Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer by High-Intensity Optical Subcarrier Signal

We experimentally investigate the effect of high-intensity subcarrier signal input to the UTC-PD-integrated HEMT working for optical-to-wireless carrier frequency down-conversion on enhancement of its double-mixing conversion gain. The fabricated UTC-PD-integrated HEMT demonstrated the linear increase in the conversion gain by up to +7 dB with increasing the subcarrier signal intensity without saturation, and the conversion gain enhancement of +6.8 dB from -51.0 dB to -44.2 dB was achieved.