Tunable external-cavity semiconductor laser using monolithically integrated tapered amplifier and grating coupler for collimation

A novel lensless tunable external-cavity laser using monolithically integrated tapered amplifier, grating coupler (GC) and an external half mirror is proposed and demonstrated. It can be fabricated by a simple process and emits a collimated output beam. By making use of wavelength dispersion of the GC, the lasing wavelength can be angle tuned. Wavelength tuning over a wide range of 21.5 nm by 4.5/spl deg/ device rotation and an 84-mW output power were achieved under continuous-wave operation. A well-collimated output beam with a divergence angle as small as 0.3/spl deg/ was maintained over the entire tuning range.