Developments for Improved Performance Vertical-Cavity Surface Emitting Lasers

Sammanfattning: The vertical-cavity surface-emitting laser (VCSEL) is a type of laser diode that emits light from the surface of the chip from which it is manufactured rather than from a cleaved edge as so far has been common for most telecommunication lasers. VCSEL’s low cost, high power efficiency and low power consumption properties make it a very attractive signal source for many applications such as fiber optical communication, optical interconnects, 3D sensing, absorption spectroscopy, laser printing, etc.In this work, we have developed and evaluated new designs and technologies for extending the performance of VCSELs based on the GaAs material system. A novel scheme for single-mode emission from large size VCSELs, with active region size up to 10 ?m, is proposed and discussed. Oxide-free designs of the VCSEL structure either based on an epitaxially regrown p-n-p layer or a buried tunnel junction (BTJ) for lateral current confinement are fabricated and characterized; the latter scheme yielding significant dynamic and static performance improvement as compared to epitaxially regrown design. In addition, the first room-temperature operation of a heterojunction bipolar transistor (HBT) 980nm VCSEL, a so-called transistor-VCSEL, is demonstrated. This novel three-terminal operational VCSEL is believed to have the potential for a ultrahigh modulation bandwidth due to altered carrier dynamics in the cavity region.