Estimation for Parameters of Semiconductor Lasers Using Self-mixing Effects in Semiconductor Lasers

摘要

The paper presents a new approach for estimating the linewidth enhancement factor (LEF) α of semiconductor lasers (SL) and the optical feedback level factor C in SLs. The proposed approach is based on the optical feedback self-mixing effects. This is a new technique in which a small fraction of the laser beam backscattered by a target is re-entering the laser active cavity, resulting in the modulation of both the amplitude and the frequency of the lasing field. We use a well-known self-mixing model on a laser diode operating at a weak feedback region, to best fit the observed self-mixing signal. The data fitting algorithm is based on the nonlinear least squares method. The effectiveness and accuracy of this method has been confirmed by computer simulation. It is shown that this algorithm is not affected by initial values if only chosen within the range of parameters. The estimation errors can be smaller than 4.8% for LEF and 1.4 for C when the SNR of signal is higher than 15 dB.