Long‐wavelength (λ ≥ 1.3 µm) InGaAlAs–InP vertical‐cavity surface‐emitting lasers for applications in optical communication and sensing

Abstract In this paper we present an overview of the properties and applications of long‐wavelength vertical‐cavity surface‐emitting lasers (VCSELs) based on the InGaAlAs–InP material system. With respect to significant temperature sensitivity of active material gain as well as insufficient thermal conductivity of InP‐based epitaxial compound layers, the effective thermal heat management appears as a major issue for application suitable device performance. In this context, the incorporation of a buried tunnel junction (BTJ) in connection with improved heat sinking resembles a breakthrough for long‐wavelength VCSELs. With the utilization of n‐type spreading layers and consequently ultralow series resistances, BTJ‐VCSELs exhibit sharply reduced excess heat generation. Furthermore, the BTJ‐approach enables self‐aligned optical and current confinement. A hybrid dielectric stack with Au‐coating yields an improved thermal heatsinking. The current status of BTJ‐VCSELs encompasses a number of superior performance values. At 1.55 µm wavelength, this includes room temperature single‐ and multimode continuous wave (cw) output powers of more than 3 mW and 10 mW, respectively, laser operation for heat sink temperatures well exceeding 100 °C, and optical data transmission rates up to 10 Gbit/s. The versatility of compound layer composition enables arbitrary emission wavelengths within a broad range of 1.3 and 2 µm. With respect to sensing applications, BTJ‐VCSELs appear as ideal components for optical detection of infrared active gases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)