InAIGaAs selective MOVPE growth with bandgap energy shift

We studied the bandgap energy shift by varying the SiO₂ mask width in selective MOVPE growth of InAIGaAs with almost no polycrystals on the masks. We found that the photoluminescence (PL) peak shifts toward the longer wavelength with wider mask width and narrower mesa width, where the In content is enhanced, and observed a maximum PL peak wavelength shift of 170 nm.     

A novel bidirectional CMOS transceiver for chip-to-chip optical interconnects

A novel bidirectional complementary metal-oxide-semiconductor (CMOS) transceiver for chip-to-chip optical interconnects operating at 2.5 Gb/s is proposed, which shares the common block of a receiver and a transmitter on a single chip. The share of the common block of two circuits makes it possible to save 55% or 20% of power dissipation, depending on the operating mode. The chip in 0.18-/spl mu/m CMOS technology occupies an area of 0.82/spl times/0.82 mm/sup 2/, 70% of the total area of a typical unshared transceiver chip. The transmitting and receiving modes of operation show -3-dB bandwidths of 2.2 and 2.4 GHz and electrical isolations of -28 and -40 dB, respectively.     

Power-aware transceiver design for half-duplex bidirectional chip-to-chip optical interconnects

A power-aware transceiver for half-duplex bidirectional chip-to-chip optical interconnects has been designed and fabricated in a 0.13 μm complementary metal-oxide-semiconductor （CMOS） technology. The transceiver can detect the presence and absence of received signals and saves 55% power in Rx enabled mode and 45% in Tx enabled mode. The chip occupies an area of 1.034 mm2 and achieves a 3-dB bandwidth of 6 GHz and 7 GHz in Tx and Rx modes, respectively. The disabled outputs for the Tx and Rx modes are isolated with 180 dB and 139 dB, respectively, from the enabled outputs. Clear eye diagrams are obtained at 4.25 Gbps for both the Tx and Rx modes.     

Polarization-insensitive semiconductor optical amplifier arraygrown by selective MOVPE

Polarization-insensitive 1.3 μm wavelength semiconductor optical amplifier (SOA) arrays are developed for the first time, by using a new fabrication process with selective MOVPE. In a four-channel array, the SOAs have uniform device characteristics of more than 20 dB signal gain and less than 1 dB polarization sensitivity     

All selective MOVPE grown BH-LDs fabricated by the novel self-alignment process

1.3 /spl mu/m-strained MQW BH LDs with a current blocking structure have been developed by selective MOVPE and a newly developed self-alignment process; we call these devices ASM (all selective MOVPE grown)-BH-LDs. The fabrication process, which completely eliminates semiconductor etching, is very promising to realize high-performance LDs with excellent uniformity and reproducibility. The light output power was remarkably improved by a factor of two, compared with previous selective MOVPE-LDs.     

Low drive voltage (1.5 Vp.p.) and high power DFB-LD/modulatorintegrated light sources using bandgap energy controlled selective MOVPE

The authors have reduced modulator drive voltage in DFB-LD/modulator integrated light sources (DFB/MODs) taking fabrication tolerance into account. By enhancing the quantum confined Stark effect through well width increase and optimising the doping profile, DFB/MODS with >13 dB extinction ratio at 1.5 V and >4 mW (+6 dBm) output power at 100 mA were achieved while maintaining a reasonably large fabrication tolerance     

High-extinction-ratio MQW electroabsorption-modulator integratedDFB laser fabricated by in-plane bandgap energy control technique

The local bandgap energy of an InGaAs/InGaAsP multiple quantum well (MQW) structure was precisely adjusted by in-plane Eg control in one-step selective area metalorganic chemical vapor deposition (MOCVD) growth. The technique was then applied to an MQW electroabsorption-modulator integrated distributed feedback (DFB) laser. Experimental results showed superior device characteristics, such as a high extinction ratio of 25 dB and low threshold current of 15 mA     

