A photo-controlled, all-solid, and frequency-tunable ultra-wideband pulse generator

Abstract

With the continuous exploration of the bioelectric effect, nanosecond and picosecond pulsed electric fields used in cancer therapy and drug introduction have attracted great attention. In this paper, an ultrashort pulsed electric field generator is proposed, which connects two photoconductive semiconductor switches in parallel to generate unipolar and bipolar pulses. We described the experimental scheme of the generator and the simulation of the radio frequency combiner. A 532 nm laser with pulse widths of 1 ns and 500 ps is used to trigger the photoconductive semiconductor switches. The experimental results show that the scheme can achieve adjustments of 357 and 720 MHz for the center frequency and the 3 dB bandwidth, respectively. The results confirm that this proposed scheme can be used for unipolar/bipolar frequency-adjustable ultra-wideband pulse generation.

Characteristics Comparison of SiC and GaN Extrinsic Vertical Photoconductive Switches

“…Second, increasing carrier lifetime τ can increase photoelectric conversion efficiency. However, when the carrier lifetime is too long, it may affect the high-frequency response ability of the PCSS, resulting in longer tail of the output single pulse waveform and poorer modulation of the pulse cluster waveform [28]. The deep-level doping of semiconductor will help to achieve the semi-insulating characteristics of PCSS, but the carrier lifetime will decrease with the increase of doping, thus reducing the photoelectric conversion efficiency of photoconductive switches [29].…”