Robust and Wavelength Insensitive Performance of Selectively Oxidized Vertical-Cavity Lasers

Abstract

The unique properties of vertical-cavity surface emitting lasers (VCSELs), such as circular output beam, single longitudinal mode, and 2-dimensional array capability, make them promising light sources for a variety of applications, including optical data links, data storage, display and printing systems. Moreover, on-wafer testing and compatibility with traditional integrated circuit fabrication technologies make VCSEL manufacture feasible and potentially inexpensive. Recently, VCSELs fabricated using "wet" oxidation1 have demonstrated the lowest threshold current (91µA),2 lowest threshold voltage (45mV above photon gap),3 and highest power conversion efficiency (52%)4 ever reported in VCSELs. The latter two results were obtained from an all semiconductor VCSEL structure that utilizes selective oxidation to form buried oxide layers. The low index oxide layers form current apertures sandwiching the active region to efficiently confine injected carriers as well as transversely confine the emitted photons. In this paper we show that the fabrication uniformity we have obtained using our selective oxidation process can reproducibly yield high performance VCSELs that are attractive for potential applications. In addition, these lasers exhibit high performance over a wide emission wavelength range from a given wafer. Finally, our selectively oxidized device structure is demonstrated to be robust and amenable to a variety emission wavelengths, currently extending from the infra-red to visible.