Continuously tunable external-cavity diode laser with a double-grating arrangement

Abstract

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 $b{ }^1{{\mathrm{\Sigma }}_g}^{+}({\nu }^{″}=0)\leftarrow X{ }^3{{\mathrm{\Sigma }}_g}^{-}({\nu }^{\prime }=0)$ transition were recorded in a single-wavelength scan.

© 1997 Optical Society of America

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