Influence of Substrate Material on Radiation Characteristics of THz Photoconductive Emitters

Figure 1

Operation principle of photoconductive antennas. The laser beam is focused on the dipole gap, the dipole gap, generating electron-hole pairs, and the transient current conditioned by the applied voltage emits an electromagnetic pulse of subpicosecond duration—the THz pulse—into the free space. The emitted wavelengths are much longer compared to the size of their source, the dipole; hence, they diffract strongly in the form of a wide cone filling out almost the whole solid angle behind the antenna (dark grey area marked THz).