A Littrow-type diode laser with independent control of cavity length and grating rotation

We present our patented extended-cavity diode laser (ECDL) based on a modified Littrow configuration. Here, the coarse wavelength adjustment via the rotation of a diffraction grating is decoupled from the fine tuning of the external cavity modes by positioning a piezoelectric transducer behind the diode laser. As a result, the fine adjustment of the laser frequency with the piezo does not affect neither the optical feedback alignment nor the broader grating frequency selection curve, resulting in a better mode-hop stable performance compared to the one of standard Littrow ECDLs without optimized pivotal point. We characterize the design and show that it is well suited to atomic and molecular experiments demanding a high level of stability over time and for long cavities ECDLs.