A Detailed Investigation of UTC Traveling Wave Photodetectors

Effects of the absorber's thickness on the UTC TWPD's performance are investigated. This is an important parameter because it affects both external efficiency and the bandwidth of the device. The analysis of the photodetectors is done using a hybrid drift-diffusion-TLM method, which takes into consideration both, carrier dynamics and RF propagation characteristics. To improve the external efficiency of the UTC TWPD, a thicker absorber is needed. However, a thicker absorber also reduces the transit bandwidth of the photodetector. It is found that the bandwidth of a high frequency UTC TWPD with a thick absorber can be improved by optimizing the length of the device