Transverse-mode stabilized Ga(1-x)Al(x)As visible diode lasers

Transverse-mode stabilized visible diode lasers in the 0.7-microm wavelength region are fabricated by growing a Ga(1-x)Al(x)As double heterostructure on a grooved GaAs substrate (channeled-substrate-planar structure). The diodes operate stably in the fundamental transverse mode and provide nonstigmatic laser beams. They can be collimated with a 0.5-1-mrad beam divergence using a simple graded-index fiber lens. Corresponding to single-longitudinal-mode operation at current levels above 1.1 times the threshold, a coherence length as long as 14 m is obtained in Michelson interference experiments.