Multimode-Oscillating Behavior in Index-Guiding V-Channeled Substrate Inner Stripe Lasers Depending on Structural Factor

Longitudinal-mode behavior in v-channeled substrate inner stripe (VSIS) lasers is presented. The lasing starts on multimodes and stabilizes on a single longitudinal mode with increasing current of more than a few percent above the threshold. Thus, the intrinsic spectral noise intensity shows two peaks at and slightly above the threshold. These characteristics are considered to result from the unique structure of VSIS lasers with small built-in refractive-index difference and narrow current channel.