Direct Estimation of the Optical Feedback Factor C From the Amplitude of the Optical Feedback Interferometric Signal.

In this article, we combine the intrinsic properties of the optical feedback factor C with a precalibration technique to assess the value of C when the laser operates in and across the weak, moderate, and strong feedback regimes. The proposed technique directly estimates C via the amplitude of the optical feedback signal as a first approximation. It thus requires much less computing resources than existing algorithms. Experimental results show that an estimation of C with a precision better than <8.1% after calibration has been achieved. The performance repeatability has also been quantified by running the system over several days. Furthermore, continually time-varying C estimation has been achieved more efficiently than with previously reported techniques. This implies that it could be exploited for future real-time optical feedback interferometry (OFI) systems to retrieve target displacement more accurately, thereby potentially enabling operation from C extending from weak feedback to strong feedback.