Modeling and Evaluation of Cascaded Mach Zehnder Modulators for Multi-band Chirped Radar Signal Generation and IF Signal Detection

The cascaded configuration of Mach-Zehnder Modulators (MZMs) can generate multiple short optical pulses. This configuration can be used as an optical pulse source for various applications including radar systems. In this work, we are proposing a method in which these pulses are used as a radar reference signal that plays an important role in the generation of radar transmit signal and detection of Intermediate Frequency (IF) signals during reception. The repetition rate and number of frequency comb lines are controlled by adjusting the frequency of external input signal applied to the MZMs and the cascading stages. As per the operational frequency requirement of the radar system, the suitable comb components are selected to generate the required RF transmit signal. During receive operation, the same frequency comb component will be used for the detection of IF signal. This paper includes various results of cascaded MZM configuration with changes in RF input frequency, number of cascaded stages and its application results obtained during generation and detection processes. The work is supported with a mathematical analysis which is in compliance with modeling results. The same architecture is extended for the generation of multiband chirped RF signals with centre frequencies at 6.5 GHz (C-band) and 9.5 GHz (X-band) and for the retrieval of respective IF signals.