant transmittance peaks for two different high-order modes of the ring resonator is close to the ratio of the two communication wavelengths 1310 and 1550 nm...
May 10, 2017: Applied Optics
Yin-Jung Chang, Ren-Wei Feng
The theoretical formulation based on rigorous transmission-line networks is developed for a general mode conversion problem and lays the groundwork for a simpler yet more efficient graphical design approach for hybrid plasmonic mode converters (HPMCs). The concurrence of co- and cross-polarization conversion to and among higher-order photonic and HP modes followed by subsequent power redistributions and losses over the course of the HPMC can lead to performance degradation and largely determines the silicon core thickness...
July 1, 2017: Applied Optics
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