Asymmetric Cladding Ridge Waveguide Laser by Selective Area MOCVD

Abstract

Stable fundamental mode operation of a semiconductor laser is a requirement for nearly all laser applications and the method to achieve that goal is usually an index guided laser. Two common index guided laser structures are the buried heterostructure (BH) and the ridge waveguide (RW). Both of these structures have been shown to have stable fundamental mode operation to several times threshold [1-3]. Generally, BH lasers have more stable operation but RW lasers are simpler to fabricate. RW lasers are commonly fabricated by etching trenches into the top cladding layer to within a few tenths of a micron of the active region, thus reducing the effective index of the mode in the etched region. The index step for the waveguide is a strong function of the etch depth and precise control of the etch mechanism is necessary to provide an adequate amount of waveguiding without introducing unnecessary loss by etching too deep.