Compact and Inexpensive Continuous-Wave Sub-THz Imaging System Using a Fiber-Coupled Multimode Laser Diode

We propose and demonstrate a sub-THz imaging system using a continuous-wave (CW) multimode laser diode (MLD). The sub-THz generation is achieved by photomixing between simultaneously oscillating longitudinal modes of the MLD on a photoconductive antenna (PA). The use of a fiber-coupled MLD makes the system compact and inexpensive. In the system both amplitude and phase information are obtained from the signals at only appropriate two points on the delay line.