A low-noise L-band EDFA with a 1500-nm Raman-pumped dispersion-compensating fiber section

This report presents a low-noise L-band erbium-doped fiber amplifier (EDFA) with a dispersion-compensating Raman amplifier. With an optimized prestage and 1500-nm Raman-pump laser diodes, the proposed EDFA achieved an internal noise figure of less than 4.5 dB over a 33-nm flat gain bandwidth within 0.5 dB at -2 dBm of large signal input power.     

Extended Pilot‐Based Coding for Lossless Bit Rate Reduction of MPEG Surround

Pilot‐based coding (PBC), which is used for lossless bit rate reduction of audio coding, has been recently proposed for MPEG Surround. We propose extended PBC for further lossless bit rate reduction of MPEG Surround. Extended PBC selects the number of pilots depending on the parameter band number and the type of spatial parameter. It then encodes the pilots and the relevant difference data. Experiments show that extended PBC is more effective than the original PBC, especially for high bit rate modes, with a negligible complexity increase on the decoder side.     

Hydrogenated amorphous silicon thin film transistor fabricated onplasma treated silicon nitride

We have demonstrated that the performance of the inverted staggered, hydrogenated amorphous silicon thin film transistor (a-Si:H TFT) is improved by a He, H₂, NH₃ or N₂ plasma treatment for a short time on the surface of silicon nitride (SiN _x) before a-Si:H deposition. With increasing plasma exposure time, the field-effect mobility increase at first and then decrease, but the threshold voltage changes little. The a-Si:H TFT with a 6-min N₂ plasma treatment on SiN_x exhibited a field effect mobility of 1.37 cm²/Vs, a threshold voltage of 4.2 V and a subthreshold slope of 0.34 V/dec. It is found that surface roughness of SiN_x is decreased and N concentration in the SiN _x at the surface region decreases using the plasma treatment     

Design and Architecture of Low‐Latency High‐Speed Turbo Decoders

In this paper, we propose and present implementation results of a high‐speed turbo decoding algorithm. The latency caused by (de)interleaving and iterative decoding in a conventional maximum a posteriori turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is from the combination of the radix‐4, center to top, parallel decoding, and early‐stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real‐time wireless communication services. The proposed scheme results in a slight degradation in bit error rate performance for large block sizes because the effective interleaver size in a radix‐4 implementation is reduced to half, relative to the conventional method. To prove the latency reduction, we implemented the proposed scheme on a field‐programmable gate array and compared its decoding speed with that of a conventional decoder. The results show an improvement of at least five fold for a single iteration of turbo decoding.     

Effects of vapor-annealed gate dielectric on the properties of zinc tin oxide transparent thin film transistors

We investigated the effects of vapor-annealed gate dielectrics on the mobility, threshold voltage, and other characteristics of bottom gate zinc tin oxide (ZTO) transparent thin film transistors (TTFTs). Here, Al₂O₃ films coated on dry oxidized Si wafers were annealed in a water vapor atmosphere before ZTO deposition and used as TTFT gate dielectrics. The vapor-annealed ZTO TTFTs exhibited 50% higher mobility than those that were not vapor annealed. This improvement in mobility is ascribed to the hydrogen passivation in the amorphous ZTO films     

A Rigorous 2D Approximation Technique for 3D Waveguide Structures for BPM Calculations

We propose a rigorous 2D approximation technique for the 3D waveguide structures; it can minimize the well‐known approximation errors of the commonly used effective index method. The main concept of the proposed technique is to compensate for the effective cladding index in the equivalent slab model of the original channel waveguide from the modal effective index calculated by the nonuniform 2D finite difference method. With simulations, we used the proposed technique to calculate the coupling characteristics of a directional coupler by the 2D beam propagation method, and the results were almost exactly the same as the results calculated by the 3D beam propagation method.     

An Approach for Segmentation of Airborne Laser Point Clouds Utilizing Scan‐Line Characteristics

In this study, we suggest a new segmentation algorithm for processing airborne laser point cloud data which is more memory efficient and faster than previous approaches. The main principle is the reading of data points along a scan line and their direct classification into homogeneous groups as a single process. The results of our experiments demonstrate that the algorithm runs faster and is more memory efficient than previous approaches. Moreover, the segmentation accuracy is generally acceptable.     

一种新型的低损耗激光单模光纤耦合器

本文报导了一种新型低损耗单模光纤的光学耦合器，叙述了应用光线矩阵法和梯度光学理论的设计方法，同时，从理论上讨论了耦合特性。     

Reconfigurable Optical Add‐Drop Multiplexer Using a Polymer Integrated Photonic Lightwave Circuit

We have developed a fully functional reconfigurable optical add‐drop multiplexer (ROADM) switch module using a polymer integrated photonic lightwave circuit technology. The polymer variable optical attenuator (VOA) array and digital optical switch array are integrated into one polymer PLC chip and packaged to form a 10‐channel VOA integrated optical switch module. Four of these optical switch modules are used in the ROADM switch module to execute 40‐channel switching and power equalization. As a wavelength division multiplexer (WDM) filter device, two C‐band 40‐channel athermal arrayed waveguide grating WDMs are used in the ROADM module. Optical power monitoring of each channel is carried out using a 5% tap PD. A controller and firmware having the functions of a 40‐channel switch and VOA control, optical power monitoring, as well as TEC temperature control, and data communication interfaces are also developed in this study.