Optical heterodyne millimeter-wave generation using 1.55-mu m traveling-wave photodetectors

Optical heterodyne millimeter-wave generation using traveling-wave photodet ectors (TW-PDs) is examined both experimentally and theoretically. Ultrahig h-frequency InP-based 1.55-mum TW-PDs were fabricated and employed in an ex perimental setup for optical heterodyning. For the first time, optical hete rodyne millimeter-wave generation in excess of 160 GHz is experimentally de monstrated in frequency domain. The maximum electrical power delivered by t he TW-PD to a 5052 impedance is -11.5 dBm at 110 GHz with a polarization pe nalty of only 1.3 dB. Furthermore, a theoretical analysis in frequency doma in is presented describing the frequency response of TW-PD including effect s of the photogenerated carrier dynamics as well as optical and electrical wave propagation phenomena. A broad-band and flat frequency response is fou nd indicating a total rolloff of about 13.1 dB for a frequency span from 25 GHz to 200 GHz. Finally, the detectors responsivity is theoretically inves tigated to differentiate between the physical phenomena associated with hig h-frequency limitations.