Analysis of optical matching in the photodiode module for CATV

An analysis of lightwave propagation in the photodiode module was developed to optimize its performance and balance the parameters such as the sensitivity and the back reflection required for cable TV application. The photodiode module is represented as a planar p-i-n photodiode chip placed into the fibre optic matching receptacle. The main goal is a theoretical study of the lightwave propagation through the optical fibre-matching medium-p-i-n photodiode chip system. It is shown that using the matching medium with the refractive index close to that of quartz gives possibility to exclude focusing elements and obtain a minimum of reflected surfaces. Utilization of the matching medium reduces angular divergence of the optical radiation from the fibre and reflection from the photodiode chip that results in an increase of photodiode module sensitivity.