Littrow configuration tunable external cavity diode laser with narrowband emission at 448 nm

Abstract

A single-mode external cavity diode laser (ECDL) emitting in the blue spectral region is developed. The ECDL, which uses a low-power Fabry-Perot laser diode, is designed in the Littrow configuration using a reflective holographic grating. The ECDL has a narrowband emission at 448 nm of 0.01 nm that coincides with a strong absorption cross-section of NO 2 gas molecule, tuning ranges of 4.0 nm just above the threshold and 0.2 nm at high injection current. A maximum output power of 60 mW and an efficiency of 80 % with respect to the Fabry-Perot laser diode in free-running condition are achieved. High stability of the laser system over many hours was also achieved with a fluctuation of less than 1 %.