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

We present a novel, to the best of our knowledge, extended-cavity diode laser based on modified Littrow configuration. The coarse wavelength adjustment via rotation diffraction grating is decoupled from fine tuning external cavity modes by positioning piezo transducer behind laser, making robust against misalignment and hysteresis even with long cavities. Two prototypes cavities different lengths were tested 780 nm diode, locked an atomic reference. observed mode-hop-free frequency tunability broader than free spectral range upon changes in its length. design well suited molecular experiments demanding high level stability over time.