In this paper we report effect of optical illumination on Silicon MOSFET. The MOSFET has been studied in respect of current voltage, transconductance admittance and scattering parameters. Gain analysis of the Silicon MOSFET is done in dark and under optical illumination. The device is fabricated using ATHENA™ process simulator and the device simulation is performed using ATLAS™ from SILVACO international. The simulation results indicate potential of MOSFET as optically sensitive structure which can be used for increase in data transmission/reception rates, reduction of interconnect delays, elimination of clock skew, or as a photodetector for optoelectronic applications at low and radio frequency.