Stable single-longitudinal-mode operation in visible (AlGa)As semiconductor lasers coupled with a short external cavity

High stability of single longitudinal mode has been achieved in visible wavelength regions using V‐channeled substrate inner‐stripe lasers coupled with a short external cavity. The temperature dependence of the coupled‐gain peak coincided entirely with that of one longitudinal mode for lasers with external‐cavity lengths of 50–60 μm. As a result, a wide longitudinal‐mode locking range of 31 °C was obtained over 8 mW. This result is in good agreement with the theoretical calculation, in which the effect of the thermal expansion of the external‐cavity length is taken into account.