Shift lens external-cavity diode laser for broad wavelength tuning and switching

We propose an external-cavity laser diode that uses an electromagnetically actuated collimating lens for wavelength tuning. Because the wavelength in the grating equation is highly sensitive to the incident angle, a slight (approximately 1 microm) transverse displacement of the collimating lens induces a wavelength shift of approximately 1 nm. We experimentally demonstrate a single-mode, stable, reproducible, and cw tuning over a range of 8 nm. The wavelength is proportional to the current applied to the lens actuator, and no hysteresis is observed within the experimental error. By changing the current, we achieve fast and reproducible wavelength switching.