A new external-cavity diode laser system based on an extended version of the Littman configuration is investigated. In our laser system the tuning mirror is replaced with a second grating mounted at the Littrow angle. This double-grating design provides a smaller passive bandwidth than the grating-mirror configuration, which is used to compensate for the large angle-of-incidence-dependent losses of the grazing-incidence grating. This results in a broader continuous tuning range with an improved mode stability. Because two laser diodes, emitting at 820 and 775 nm, respectively, are used, the external-cavity laser is continuously tunable without mode hops across 35 nm at 820 nm and 27 nm at 775 nm. Such a laser was used to measure the absorption lines of the oxygen A band around 762 nm. The complete R - and P -rotational branches of the b ∑g1 +(ν′′=0)←X 3∑g-(ν ′=0) transition were recorded in a single-wavelength scan.
© 1997 Optical Society of America
D. Wandt, M. Laschek, A. Tünnermann, and H. Welling, "Continuously tunable external-cavity diode laser with a double-grating arrangement," Opt. Lett. 22, 390-392 (1997)