Characterization of chaotic emission of a laser diode in optical feedback conditions produced by different external reflectors

The external-cavity semiconductor laser (ECSL) system is obtained when the radiation emitted by a semiconductor laser is redirected into the laser cavity as feedback from an external reflecting surface. In the present work, we experimentally evaluated the chaotic dynamics of the laser diode emission at the low-frequency fluctuation (LFF) regime using different external optical reflectors in the ECSL system. The stability of the LFF regime was analyzed using the same function parameters of the ECSL system and considering selective and unselective external reflectors with respect to the wavelength. We show that a stable LFF regime is obtained for selective reflector with single-mode emission; for selective and unselective with multimode emission, but at higher laser power if compared with the single-mode case. Unstable LFF regimes were obtained for multimode laser emission using selective or unselective reflector at laser power levels similar to single-mode laser emission case.