Continuous Tuning of a Diode Laser Over 8.4 THz Near 1550 nm With a Chirped Grating

We achieve mode-hop-free tuning of an extended-cavity diode laser with an original technique. The external coupler is a chirped (varied line-space) diffraction grating. A simple linear translation of the grating is then sufficient to obtain continuous tuning. The measured continuous tuning range has reached 66 nm (8.4 THz) near a wavelength of 1550 nm with a relatively constant output power of 3 mW.