Suppression of low frequency fluctuations in a laser diode subject to two optical feedbacks

We show, for the first time to our knowledge, that low frequency fluctuations (LFF) can be suppressed with a second adequate optical feedback. We suggest that LFF may be suppressed by shifting the maximum gain mode and its antimode away from the other external cavity modes or, better, by inducing the pair to disappear. Without modifying any parameter of the first optical feedback and laser diode, this can only be achieved by applying a second feedback. Moreover, we observe laser stabilization when the second optical feedback parameters are carefully chosen.