Abstract

Optically pumped visible vertical-cavity surface-emitting lasers (VCSELs) composed of InAlGaP active regions and AlAs/Al_0.5Ga_0.5As distributed Bragg reflectors (DBRs) were recently demonstrated..¹ These structures take advantage of the growth refinements developed for the near infrared VCSELs by using AlGaAs DBRs. The primary disadvantages of the AlGaAs/InAlGaP approach include uncertainties in band line-ups and refractive index profiles at the As-P and P-As interfaces and difficulties with p-type doping transitions. An alternative approach is to replace the AiGaAs DBRs with an in(Al_xGa_1-x)P/In(Al_yGa_1-y)P quarter wave stack. Despite a smaller difference in refractive index (at 670 nm Δη/η = 8% for an In_0.5Al_0.5P/In_0.5(Al_0.2Ga_0.8)_0.5P DBR compared with Δn/n = 12% for an AlAs/Al_0.5Ga_0.5AS DBR), there are several potential advantages. The all-phosphide VCSEL has a lower overall Al content, which reduces device-processing complexity and improves reliability. Additionally, the lasing range of the all-phosphide VCSEL can be extended to shorter wavelengths than is possible with AlAs / AiGaAs DBRs because of the larger energy bandgaps. For example, a "green" high reflector with negligible absorption is possible at λ < 570 nm bv using an InAlP/In(Al_{0 5}Ga_D_₅)P DBR stack.⁵

© 1993 Optical Society of America