Various types of high-voltage supplies: (a) dc pulsed, short unipolar voltage pulses are separated by the laser repetition rate; (b) ac pulsed, pulses alternate in polarity; and (c) ac sine wave, average voltage of zero and frequency of a half of the laser repetition rate.
Noise measured at the output of a detector amplifier with optical sampling pulse blocked. (a) Normally connected photoconductive emitter (vertically offset for clarity). (b) Photoconductive emitter disconnected from electrical circuit.
Bias voltage across the electrodes of a large-area photoconductive emitter: (a) normally connected (vertically offset for clarity) and (b) electrically disconnected.
Effect of blocking the conduction path with a mask. The reduction in signal is consistent with the reduction in illuminated area. (The ripple after the peak is due to absorption by atmospheric water vapor.)
Terahertz emission signal measured from optically induced charge transfer in betaine dissolved in chloroform.
Schematic of resonant sine wave supply (series and parallel connected). The monostable allows the voltage peak to be synchronized with the laser pulse. The parallel-connected circuit requires a dc-blocking capacitor which is chosen to be approximately ten times .
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