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Photodetecctors using Si, Ge and other group IV alloys are of current interest for use at telecommunication wavelength 1550 nm. We have presented in this paper our work on resonant cavity enhanced (RCE) Si/SiGe multiple Quantum Well (MQW) and Ge Schottky photodetectors. Tensile strained Ge layers grown with suitable barriers show direct gap type I band alignment. Predicted performance of photodetectors...
We attempt to study external modulation characteristics in 1550 nm microwave over fiber links which overcome the disadvantages of light spectrum expansion and unstable optical extinction ratio because of direct modulation. The relation property between output power, threshold current and temperature is discussed at first based on physical model of a multiple quantum well-distributed feedback (MQW-DFB)...
A novel post-selection scheme is proposed to generate squeezed vacuum pulses using noisy fiber laser pulses at 1550 nm. By selecting only coherent pulses with low excess noise, quadrature squeezing is obtainable with conditional homodyne detection.
Fully integrated photonic receivers with semiconductor preamplifiers and photodiodes in a single package are demonstrated through laser-induced quantum well intermixing technology. The 1550-nm photonic integrated receivers show a sensitivity of -22.8 dBm at 20 Gb/s.
Barium titanium waveguide electro-optic modulators with Al-doped ZnO transparent conducting oxide electrodes are realized. Low half-wave voltage of 1.1 V and half-wave voltage length product of 1.1 V-cm are achieved at 1550 nm wavelength.
Squeezed vacuum up to -1.7 dB is generated with chi(3) nonlinearity caused by cascaded chi(2) nonlinearity in a quasi-phase-matched (QPM) PPLN crystal placed in a Sagnac interferometer with 1550 nm femtosecond laser pulses.
A 1310/1490/1550 nm wavelength demultiplexer consiss of two-dimensional photonic crystal is proposed. The system consists of three filters to separate the three wavelength into three different output channels. Filter 1 and 3 use circular defect scatterer and filter 2 use square defect scatterers. Square defect scatterers can increase the power transfer inside filter 2 when wavelength 1310 nm propagates...
Significant implementation challenges exist in wireless backbone connectivity. Typical optical wireless communication topologies are evaluated. A fresh approach using 1550 nm Wavelength laser to design protocol and topology for point-to-point outdoor connectivity is carried out. Matlab simulation results support the 1550 nm laser as a good choice for outdoor connectivity for optical wireless communication...
The spectral compression performance of the fundamental soliton in a dispersion-increasing fiber is investigated through numerically solving the generalized nonlinear Schrodinger equation. Based on the calculation results, we detailedly analyze the influence of the input peak power, the fiber length and the initial chirping on the output spectral width and the output center wavelength, and describe...
We present a theoretical study of the directional couplers (DCs) based on V-groove plasma waveguides with the groove angle thetas = 20deg and a wavelength of 1550 nm. DCs based-on metal grooves with different separation distance are analyzed. Curves of coupling lengths with waveguide separations are given. The normalized output power of two output ports of single-input DCs is analyzed. Finally new...
Based on Fabry-Perot structure, a multiple-channel filter is obtained in theory by changing the structure of spacer layers. This paper is concerned with the design of an optical filter, based on thin-film interference, for multichannel optical communication systems with Ta2O5 and SiO2 materials for 1550 nm operation. The variation of these parameters is also studied for various modified filter configurations...
The increase in the usage of FTTH in the optical communication has drawn much attention among the fiber optics engineers to face the challenges of sharp bends that are unavoidable at city apartment corners. In the current communication, we report experimental demonstration of the ultra-low bending loss in the single mode optical fiber. The optical fiber was fabricated using the modified chemical vapour...
The self-pulsing laser reported here was fabricated in a 92 mm long Er-diffusion doped Z-cut LN substrate with a surface concentration of about 1.24 x 1020 cm-3 and a diffusion depth of 8.4 mum. Ti stripes of 7 mum width were indiffused to define single mode waveguides for the 1550 nm wavelength range. The laser cavity was formed by two dielectric multilayer mirrors, one of them vacuum-deposited on...
Sources of entangled photon pairs serve as basis for many quantum information experiments, such as quantum computing or quantum key distribution (QKD). Especially in the field of QKD a popular wavelength combination is 810 and 1550nm, generated by spontaneous parametric down conversion (SPDC). Previous schemes facilitated two nonlinear crystals behind each other, hence limiting the propagation length...
Quantum cryptography or more specifically quantum key distribution (QKD) is the most advanced quantum information protocol. We present here an entanglement-based QKD system designed to work at 1550 nm for optimal distribution in optical fibers using the BBM92 protocol. Our QKD system is realised as a compact device. The start-up and alignment is fully automated and stabilisation routines guarantee...
A novel femtosecond Yb-fiber based amplifier seeded with a cavity-dumped Yb:KYW laser oscillator is employed for the writing of waveguides. The presented results have been achieved with a pulse energy of 1.6 muJ at 420 fs and a repetition rate of 1 MHz. We created simultaneously written waveguide pairs in fused silica with separations varying from 175 mum to 6 mum, using a 20x microscope objective...
A new snail laser geometry is modelled and presented, exhibiting stable, unidirectional lasing at both 1550 nm and 808 nm. We have calculated the fundamental mode thresholds and output power for Semiconductor Snail Laser (SSL) as a function of device parameters, i.e. coupler efficiency and output facets reflectivities. The coupler efficiency is the fraction of light transmitted between the waveguides...
A compact master-oscillator power-amplifier semiconductor laser (MOPA-SL) is a good candidate for a coherent light source (operating at 1550 nm) in a Doppler wind Lidar. The MOPA-SL requires two injection currents: Idfb for the distributed-feedback (DFB) laser section (master oscillator) and Iamp for the tapered amplifier section. The specified maximum current values are 0.7 A and 4.0 A for Idfb and...
We have identified at least five different local breakdown mechanisms according to the temperature coefficient (TC) and slope of their characteristics and electroluminescence (EL) under reverse bias. These are (1) early pre-breakdown (strongly negative TC, low slope), (2) edge breakdown (positive TC, low slope, no EL), (3) weak defect-induced breakdown (zero or weakly negative TC, moderate slope,...
High speed vertical-cavity-surface-emitting lasers (VCSELs) are attractive candidates for use in future wavelength division multiplexed passive optical network (WDM-PON). In this paper we describe a proof-of principle implementation of such a remodulation scheme with a directly modulated VCSEL array. Although a discrete receiver, VCSEL array and wavelength filters were used here for implementing the...
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