GaAs-(AlGa)As large optical cavity lasers

Some principles behind the construction and operation of GaAs-(AlGa)As large optical cavity (LOC) lasers are discussed. An LOC laser is made by adding a waveguide region near the active region in a DH laser four-layer structure. The thickness of the waveguide region is approximately 0.5 to 3.0 microns. Both the active region and the waveguide region constitute the output waveguide region of the device. A liquid phase epitaxial method is used to fabricate the laser. On the basis of measurements of pulse output power, beam divergence, wavelength, and external differential quantum efficiency, it is found that the lasers will operate efficiently in the CW mode at room temperature if narrow stripe, improved heatsink, better bonding techniques, and suitable exciting current are used. Finally, LOC lasers can be more easily coupled to other devices because of their thicker output waveguide regions.