Effect of Linewidth Enhancement Factor on Fringe in a Self-Mixing Signal and Improved Estimation of Feedback Factor in Laser Diode

Effect of Linewidth Enhancement Factor on Fringe in a Self-Mixing Signal and Improved Estimation of Feedback Factor in Laser Diode

Blog Article

The optical output power of a laser diode is modulated by the self-mixing effect when the optical beam is back-reflected or back-scattered into the laser cavity by a target.The optical feedback factor C is the most important one that defines the feature of the self-mixing signals (SMSs).And the estimation Tips of C is indispensable for the displacement reconstruction by the phase unwrapping method because it is impossible to reconstruct the displacement with sub-wavelength resolution, provided the exact value of C is unknown.Unfortunately, C is subject to constant change during the measurement and, what is worse; its estimation is Fan Speed Resistor usually very time-consuming.

This paper studies the feature of a high and low fringe of SMSs in moderate and strong feedback regime and the effect of the feedback factor and the linewidth enhancement factor on the fringes and presents a simple approach to the estimation of C when C > 1.5 based on the behavioral model proposed by Plantier et al.In particular, the novel approach enables fast direct estimation of C because it is based on analytic relations between C and the amplitudes of the high and low peak in SMSs.