空间光通信的激光发射和接收技术及模拟实验

对１ ～６０ Ｍｂ／ｓ 空间光通信的激光发射和接收技术进行了研究,设计并组装了半导体激光调制驱动电路和雪崩光电二极管（ Ａ Ｐ Ｄ） 光电检测电路。模拟实验表明,其主要特性能满足小型空间光通信的要求。     

一种用于短距离无线通信的低功耗多频带可配置收发机

A reconfigurable multi-mode multi-band transceiver for low power short-range wireless communication applications is presented.Its low intermediate frequency(IF) receiver with 3 MHz IF carrier frequency and the direct-conversion transmitter support reconfigurable signal bandwidths from 250 kHz to 2 MHz and support a highest data rate of 3 Mbps for MSK modulation.An integrated multi-band PLL frequency synthesizer is utilized to provide the quadrature LO signals from about 300 MHz to 1 GHz for the transceiver multi-band application. The transceiver has been implemented in a 0.18μm CMOS process.The measurement results at the maximum gain mode show that the receiver achieves a noise figure(NF) of 4.9/5.5 dB and an input 3rd order intermodulation point(IIP3) of-19.6/-18.2 dBm in 400/900 MHz band.The transmitter working in 400/900 MHz band can deliver 10.2/7.3 dBm power to a 50Ωload.The transceiver consumes 32.9/35.6 mW in receive mode and 47.4/50.1 mW in transmit mode in 400/900 MHz band,respectively.     

激光通信与成像卡塞格林形式收发光学天线结构初解

在激光通信和成像系统中,卡塞格林形式的光学天线不论作为激光信号收发装置还是光学成像装置,像差的存在必然会降低其信号强度和成像质量等性能。通过分析三级像差理论和光学天线微扰理论,依据天线增益因子与遮挡比之间的关系,提出一种方便快捷求解卡塞格林式光学天线结构的方法。此方法在考虑光学天线效率的同时,也可以满足光学系统设计的体积尺寸、像差的要求,在仅知道光学系统焦距、主次镜间距和遮挡比的情况下,可以快捷求出光学天线结构参数。不但给出了四类卡塞格林式光学天线的光学结构参数计算公式,并且结合实际使用对不同的适用场合进行说明及优缺点对比。通过四种典型光学天线的实例计算结果和最优结果比对,表明此方法是一种方便快捷精准求解卡塞格林式的光学天线结构的方法,在工程上具实际指导意义。     

OEICs for WDM transceiver modules fabricated by reactive ion etching on semi-insulating substrates

The design and fabrication of OEICs on semi-insulating InP substrates comprising 1300 nm DFB lasers, 1300/1530 nm wavelength duplexers and monitor photodiodes is described. OEIC lasing thresholds were as low as 20 mA. The through-state crosstalk for the integrated duplexer was typically -12 dB. Linear tracking of the laser output by the monitor photodiode was achieved with sensitivities in the region of 70 mu A/mW. The OEICs operated successfully in a 622 Mbit/s bidirectional optical link.<>     

A novel bidirectional optical coupling module for subscribers

To overcome drawbacks and limitations of planar lightwave circuit based modules for bidirectional communications, such as the demand for several chips and in consequence more packaging efforts, we have recently developed a novel optical coupling technique using our unique 155 Mbps bidirectional laser chip. Since the chip is structured with a pin-photodiode monolithically integrated on a laser diode's waveguide, the optical coupling requires only the alignment of the chip with a fiber. To optically couple the laser diode and photodiode simultaneously with a single fiber, we have designed an unusual coupling structure using a fiber having a cleaved surface whose normal is 35/spl deg/ angled to the fiber core axis, and using an index-controlling medium with a refractive index of /spl sim/1.3. The bidirectional chip is flip-chip bonded and the fiber is passively aligned using a V-groove on the same substrate of 2.5/spl times/1.3 mm/sup 2/ in size. Even with this extremely small and simple scheme for bidirectional optical coupling, we could obtain an optical output power of -7/spl sim/-10 dBm and a responsivity of <-30 dBm, which are satisfactory to the STM-1 level telecommunications specifications.     

