  We report on the design and characterization of a low-temperature external
cavity diode laser (ECDL) system for broad wavelength tuning. The performance
achieved with multiple diode models addresses the scarcity of commercial red
laser diodes below 633 nm, which is a wavelength range relevant to spectroscopy
of many molecules and ions. Using a combination of multiple-stage
thermoelectric cooling and water cooling, the operating temperature of a laser
diode is lowered to -64{\deg}C, more than 85{\deg}C below the ambient
temperature. The laser system integrates temperature and diffraction grating
feedback tunability for coarse and fine wavelength adjustments, respectively.
For two different diode models, single-mode operation was achieved with 38 mW
output power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below their
ambient temperature free-running wavelengths. The ECDL design can be used for
diodes of any available wavelength, allowing individual diodes to be tuned
continuously over tens of nanometers and extending the wavelength coverage of
commercial laser diodes.
