A $W$ -Band Photonic Transmitter/Mixer Based on High-Power Near-Ballistic Uni-Traveling-Carrier Photodiode (NBUTC-PD)

In this letter, we demonstrate a $W$-band photonic transmitter/mixer fabricated by the flip-chip bonding of a high-power back-illuminated near-ballistic uni-traveling-carrier photodiode (NBUTC-PD) and an end-fire quasi-Yagi antenna on an AlN substrate. This end-fire and directional antenna design eliminates the need for the integration of an additional Si-lens into the antenna for directional power transmission. The high bias dependent nonlinearity of the integrated NBUTC-PD means that the bias modulation technique can be used to directly up-convert the intermediate-frequency signal to a millimeter-wave signal at $W$ -band without using a costly high-speed optical modulator. A reasonable detected power ($-$ 17 dBm at 106 GHz) can be achieved with the demonstrated device with a high-output photocurrent (30 mA) and a low internal-conversion loss ($-$2.4 dB) between the radio-frequency and local-oscillator signals at $W$-band.