摘要:

In the paper, the conceptual scheme of a LiNbO3integrated optical circuit for on-board data processing is proposed. The design of each integrated component and fabrication techniques are discussed. Finally, a simulation of the whole circuit performance is presented.

DOI:10.1049/ip-j.1990.0061

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An alternative approach that directly obtains the dispersion equation for each mode of a multilayered integrated optic waveguide is presented. The form of the dispersion equation can be easily numerically implemented; the presence of a single solution greatly simplifies the roots finding. This new approach does not present any limitation even dealing with almost degenerate modes, with leaky or lossy structures.

DOI:10.1049/ip-j.1990.0062

出版商:IEE    

年代:1990

数据来源: IET

摘要:

A unified study of the noise and modulation characteristics of Fabry-Perot and DFB semiconductor lasers with arbitrary external optical feedback and arbitrary external cavity length is presented. By performing a small-signal analysis and taking into account the nonlinear gain saturation effect, generalisations of previous analytical results and novel features are presented in the following topics: intensity and frequency noise, intensity and frequency modulation responses, chirp reduction, frequency and damping rate of relaxation oscillations.

DOI:10.1049/ip-j.1990.0063

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Nowadays, the jitter computation in direct detection optical fibre communications is very important for the use of very high transmission bit rates in these systems. To compute the jitter it is necessary to describe the output process of the direct detection optical receiver in the whole time domain. This can be done through the marked and filtered Poisson process (MFPP) model. However, this model leads to some difficult jitter computation. So, it is convenient to use an approach that simplifies these calculations. A generalised gaussian approach for the output process of a binary direct detection optical receiver is developed. In this approach, every independent component of the output process is considered as a normal process with the first and second order moments equal to the respective moments of the MFPP model. For the information signal component, each process associated with each state is normal. When the moment generating function of the photodiode gain is well described by the first three terms of the MacLaurin series expansion, it is shown that this approach represents the output process correctly. It is shown also that, in the sampling instant and for the worst case of symbol sequence, it leads to the signal to noise ratio approach, presented by Personick to compute the receiver sensitivity.

DOI:10.1049/ip-j.1990.0064

出版商:IEE    

年代:1990

数据来源: IET

摘要:

Nowadays, people are using very high transmission bit rates (multigigabit per second) to exploit the full bandwidth of single-mode fibre in direct detection optical fibre communications. Hence, it is convenient to develop efficient analytical tools to compute the jitter arising in multigigabit systems. These analytical tools may be generalised to the study of jitter inherent in laser transmitters. A general analytical method based on the moment generating function (MGF) was developed to compute and optimise the jitter performance in optical fibre regenerators. It is capable of dealing with any type of prefilter, nonlinearity, linear narrow band-pass filter, photo-detector device, optical pulse shape, output filter pulse shape and line-code. In this paper, we analyse the influence of circuit, quantum signal and dark current noises on jitter performance in binary direct detection optical receivers. It is seen that, in terms of jitter performance and with low signal to noise ratio, an APD, with quantum signal noise dominance, presents the best choice; a PIN, in which the circuit noise is dominant, is the next preferred choice and a Ge APD, with the dark current noise dominance, is the worst choice. The results obtained with application of this method allow the development of design rules for the optical receivers.

DOI:10.1049/ip-j.1990.0065

出版商:IEE    

年代:1990

数据来源: IET

摘要:

New methods are developed for evaluating the average error probability in the presence of crosstalk for direct detection wavelength division multiplexed systems. A specific objective is the identification of soundly based performance evaluation tools adequately accommodating signal dependent noise, or compound randomness, encountered with systems incorporating optical amplifiers or avalanche photodiode receivers. To this end, explicit moment generating functions (MGFs) for the random processes, including crosstalk, are developed and incorporated into formulations based on a modified Chernoff bound (MCB) and saddlepoint approximation (SAP). The latter is used primarily to examine the tightness of the former, more readily applicable technique. Specific results are presented to illustrate the application of these new techniques. These indicate that signal to interference ratio (SIR) of some 15.2 dB is required for a PIN receiver if per formance is to be maintained unimpaired by crosstalk with a bit error rate (BER) of 10−9. In contrast, for an APD receiver a slightly greater SIR is required, an SIR of 16.4 dB being found to be necessary for an APD gain of 10, for example.

DOI:10.1049/ip-j.1990.0066

出版商:IEE    

年代:1990

数据来源: IET

摘要:

The relative intensity noise (RIN) and the linewidth of a PCM-modulated single-mode laser diode with moderate optical feedback within the coherence collapse regime has been investigated. The results are used to characterise the performance of a directly modulated PCM-optical system with arbitrary optical feedback.

DOI:10.1049/ip-j.1990.0067

出版商:IEE    

年代:1990

数据来源: IET

摘要:

An accurate and soundly based representation of the complex stochastic processes encountered with optical preamplification in direct detection receivers is obtained. The objective of this study is the identification of a comprehensive moment generating function (MGF) characterisation for practical optically preamplified receivers. To effect this we build on a skeleton abstract formulation outlined some time ago with only limited physical and structural interpretation by Personick. Here we develop a MGF for the postdetection noise processes which takes into account a comprehensive set of key amplifier and receiver parameters, including gain and spontaneous noise characteristics of the semiconductor laser amplifier (SLA), amplifier facet reflectivity, bandwidth of the associated optical filter and postdetection electrical receiver filter characteristics. This comprehensive MGF may be used to obtain, via an independent route, the simple mean and variance characterisation of Yamamoto. We demonstrate this correspondence on a term-by-term basis and identify also minor discrepancies in two terms of the Yamamoto noise representation. The importance of the new MGF formulation is that it provides, for the first time, a sound formal basis which may be adopted for receiver design and analysis; this will enable, in any given situation, the adequacy or otherwise of a simple Gaussian approximation to be assessed.

DOI:10.1049/ip-j.1990.0068

出版商:IEE    

年代:1990

数据来源: IET