Photonic High-Power 160-GHz Signal Generation by Using Ultrafast Photodiode and a High-Repetition-Rate Femtosecond Optical Pulse Train Generator

Abstract

We demonstrate photonic high-power MMW generation at subTHz (160 GHz) frequencies by using ultrafast near-ballistic unitraveling carrier photodiodes (NBUTC-PD), which have a miniaturized active area (24 μm ² ) and flip-chip bonding package for good heat-sinking. Under optical sinusoidal signal excitation with a ~85% modulation depth, 165-GHz optical-to-electrical 3-dB bandwidth, 18-mA saturation current, +5.11-dBm maximum output power at 160-GHz operating frequency has been demonstrated. In order to further mitigate device-heating, we developed a high-power pulsed optical signal source with increased optical modulation depth: a femtosecond optical short-pulse generator with extremely high repetition rate (160 GHz) and pulsewidth as short as 285 fs. With this novel source, we generated high MMW power (+7.8 dBm) with an effective 120% optical modulation depth at 160 GHz directly from the NBUTC-PD.