Narrow-Spectral-Linewidth Wavelength-Tunable Laser Diode with Si Wire Waveguide Ring Resonators

Abstract

We fabricated wavelength-tunable laser diodes with Si wire waveguide ring resonators as an external optical cavity. The footprint of the optical cavity including the semiconductor optical amplifier is as small as 2.73×0.89 mm2, which is about 1/5 of those made of silicon oxinitride material. About 44-nm-wavelength tuning operation, which covers the entire L-band of the optical communication wavelength range, was obtained. Furthermore, spectral linewidth narrower than 100 kHz was obtained by optimizing the design of the external optical cavity. The tunable laser diodes with narrow spectral linewidth are suitable as light sources for digital coherent optical transmission systems.