High-power integrated superluminescent light source

In order to increase the optical output power of semiconductor superluminescent device, a direct coupling method had been used to integrate, monolithically, the superluminescent diode with a semiconductor optical amplifier. By this means, two kinds of integrated superluminescent light source have been fabricated. High output power was obtained in pulsed operation.     

Fast wavelength-tunable multichannel switching using aself-injection seeding scheme

Wavelength-tunable switching among different channels in the range of hundreds of megahertz has been demonstrated by the self-injection seeding mechanism. The different wavelength components have been switched by sequentially feeding back the temporally separated cavity modes to the laser diode. The spacing between different wavelengths has been tuned by adjusting the electrical modulation frequency and the length of the dispersive fiber cavity. In addition to the spectral and temporal profiles, the switching characteristics such as the output pulsewidth, side-mode-suppression ratio, tuning rate, and the effect of the fiber length have also been investigated     

谐振式集成光学角速率传感器光源的研究

文中对谐振式集成光学角速率传感器(IORS)关键器件之一--大功率、窄线宽光源进行的分析与实验表明,为达到优于1(°)/h的分辨率,光源的线宽应小于300kHz;在实验研究中采用大功率、窄线宽的半导体激光器(LD)泵浦Nd:YAG激光器和光纤光栅外腔半导体激光器(FBG-LD)作为光源,分别应用于保偏光纤谐振腔构成的IORS的实验装置,实测谐振腔的清晰度与理论计算值是一致的.     

面向大功率LED集成光源的反射器设计方法

分析了传统光学设计方法中将LED光源近似为理想点光源的设计方法的局限性,基于非成像光学中的边缘光线理论,提出了一种面向大功率LED集成光源的均匀照明反射器的光学设计方法,在集成光源与接收面上点的照度之间建立了一种能量对应关系,得到了可以在照明面上实现均匀照度分布的反射器光学模型,最后运用光学仿真软件进行了仿真,并与点光...     

A subnanosecond integrated switching circuit with MESFET's for LSI

Using a simple channel implantation step, the choice of the threshold voltage determines speed and power. Illustrations are given by the example of a 3-input NOR-gate with 1/spl times/5-/spl mu/m/SUP 2/ channel geometry for the switching transistors. A design with dual threshold voltages allowing the optimization of power consumption while keeping subnanosecond propagation delay times is presented and applied to a speed- and power-optimized dual-type MESFET NOR-gate. Examples are presented of experimental d.c. characteristics measured on fabricated samples exhibiting an average power consumption of 150 /spl mu/W. A propagation delay time of 0.8 ns is deduced for a fan-out of 3. This performance is discussed in conjunction with a set of parameters including geometry, technological reproducibility, and circuit design requirements. It appears that geometries of about 1 /spl mu/m lead to the best compromise for fast switching and optimized LSI organization.     

Subnanosecond wavelength-tunable heterodyne receiver and analysis of its fundamental switching speed

We experimentally demonstrate subnanosecond tunability of a heterodyne receiver employing a fast-switching local laser oscillator. A <0.7-ns switching time and the feasibility to achieve hitless switching are demonstrated. Theoretical analysis of the transition process indicates that switching time shorter than a single bit slot can be realized in a typical receiver configuration with a fast-switching local oscillator.     

LED伏安特性随X射线辐照的变化

测量Ｘ射线辐照对发光二极管正向电压和反向击穿电压的影响。分析了由Ｘ射线辐照引起ＬＥＤ伏安特性变化的机理。实验结果表明一定剂量Ｘ射线辐照有助于改善器件电学特性     

A high-performance switch fabric for integrated circuit and packet switching

This paper describes an architecture for a high-performance switching fabric that can accommodate circuit-switched and packet-switched traffic in a unified manner. The switch fabric is self-routeing and uses fixed-length minipackets within the switching fabric for all types of connections. Its kernel architecture is based on a routeing topology with individual connection paths from all inputs to all outputs and with FIFO queuing at each output. Owing to the disjoint connection paths, there is no internal blocking, and because of output queueing, output port blocking is prevented to a great extent. The uniformity in architecture allows construction of any size fabric from a single basic module which could be realized on a single chip. Larger-size configurations can be realized either as single-stage or multistage configuration. The second part of this paper discusses performance aspects and gives results and dimensioning guidelines for both circuit-switched and packet-switched traffic.     

A taxonomy of broadband integrated switching architectures

A nomenclature describing a set of essential dimensions or characteristics germane to integrated broadband switching architectures is presented. Using this vocabulary, a classification of switching architectures is proposed. The classification is intended to afford the switch designer an ordered and reasoned approach to deciding among the numerous choices in the design of broadband switches     

A programmable integrated digital controller for switching converters with dual-band switching and complex pole-zero compensation

The design of a 0.6-/spl mu/m CMOS programmable integrated digital PID controller for a buck converter is presented. Several novel features are implemented. These include: 1) a dual-band switching scheme for sampling the output voltage for better output resolution; 2) a dual-band switching PWM generator with a modified tapped delay line for area efficiency; 3) a VCO driving a counter to serve as an ADC; 4) a programmable PID compensator employing variable integration times for enhancing accuracy and stability; and 5) complex pole-zero cancellation in extending the bandwidth of the control loop. The converter is designed for variable output applications, and the fast digital loop achieves a tracking time of 50 /spl mu/s for a 1-V step change of the reference voltage. The converter switches at 1 MHz and attains a maximum efficiency of 90% when delivering a load of 125 mW.     

