Interference with a frequency-modulated semiconductor laser

Theoretical and experimental studies of interference with a semiconductor laser whose frequency is directly modulated by the injection current are described. Theoretical expressions for the DC component and first harmonic contained in the interference signal are derived. It is shown that they can be used for estimating the frequency deviation of a modulated laser and for demodulating the interference signal, respectively. The influence of intensity modulation caused by direct modulation is also considered. Experiments were carried out using Michelson and polarization interferometers illuminated by directly modulated AlGaAs semiconductor lasers.<
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