A low-temperature external cavity diode laser for broad wavelength tuning

摘要

We report on the design and characterization of a low-temperature externalcavity diode laser (ECDL) system for broad wavelength tuning. The performanceachieved with multiple diode models addresses the scarcity of commercial redlaser diodes below 633 nm, which is a wavelength range relevant to spectroscopyof many molecules and ions. Using a combination of multiple-stagethermoelectric cooling and water cooling, the operating temperature of a laserdiode is lowered to -64{\deg}C, more than 85{\deg}C below the ambienttemperature. The laser system integrates temperature and diffraction gratingfeedback tunability for coarse and fine wavelength adjustments, respectively.For two different diode models, single-mode operation was achieved with 38 mWoutput power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below theirambient temperature free-running wavelengths. The ECDL design can be used fordiodes of any available wavelength, allowing individual diodes to be tunedcontinuously over tens of nanometers and extending the wavelength coverage ofcommercial laser diodes.