Optical communication systems show promising results in terms of data transmission in the microwave and terahertz (THz) frequency range. Consequently, photonic integrated circuits (PICs) provide numerous advantages like high transfer rate, minimal loss for long distance communication, reduced power consumption, etc. Nonetheless, in such densely packed PICs, a large number of photonic components are tightly confined in a small space resulting in thermal crosstalk which eventually hampers the system performance. Deep trench supported designs can alleviate the thermal crosstalk in such systems to a large extent. Here, by simulations, we mitigate thermal crosstalk and enhance the performance in terms of Bit Error Rate and extinction ratio for an optical transmitter-receiver system with back-to-back and 5 km optical transmission line configuration at a high data rate with deep trench assisted silicon-based Mach-Zehnder modulator and a Si-Ge avalanche photodetector at the transmitter and receiver, respectively.