| 摘要 |
In a terahertz radiation emitter a bias is applied between two contact assemblies (fig 1: 12, 13, 14) facing one another and separated by photoconducting semiconductor material (fig 1: 11). Transient currents excited by sub-picosecond laser pulses cause emission of radiation over a band dependent on the photoconductor cater lifetime. A step-up transformer is disposed between an ac bias supply 91 and the emitter 94. A resistive element (fig 1:14) may be integrated on the photoconductive substrate to restrict current flow between the contacts at frequencies lower than the desired emitting range, decreasing power dissipation of the device. The contacts can form a simple dipole antenna or a bow-tie antenna, edges of the elements adjacent the photoconducting gap comprising antenna electrodes. In some embodiments a dielectric film is disposed over the surface of the device (figs 2 and 3) filling the gap between antenna electrodes to suppress electrical breakdown. Other embodiments provide methods of determining an optimal resistive value for use as a series biasing resistance in a terhertz emitter, based on laser repetition frequency and device capacitance. |
