Optical Feedback Self-mixing Interferometry Research Articles

Linewidth enhancement factor measurement based on optical feedback self-mixing effect: a genetic algorithm approach

We present a data-to-model fitting approach to estimate the linewidth enhancement factor (LEF) of semiconductor lasers using optical feedback self-mixing interferometry (OFSMI) operating in the weak feedback regime. Existing data-to-model fitting techniques require a priori knowledge regarding target moving trajectory or displacement which restricts their applicability. This paper addresses this issue by proposing a genetic algorithm (GA) to estimate OFSMI system parameters including the LEF based on observed data without prior information. The performance of this method has been verified through both simulation and experimentation, which indicates an accuracy of 3.8% for the LEF measurement.

Toward Automatic Measurement of the Linewidth-Enhancement Factor Using Optical Feedback Self-Mixing Interferometry With Weak Optical Feedback

This paper proposes an approach for automatically measuring the linewidth-enhancement factor (LEF) of semiconductor lasers using optical feedback self-mixing interferometry (OFSMI), which works in weak optical feedback regime and where the external target is subject to simple harmonic vibration with unknown vibration frequency and magnitude. According to well-known Lang-Kobayashi theory the waveform of the modulated optical output power from the OFSMI system is influenced by multiple parameters, including the LEF, the optical feedback level factor, and the parameters related to the movement of external target. In order to estimate LEF, other parameters must also be considered and, hence, a multiple parameter estimation strategy is required. We propose a solution for this multiple parameter estimation problem based on the principle of data-to-theoretical model match. In particular, a strategy for minimizing a cost function in order to achieve the best fitting is proposed with which all the unknown parameters can be estimated. The performance of the proposed approach is tested using experimental data in comparison with other two approaches. It is seen that, over different experimental signals, the standard deviation for estimated LEF is less than 4.58% on average, which shows that results have excellent consistency. Moreover, the proposed approach also provides a solution for vibration measurement (that is, vibration frequency and magnitude).

Estimating the parameters of semiconductor lasers based on weak optical feedback self-mixing interferometry

The paper presents a practical approach for measuring the linewidth enhancement factor /spl alpha/ of semiconductor lasers and the optical feedback level factor C in a semiconductor laser with an external cavity. The proposed approach is based on the analysis of the signals observed in an optical feedback self-mixing interferometric system. The parameters /spl alpha/ and C are estimated using a gradient-based optimization algorithm that achieves best data-to-theoretical model match. The effectiveness and accuracy of the method has been confirmed and tested by computer simulations and experiments, which show that the proposed approach is able to estimate /spl alpha/ and C with an accuracy of 6.7% and 4.63%, respectively.