Narrow-Linewidth Semiconductor Laser With High-Order Sidewall Gratings

We demonstrate a kind of ridge waveguide semiconductor laser with high-order sidewall gratings around 1550 nm. The ridge waveguide with 11th-order sidewall gratings is fabricated by the standard contact-types $i$ -line lithography. The fabricated device shows an output power of 44 mW at a bias current of 500 mA and a stable single-mode operation over wide ranges of current and temperature conditions. A high side-mode suppression ratio ( $\sim 59$ dB), a narrow linewidth of 63 kHz and a low relative intensity noise ( $ < -150$ dB/Hz under the frequency range from 0.03 to 20 GHz) have been demonstrated at $25^{\circ }\text{C}$ .