Long wavelength vertical cavity surface emitting laser with integrated photodetector

摘要

A vertical cavity surface emitting laser (VCSEL) integrated with a photodetector is provided. The photodetector is attached to a bottom surface of the VCSEL by a bonding layer, which includes a window of a predetermined diameter. The bonding layer is a eutectic bonding layer. An air gap exists within the window and mainly transmits a laser beam. Most of spontaneous emission light incident at an angle is blocked by an area of the bonding layer other than the window, and even some of the spontaneous emission light that heads toward the window cannot easily passes through the window due to a big difference between refractive indices of a semiconductor layer and the air. Thus, the eutectic bonding layer greatly reduces a voltage drop at an interface between the VCSEL and the photodetector, thereby contributing to mass production. <IMAGE>