ATM-based switching for the integrated broadband network

Telecommunications networks based on synchronous 64 kbit/s channels are too restrictive for the future realisation of integrated broadband networks. New switching and transmission techniques, particularly those based on asynchronous transfer modes (ATM), are required. Roke Manor Research Ltd. and Plessey Research Caswell Ltd. are actively developing these new techniques at a system and technology level under the auspices of the European Commission's RACE programme. The authors introduce the issues pertinent to ATM, highlighting the system and technology aspects of the work being carried out within a RACE project entitled `Broadband Local Network Technology' (BLNT) and also describes previous ATM work relevant to the current research activities     

Agile and fast switching monolithically integrated four wavelengthselectable source at 1.55 μm

We demonstrate 4-nm spaced four emitted wavelengths on a single output waveguide in a four channel DBR lasers array monolithically integrated with a 4>1 coupler. Using distributed Bragg reflector tunability, all wavelengths within a 16-nm range can be reached with an accuracy better than 0.2 nm. Wavelength switching time measured at 90% of nominal power is 4 ns     

Fast and stable frequency switching employing a delayed self-duplex(DSD) light source

A novel frequency-agile light source, the delayed self-duplex (DSD) light source, is constructed using a tunable DBR laser and an optical switch. The DSD light source overcomes the tuning speed limitation of the tunable laser, and also offers suppressed frequency drift due to the thermal effect by employing periodic laser tuning. For 160-GHz-spaced frequency switching, the 4-ns switching time and 2.2-GHz thermal frequency drift inherent to the DBR laser are reduced to 0.4 ns and 0.3 GHz, respectively     

Continuously wavelength-tunable MQW fabry-perot laser diode pulse source with a fiber-based external cavity

A simple continuously wavelength-tunable fiber ring laser pulse source is demonstrated. Such a source employs a gain-switched multiple quantum-well Fabry-Perot laser diode in a self-seeding scheme and the output pulse wavelength can be tuned continuously via a tunable optical filter. The optical pulses generated exhibit a pulsewidth of 92 ps at the frequency of 2.6 GHz. Within a wide wavelength tuning range of 46 nm, the side-mode suppression ratio and the average power of the output optical pulses obtained are higher than 50.1 dB and 3.3 dBm, respectively, and the pulse spectral stability can be maintained in the whole wavelength tuning range.     

Delayed self-multiplex light source for frequency-agiletransmitters

The delayed self-multiplex (DSM) light sources proposed in this paper provide multiple frequency-agile outputs from a single tunable laser. The DSM light source employs multiple fiber delay lines and optical switches, and overcomes the intrinsic tuning-speed limitation and thermal frequency drift of the tunable laser. Practical switching performance restricted by the optical switch is analyzed and examined in a delayed self-duplex (DSD) light source constructed with a tunable DBR laser and a LiNbO₃ electrooptic switch. Bit-error-free operation of the frequency-agile transmitter is achieved in 622 Mb/s transmission; the power penalty due to the DSD light source is 1.8 dB     

The ideal light source for datanets

The appetite for ever increasing computing power and interconnection bandwidth could be sated by vertical-cavity, surface-emitting lasers (VCSEL) for optical data communication. Made inexpensively using IC processing techniques, they can be diced in planar or linear arrays, such as in the wavelength-division multiplexer. The author discusses the essentials of semiconductor light sources, epitaxial growth of the surface-emitting laser and its interior design. The characteristics and operation of the VCSEL are described     

基于集成量子压缩光源的量子增强多普勒激光雷达（特邀）

传统激光雷达探测灵敏度不断提高,但仍然受激光光源的量子噪声以及探测端引入的额外噪声等因素限制。为了进一步提高激光雷达的探测性能,提出利用量子压缩态光场作为激光雷达的本振信号提高激光雷达探测精度的新方案,分析了所提出方案提高激光雷达探测精度的关键因素。制备了集成化低噪声压缩态光场并进行了激光雷达多普勒信息测量实验。实验结果表明,相较于传统相干多普勒激光雷达探测方案,所提方案实现了多普勒信息探测灵敏度3 dB的提升,为量子激光雷达中多普勒信息等微弱信号的探测提供研究途径。     

Monolithically integrated high-speed light source using 1.3-µm wavelength DFB-DC-PBH laser

The first monolithic high-speech light source, consisting of an InGaAsP/InP DFB laser, metal-insulator-semiconductor field-effect transistors, and a monitoring photodiode, has been fabricated. Small-signal modulation bandwidth up to 4 GHz was successfully achieved. The device design, fabrication procedures, and operating characteristics for the integrated light source are described.     

Link selection based on switching between full‐duplex and half‐duplex modes

Multiple‐input multiple‐output systems can achieve a full sum rate (SR) via full duplex (FD). However, its performance is degraded by self‐interference (SI) that occurs between the transmitter and receiver at the same node and thus is constrained by error floors. Conversely, half duplex (HD) can avoid the SI albeit at lower spectral efficiency, and the slope of its error curve is determined by the diversity order. In this study, a link selection scheme based on switching between FD and HD is examined as a simple method to improve the bit error rate (BER) performance of FD systems. In the proposed link selection algorithm, either FD or HD is selected based on the received minimum distance and signal‐to‐interference plus noise ratio. Simulation results indicate that the proposed hybrid FD/HD switching system offers significant BER performance improvement when compared with that of the conventional FD and FD based on only the received minimum distance under the same fixed SR. Under relatively sufficient SI cancellation, it is demonstrated to outperform the HD with a diversity advantage in low and medium signal‐to‐noise ratio region.