Convolutional Neural Networks (CNNs) are widely used due to their effectiveness in various AI applications such as object recognition, speech processing, etc., where the multiply-And-Accumulate (MAC) operation contributes to ∼ 95% of the computation time. From the hardware implementation perspective, the performance of current CMOS-based MAC accelerators is limited mainly due to their von-Neumann architecture and corresponding limited memory bandwidth. In this way, silicon photonics has been recently explored as a promising solution for accelerator design to improve the speed and power-efficiency of the designs as opposed to electronic memristive crossbars. In this work, we briefly study recent silicon photonics accelerators and take initial steps to develop an open-source and adaptive crossbar architecture simulator for that. Keeping the original functionality of the MNSIM tool , we add a new photonic mode that utilizes the pre-existing algorithm to work with a photonic Phase Change Memory (pPCM) based crossbar structure. With inputs from the CNN's topology, the accelerator configuration, and experimentally-benchmarked data, the presented simulator can report the optimal crossbar size, the number of crossbars needed, and the estimation of total area, power, and latency.