The nanowire transistors on silicon-on-insulator (SOI) substrate embedded with ferroelectric hafnium-zirconium-oxide (HfZrO2) are elaborately probed when the devices are illuminated with the ultraviolet (UV) laser. The basic functionality of the ferroelectric nanowire transistor can be verified by monitoring the drain current hysteresis during the bidirectional gate voltage scan. Therefore, this study mainly analyzes and summarizes the electrical response of the device to ultraviolet (UV) irradiation; the main emphases will be placed on the rotational direction of the hysteresis window and the width of the hysteresis window when components of different dimensions are compared with one another. To administer the comparisons impartially, the pertinent surface-to-volume ratios of these nanowire transistors are used as the gauging parameters. As the device measurements would demonstrate, Hysteresis rotating in a clockwise direction is attributed to the oxide layer defects, while the counterclockwise direction is induced by the ferroelectric effect. Needless to say, the quality of the device itself is still contingent upon the gate oxide robustness and the quality of its adjacent interfaces. And last but not least, the threshold voltage shift is also used as an indicator to illuminate the impact of changing polarization effect on the nanoscale devices. Through the effective modulation of the hysteretic window by irradiating the nanowire FETs with a UV laser, we believe many unique applications involving the optical modulation and photodetection that are commonly found in silicon photonics can be realized.