C-band high-power (519 mW CW/ 750 mW quasi-CW), low-noise distributed feedback semiconductor laser diode

A C-band high-power, low-noise distributed feedback (DFB) laser is demonstrated. The epitaxial structure incorporates a high-refractive-index layer in the N-doped region to improve single-transverse-mode characteristics and reduce intrinsic loss, enabling single-mode operation at a ridge width of 5 µm with an intrinsic loss of 2 cm^-1. At a test temperature of 15 °C, the DFB laser with a cavity length of 3.5 mm delivered an output power of 750 mW in quasi-continuous-wave mode and 519 mW in continuous-wave mode, with a side mode suppression ratio over 60 dB. The device also exhibits a minimum intrinsic linewidth of 14.9 kHz and relative intensity noise of -166 dBc/Hz.