Dispersion-free (de)mux with record figure-of-merit

The authors demonstrate a wavelength (de)mux that is dispersion-free and has significantly better figure-of-merit, defined as 1-dB bandwidth over 20-dB bandwidth, over existing devices. A four-channel demux has been fabricated and the figure-of-merit is 97%. A practical system application of this device has also been demonstrated.     

11.6-GHz 1:4 regenerating demultiplexer with bit-rotation controland 6.1-GHz auto-latching phase-aligner ICs using AlGaAs/GaAs HBTtechnology

The authors present an 11.6-GHz 1:4 regenerating demultiplexer (demux) and a 6.1-GHz phase aligner, implemented using high-current-gain baseline AlGaAs/GaAs heterojunction bipolar transistor (HBT) technology. The demux features a hybrid tree/shift register-type architecture optimized for high-speed and low-power operation, and is the fastest demux with bit-rotation control ever reported. It consumes 1.4 W of power with a single -5 V supply, and has a phase margin of 270° and differential input data sensitivity of 56 mV_p-p at 11.6 Gb/s. The phase aligner incorporates an auto-latching scheme which allows the data to be latched using a timing signal derived on-chip from the data, and is the fastest fully monolithic phase aligner ever reported. It dissipates 0.8 W of power with a single -5 V supply and has differential input data sensitivity of 60 mV_p-p at 6.1 Gb/s     

New fabrication technique for high performance polarisationmaintaining optical fibre couplers

A simple and novel technique for fabricating polarisation maintaining optical fibre couplers is reported. This technique is different from existing approaches of polarisation coupler fabrication, in that it avoids the need to align the polarisation axis during each coupler fabrication. Both low loss and low polarisation crosstalk have been achieved     

40 Gbit/s OTDM soliton transmission over transoceanic distances

40 Gbit/s soliton transmission is achieved in a recirculating loop over 10000 km, for the first time to the authors' knowledge. With a single carrier wavelength. Propagation has been tested with and without polarisation multiplexing thanks to low polarisation dependency electroabsorption modulators for in-line control and for the time demultiplexing receiver     

Hybrid polymer/silica vertical coupler switch with <-32 dBpolarisation-independent crosstalk

A modified hybrid polymer/silica 1×2 vertical coupler switch (VCS) with a polymer gap layer and a refractive index contrast of 0.008 has been designed, fabricated and characterised. The VCS exhibits low loss, low crosstalk, low switching power, and polarisation insensitivity. Using the 1×2 VCS as a building block, a 1×8 VCS matrix has been implemented     

Wideband omnidirectional microstrip array

A compact broadband antenna having a far-field pattern similar to that of a magnetic dipole with horizontal polarisation has been designed and tested. The dimensions of this printed antenna, etched on low permittivity substrate, are 130×130 mm. The measured bandwidth, which is 52% for a VSWR of less than 2, is achieved through the utilisation of nonresonant elements     

Spectral response measurements on polarisation splitting ratio of fused-taper single-mode fibre couplers

Using a Ge PIN photodiode cooled to 77 K (?196°C) with liquid nitrogen and the lock-in amplification technique, an automatic polarisation spectral response measurement system with a measuring dynamic range of about 36 dB has been developed. It has been confirmed experimentally that the spectral response of polarisation beam-splitting ratios of fused-taper fibre couplers depend on the incident polarisation angle     

Passive integrated optical polarisation mode-splitter in lithium niobate employing a resonant metal-loaded structure

A passive polarisation mode-splitter has been demonstrated in Z-cut Y-propagating LiNbO/sub 3/ which achieves polarisation crosstalk better than -30 dB and excess loss of less than 1 dB in both polarisation states at lambda =1.52 mu m. The technique employed simplifies the design of polarisation mode splitters for arbitrary operating wavelengths and LiNbO/sub 3/ wafer orientations.<>     

Large-band periodic filters for DWDM using multiple-superimposed fiber Bragg gratings

The tight specifications of dense wavelength division multiplexing (DWDM) filters are challenging for any available technologies. In this letter, periodic transmission filters based on superimposed chirped fiber Bragg gratings are designed to have flat amplitude response and nearly constant in-band group delay. These filters should prove to be useful as interleavers and mux/demux filters in DWDM systems.     

