Conversion Gain Enhancement of a UTC-PD-Integrated HEMT Photonic Double-Mixer by High-Intensity Optical Subcarrier Signal. - Dai Nakajima; Kazuki Nishimura; Mitsuki Watanabe; Tsung-Tse Lin; Keisuke Kasai; Masato Yoshida; Tetsuya Suemitsu; Taiichi Otsuji; Akira Satou (OFC, 2023)