Spectral linewidth reduction in partly gain-coupled 1.55 μm strained multiple quantum-well distributed feedback laser

Abstract

The effective linewidth enhancement factor αeff and the spectral linewidth Δυ are reported for the first time for a partly gain-coupled distributed feedback laser with a gain corrugation in a strained multiple quantum-well active region emitting at 1.55 μm wavelength. The αeff value is estimated to be as low as 1 and is independent of the laser cavity length L, while a decrease in the linewidth-power product ΔυPo with L has been observed, with a measured linewidth of 2 MHz at 10 mW optical output power for 300-μm-long devices. The experimental results demonstrate that a small αeff is obtained due to the strain and the gain coupling effects, while further reduction of the spectral linewidth with L is the result of longitudinal index coupling effects.