Strained-Layer InGaAs-GaAs-AIGaAs Buried-Heterostructure Lasers with Nonabsorbing Mirrors by Selective-Area MOCVD

Optical absorption in the active region near the facets of semiconductor lasers during high-power operation may result in catastrophic optical damage (COD). Several schemes to increase the COD limited optical power have been reported. One scheme entails forming non-injection regions near the facets to reduce the nonradiative recombination at the facets [1], [2]. A disadvantage of this scheme is that the non-injection region acts as a saturable absorber which may effect the L-I curve near threshold. Another scheme to increase the output power at which COD occurs involves forming a region at the laser facets which has a higher band gap energy than the energy of the emitted laser light. One method to produce these nonabsorbing mirrors (NAMs) utilizes bent-waveguides fabricated using nonplanar substrates [3], [4]. Although this method produces NAMs with broad near-fields, the coupling of the optical field between the window region and the light-emitting region is low due to the optical beam diffracting freely in the window region. In addition, accurate cleaving is necessary to achieve the relatively short window regions needed (<15 µm). Another method to produce NAMs uses an etch and regrowth technique, but this method also allows the optical beam to diffract freely in the window region and accurate cleaving is again needed [5].