The main goal of this research is design of an ultraviolet photodetector based on intersubband transitions in III-Nitride multiple quantum well. Due to the abundance of visible light detectors, optically pumped lasers with ability of converting incident ultraviolet radiation to visible light are proposed. In this way, incident wavelength of about 352nm at ultraviolet wavelength band is converted to wavelength of 559nm at visible range using intersubband transitions in III-Nitride multiple quantum well structures.To calculate parameters of the structure, wave functions and energy levels are obtained by solving 1-D Schrodinger–Poisson equation self consistently at 300°K. Responsivity and optical gain for the designed structure are 4.623(mA/w) and 10.28 (1/cm) at 300°K respectively.