High-speed wavelength-swept semiconductor laser with a polygon-scanner-based wavelength filter

Ultrahigh-speed tuning of an extended-cavity semiconductor laser is demonstrated. The laser resonator comprises a unidirectional fiber-optic ring, a semiconductor optical amplifier as the gain medium, and a novel scanning filter based on a polygonal scanner. Variable tuning rates up to $1150 \mathrm{nm}/\mathrm{ms}$ (15.7-kHz repetition frequency) are demonstrated over a 70-nm wavelength span centered at $1.32 \mathit{\mu }\mathrm{m}$. This tuning rate is more than an order of magnitude faster than previously demonstrated and is facilitated in part by self-frequency shifting in the semiconductor optical amplifier. The instantaneous linewidth of the source is $<0.1 \mathrm{nm}$ for 9-mW cw output power and a low spontaneous-emission background of $-80 \mathrm{dB}$.