MULTIPLE-FREQUENCY GENERATION OF SUB-TERAHERTZ RADIATION BY MULTIMODELD EXCITATION OF PHOTOCONDUCTIVE ANTENNA

Multiple-frequency coherent radiation in the sub-terahertz region was generated by excitation of a photoconductive antenna with a commercial ly available multimode laser diode (LD), The origin of the radiation w as the current modulations in the photoconductive antenna caused by th e optical beats between the longitudinal modes of the LD. An interfero metric spectral measurement showed line spectra at frequency multiples of 52 GHz beyond 400 GHz, This result indicates that the photoconduct ive antenna with a multimode LD excitation can achieve a wavelength-se lectable coherent radiation source in the sub-terahertz region with a very simple and compact device configuration.