Four-element varactor diode loaded polarisation-agile microstripantenna array

A square, varactor diode-loaded polarisation-agile microstrip patch, radiating either circular polarisation (left or right hand) or linear polarisation (in two orthogonal planes) is described. A linear array comprising four such patches has been designed. Measurements show, when operated in circular polarisation, axial ratios better than 0.5 dB and, in linear polarisation, cross-polar levels better than -20 dB     

Polarisation control for surface emitting lasers

A polarisation control method for surface emitting lasers is proposed. By preparing high refractive index films on one side of dielectric multilayer reflector walls, a differential loss for orthogonal polarisations can be provided. A GaAlAs-GaAs device was fabricated based on this design and the polarisation control has been demonstrated up to 1.4 times the threshold.<>     

Polarisation guiding in ultralong distance soliton transmission

Signal polarisation rotation due to polarisation dependent loss has been observed for the first time in an optical communications transmission system. In particular its effect as a limiting factor in solitonic polarisation multiplexed systems is discussed. An analytic expression for the degree of rotation is presented and experimentally verified. Additionally, 5 Gbit/s solitons have been transmitted a distance of 11000 km without transmission control     

Experimental 1.5 μm coherent optical fibre transmission systems

The authors consider the design requirements for 1.52 μm coherent optical fibre transmission systems. Some of the essential requirements are: narrow linewidth sources, polarisation stable transmission media, low insertion loss optical mixers and frequency tracking or phase locked local oscillators. Having been successful in reducing the linewidth of semiconductor lasers to less than 30 kHz, by using injection locking techniques, and in fabricating optical mixers with insertion losses of the order of dB, they have been able to experiment with coherent optical fibre transmission systems to assess their practicability. In this paper it will be shown that coherent systems can be operated over long lengths of conventional low loss monomode fibre without any polarisation penalty and give far better performance than direct detection systems.     

一种全CMOS工艺吉比特以太网串并-并串转换电路

本文介绍了一种单片集成的吉比特以太网串并－并串转换电路。在芯片中，模拟锁相环产生1．25GHz高速时钟（当芯片用于光纤网络，时钟速率就为1．06GHz)，同时一个10到1多路选择器完成并行数据到串行的转换。在接收端，差分输入信号依次经过均衡电路、双端－单端转换电路转换成数字信号。同时，数据和时钟提取电路提取出时钟，并将数据重新同步。最后，串并转换电路完成串行－并行转换和字节同步。实验芯片采用0．35μmSPTM CMOS工艺，芯片面积为1．92mm^2，在最高输入输出数据波特率条件下的功耗为900mW。     

New TE/TM polarisation splitter made in Ti:LiNbO/sub 3/ using X-cut and Z-axis propagation

A new TE/TM integrated polarisation splitter made on LiNbO/sub 3/ for an isotropic cut has been investigated. The principles of operation and measurement characteristics are presented. At 1.3 mu m wavelength, a polarisation extinction ratio of 25 dB has been obtained.<>     

Rugged all-fibre endless polarisation controller

A polarisation controller comprising four lengths of PM fibre wound onto piezoelectric cylinders has been produced. It is mechanically rugged, has an insertion loss of 1.5 dB, and is capable of endless control between two arbitrary time-varying states of polarisation. Polarisation control has been successfully demonstrated for the first time in a coherent optical transmission system over installed fibre     

基于AWG的OADM结构设计

光分插复用器（OADM）是实现波长上下话路、灵活配置网络资源的关键网元设备之一，因为阵列波导光栅（AWG）在成本和综合性能方面具有很大的优越性而使其成为目前最适于作为WDM复用器与解复用器以及构成OADM的关键器件，文章详细研究了基于AWG构建OADM的不同结构组成，主要研究了环回和折叠型两种结构，并给出了易于实现集成的平板形结构设计的不同方案。     

Stress effect for polarisation control of surface emitting lasers

To control the electric polarisation of output light in surface emitting (SE) lasers, the stress effect on the resonance model of SE lasers with an elliptical holed region is investigated. For the first time, polarisation switching by external stress has been observed and the relation between the polarisation characteristics and the structural dependence on stress clarified.<>     

Spin controlled optically pumped vertical cavity surface emitting laser

It is shown that the output polarisation of optically pumped vertical cavity surface emitting lasers (VCSELs) can be unambiguously controlled by the pump polarisation. The degree of the output polarisation is higher than that of the pump polarisation. It is concluded that the polarisation of VCSELs with spin polarised electrical pumping can be controlled even with low spin injection efficiencies.     

Faraday effect in single-mode optical fibre using an injection laser light source

The polarisation properties of the radiation from a double-heterostructure stripe laser have been investigated. The laser has been used as a light source for single-mode optical-fibre experiments. The high linear polarisation of the device above threshold allows a measurement of the Faraday effect to be made.