Detectors Based on a Resonant Cavity

Abstract

In the SOI chapter, rather inefficient resonant cavity detectors with quantum efficiencies up to 27% were described. Here, a different approach, which also is appropriate for Si detectors with a bandwidth of several GHz, for the improvement of the quantum efficiency will be introduced. The efficiency improvement of the detectors can be achieved by an enhancement of the reflection coefficients on the top and bottom of the Si device layer by implementation of so-called Bragg reflectors. In addition to the efficiency enhancement for selected wavelengths, the efficiency for other wavelengths is reduced to near zero by the implementation of the Bragg reflectors. An example of a resonant cavity enhanced Si detector with a quantum efficiency of 65 % at 700 nm, with an optical bandwidth of 20 nm, and with a bandwidth of up to 5 GHz will be discussed.