Ali Moftakharzadeh - Department of Electrical Engineering, Yazd University, Yazd, Iran, Postal Code ۸۹۱۹۵-۷۴۱.
Behnaz Afkhami Aghda - Pishgaman Asr Ertebatat Company, Yazd, Iran.
Mehdi Hosseini - Department of physics, Shiraz University of Technology, Shiraz, Iran, Postal Code ۳۱۳-۷۱۵۵۵.

In this paper, the noise equivalent power (NEP) of an optical sensor based ongraphene-superconductor junctions in the constant current mode of operation has beencalculated. Furthermore, the necessary investigations to optimize the device noise withrespect to various parameters such as the operating temperature, magnetic field, deviceresistance, voltage and current bias have been presented. By simultaneously solving thefree energy and charge carrier density equations of graphene at low temperature, thespecific heat, thermal interaction of electron-phonon and current responsivity of thesensor have been calculated. Using these parameters, the noise equivalent power of thedevice has been obtained. The results show that the behavior of device NEP byincreasing the magnetic field at a constant temperature is at first ascending and thendescending. The NEP value for different temperatures, up to T=۸۰K, has an increasingbehavior and then by further increasing the temperature, the NEP will show decreasingbehavior which is also dependent on the value of the magnetic field. The NEP value isdirectly related to the device voltage and current values, therefore by increasing thevoltage and current, the NEP will increase. Our investigations show that at the constantcurrent bias mode of operation, the final device NEP is independent of the deviceresistance.

Graphene, Noise Equivalent Power (NEP), Optical Sensors, Superconductor