External cavity laser diode with 40 nm continuous tuning range around 825 nm

We report on a broadly tunable external cavity semiconductor laser near 825 nm employing a grating mounted in grazing incidence. The laser system is tunable without mode hops in the wavelength range from 800 nm to 840 nm with output powers up to 6.5 mW. For the first time, such an external cavity laser has been used to obtain the water vapor absorption spectrum in ambient air between 814 nm and 831 nm in a single scan.