摘要:

A single model for analogue fibre-optic links is presented that is applicable using either direct or external modulation. The impact of device slope efficiency and effective resistance on the link gain and noise figure is explored, and it is found that both may be improved significantly. The gain improvements may be implemented at the source or detector end of the link; the noise figure is more effectively improved at the source end. The influence on gain and noise figure of average optical power and modulator sensitivity is also examined.

DOI:10.1049/ip-j.1992.0042

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The implications on the dynamic response of a laser diode for two nonlinear gain models are studied theoretically. The nonperturbative model, recently introduced by Agrawal, leads to a quantitative difference with the previous commonly used two-level model in terms of both the intrinsic bandwidth and damping. The present work is compared with predictions made by Agrawal for the nonperturbative model.

DOI:10.1049/ip-j.1992.0043

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Efficient modulation at frequencies in excess of 1.3 GHz has been achieved in long-wavelength InGaAs/InP multiple-quantum-well reflective modulators. The devices function simultaneously as efficient high-speed detectors, with demonstrated response to 2 Gbit/s.

DOI:10.1049/ip-j.1992.0044

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A computer model for the performance of a semiconductor laser amplifier under static and dynamic input conditions is presented. In particular, the model is used to study the behaviour of the amplifier with sinusoidally intensity-modulated input signals. The distortion arising from gain modulation at low modulation frequencies is investigated. It is shown that at microwave modulation frequencies the gain takes an average value and the response becomes linear. Semiconductor laser amplifiers are therefore suitable for applications in microwave optoelectronics, such as reference signal distribution in optically controlled phased-array antennas.

DOI:10.1049/ip-j.1992.0045

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A series of investigations into the networking and signal-processing applications of 790 nm self-pulsating lasers is described. These devices, which were developed for optical disc interrogation, offer the response speed and power output expected of laser diodes but with substantially reduced coherence. This combination of properties is achieved by an appropriate cavity design which results in self-sustained, high-extinction-ratio oscillation at frequencies extending beyond 2 GHz. The resulting low-coherence emission substantially reduces modal noise in multimode fibre networks. Additionally, optoelectronic signal processing functions such as microwave injection-locking and carrier extraction are possible. We present two sets of experimental results. First, single-channel-per-laser subcarrier networking with respective aggregate throughputs of 450 Mbit/s and 1 Gbit/s over three binary phase shift keyed (BPSK) and five (quaternary phase shift keyed) QPSK channels is reported. Secondly, experimental observation of 1 GHz injection-locking together with 750 MHz and 1.5 GHz carrier extraction from BPSK and QPSK subcarrier signals centred on 375 MHz is described. Future applications for this work may be found in the areas of computer networking and optoelectronic signal-processing.

DOI:10.1049/ip-j.1992.0046

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A subcarrier multiplexing based optical wavelength division multiplexing system with fibre Brillouin amplification (FBA) is analysed. In the optical domain, a pump laser is tuned to amplify the corresponding optical carrier by FBA for the desired group of SCM signals. In the electrical domain, a microwave tuner is used to select the desired channel in the selected SCM group. This system has the benefits of eliminating the need for polarisation control, the ability to cancel phase noise due to the ‘squaring’ photodetection process of the selected optical carrier together with its SCM channels, and enhancement of optical receiver sensitivity by amplification of the carrier. Comparisons with other systems are also presented.

DOI:10.1049/ip-j.1992.0047

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A rigorous technique for the design of postdetection filters, previously applied to low-bit-rate systems, is extended to allow for practical implementation for very high bit rates. This has been accomplished by realising the filters as microstrip structures. Two alternative optimisation techniques are explored, one based on the optimisation of an ideal-transmission-line structure followed by the application of CAD tools, and the other based on the direct optimisation of microstrip lines. Owing to the shortcomings of the public domain microstrip models, the approach based on ideal transmission lines is identified as most appropriate. Simulated system results are presented to illustrate the performance benefits that this approach can offer to very high-bit-rate optical communication systems.

DOI:10.1049/ip-j.1992.0048

出版商:IEE    

年代:1992

数据来源: IET

摘要:

Optical techniques for microwave signal generation and optical control of microwave devices are described. Optical generation of microwave signals to 35 GHz and above by coherent heterodyne was carried out by FM sideband injection locking of laser diodes and by offset frequency phase locking of solid state lasers. Applications of optically generated microwave signals including optical control of phased array radar and photodetector characterisation are discussed. Optical injection locking, phase control, and phase locking of microwave oscillators are also presented.

DOI:10.1049/ip-j.1992.0049

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The paper presents some new methods of optical-microwave phase detection offering new ways to improve the performance of the optical transmission of microwave signals. Optical-microwave phase detection can be accomplished by a direct or an indirect method. Both methods are discussed in detail. The operation of the phase detector has been investigated utilising an experimental circuit composed of discrete elements. The measured results are in a good agreement with the theoretical results.

DOI:10.1049/ip-j.1992.0050

出版商:IEE    

年代:1992

数据来源: IET

摘要:

An optical beam-forming network with coherent optical phase shifting was designed for a telecommunications satellite with a 160-subarray phased-array antenna. The antenna generates 15 spot beams for simultaneous transmit (12.5–12.75 GHz) and receive (14–14.5 GHz) with up to twenty 33 or 72 MBit QPSK modulated carriers. The proof-of-concept model (PCM) for the transmit part is realised with two QPSK channels. The phase and amplitude weighting section can control five subarrays. The links to two subarrays are included. The optical phase shift technique offers many advantages over electronic implementation, including savings in mass and power consumption.

DOI:10.1049/ip-j.1992.0051

出版商:IEE    

年代:1992

数据来源: IET