ANALYSIS OF A HOMODYNE RECEIVER USING AN INJECTION-LOCKED SEMICONDUCTOR-LASER

The purpose of this paper is to study an optical homodyne receiver using an injection-locked semiconductor laser as a local oscillator. The carrier recovery process introduces a phase error and the calculation of its statistical properties leads to the evaluation of the receiver performance. The analysis shows the dependence of the receiver performance on the injected power and the phase detuning between the transmitter and local oscillator electric fields. The receiver performance is affected by both the phase noises of the transmitter and local oscillators as well as by the shot noise of the detectors in the receiver and the modulation noise resulting from the injection locking of the local oscillator by a modulated signal. Within a linear analysis, the receiver sensitivity is shown to be improved by 1.6 dB in comparison with the balanced phase-locked loop for linewidths below 1 MHz. In the case when the overlap of the power spectral density of the message coding and the local oscillator filtering response is very small, the laser linewidth DELTA-omega-(rads-1) can be as high as 37 square-root 1/T(s), where T(s) is the bit duration in second, the BER is 10(-10) and the power penalty is 2.4 dB versus ideal detection.