Vertical cavity surface emitting laser with monitoring diode

摘要

A vertical cavity surface emitting laser (VCSEL) and monitoring diode combination has reduced parasitic capacitance for use in high bandwidth communications systems. The VCSEL 20 has both p-type and n-type contacts 24,26 on the same face. This allows the VCSEL to be mounted on the photo-detecting surface of a monitor chip or diode 10 without using a metal contact layer. In an embodiment wherein the VCSEL is soldered to the monitor chip for mechanical stability only a small metal pad no larger than the VCSEL is used. The reduction in metallisation results in a lower parasitic capacitance that in turn results in higher potential operational speeds. The VCSEL and diode are mounted in a package having a window or lens with a partially reflective surface such that some light emitted by the VCSEL is reflected back to the monitoring diode. The VCSEL may be top or bottom emitting.