UTC-PD-Integrated HEMT for Optical-to-MMW/THz Carrier Frequency Down-Conversion: Scaling Rule of Conversion Gain on UTC-PD Mesa Size

We experimentally investigate the scaling rule of the conversion gain on UTC-PD mesa size of the UTC-PD-integrated HEMT for optical to MMW/THz frequency down-conversion. We showed that the conversion gain monotonically increases as the mesa size is reduced, due to the suppression of the in-plane diffusion of photogenerated electrons in the absorption layer.