A compact coaxial-type optical transceiver module using ahalf-transmittance photodiode for TCM optical access networks

A compact coaxial-type optical transceiver module has been developed without using a conventional 3 dB optical coupler. This transceiver is composed of a newly designed half-transmittance photodiode (HT-PD) and a 1.3-μm-MQW-LD. An HT-PD is used both as a photodetector and as a window for LD light. Fiber output power of 1.15 mW at the drive current of 26 mA and responsivity of 0.48 A/W at the reverse-voltage of 5 V were obtained. Temperature dependence of responsivity is also reported     

A DIL-type miniature optical transceiver module using an InGaAsPhalf-transmittance photodiode for TCM optical access networks

A compact DIL-type miniature optical transceiver module has been developed without using a conventional 3 dB optical coupler. This transceiver is composed of a newly designed InGaAsP half-transmittance photodiode (HT-PD) and a 1.3-μm multiquantum-well laser diode (MQW-LD). An HT-PD is used both as a photodetector and as a window for laser diode (LD) light. Fiber output power of 0 dBm at the drive current of 33.8 mA and responsivity of 0.58 A/W at the reverse-voltage of 2 V were obtained. The fundamental characteristics of the HT-PD are studied and discussed     

A 2.7-V 900-MHz/1.9-GHz dual-band transceiver IC for digitalwireless communication

A 2.7-V 900-MHz/1.9-GHz dual-band transceiver IC consisting of receive, transmit, and local oscillator (LO) sections is presented. The transmit section achieves an unwanted sideband suppression of -43 dBc, LO leakage of -59 dBc, and third-order spurious rejection of -70 dBc. The transmit output noise level is -165 dBc/Hz at a 20-MHz offset from the carrier. The on-chip very high-frequency oscillator has a phase-noise level of -106 dBc/Hz at 100-kHz offset when operating at 800 MHz. The receive section has 36 dB of gain with 36 dB of gain range in 12-dB steps. The transceiver IC has been fabricated using a 25-GHz f_t silicon bipolar process and is designed to operate over a supply-voltage range of 2.7-5.0 V     

A bi-directional transceiver PIC for ping-pong local loop configurations operating at 1.3-/spl mu/m wavelength

We propose and demonstrate a simple, potentially low-cost, photonic integrated circuit that can operate as a transceiver in a ping-pong optical data-link configuration. The device is designed for uncooled operation, with a gain section, a detector, and a beam expander inside a Fabry-Perot cavity. The detector has a 1.4 /spl mu/m quaternary layer with a broad spectral responsivity range extending to 33 nm higher than the lasing wavelength of the device. The transmitter can provide 8 dBm inside a single-mode fiber, and the beam expander relaxes the alignment tolerance to a single-mode fiber.     

适应超高速光通信系统的PM-MSK调制方案

先进的调制技术可以有效地改善光通信系统抵御色散、偏振模和非线性等损伤的能力,是超高速光通信系统中的重要技术。MSK(最小频移键控)是一种恒包络调制技术,具有色散容限较大和能量集中等优点,文章将MSK调制引入PM(偏振复用)系统,提出了一种适应于超高速光通信系统的PM-MSK调制方案。理论分析和数值仿真结果表明,该方案与RZ(归零)和QPSK(正交频移键控)方案相比,具有更好的误码率性能。     

基于EPON智能电能表光通信模块的设计与实现

智能电能表光通信模块的研究,在智能电网建设中发挥着重要作用。通过对EPON(以太网无源光网络)、PLC(电力载波通信)和WiMAX(全球微波互联接入)技术的对比分析,选择EPON作为智能电能表通信接入网技术,并设计了通信流程。基于QCA8829嵌入式芯片,在Redhat Linux 2.6.x开发平台上采用可接入EPON系统的光纤接口技术,实现了智能电能表主站与从站的通信系统。经测试表明,基于EPON智能电表光通信模块实现了智能电网配电侧信息全采集、全覆盖,并使远程电费控制及负载控制到户。