Pulse Compression Photoconductive Switching Using Negative Differential Mobility

• Published in: IEEE transactions on electron devices Vol. 69; no. 2; pp. 590 - 596
• Main Authors: Dowling, Karen, Dong, Yicong, Hall, David, Mukherjee, Saptarshi, Schneider, Joseph D., Hau-Riege, Stefan, Harrison, Sara E., Leos, Laura, Conway, Adam, Rakheja, Shaloo, Voss, Lars
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Anodes; Apertures; Arsenides; Communications systems; Coplanar waveguides; Electric fields; Gallium; Gallium arsenide; Gallium–arsenide (GaAs); Illumination; Lasers; negative differential mobility (NDM); Optical communication; Optical pulse compression; Optical switches; Optoelectronic devices; photoconductive switch; Pulse compression; Pulse duration; Radio frequency; Satellite communications
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2021.3136500

This work demonstrates a novel optoelectronic device with the potential for use as a high-frequency, high-power RF source or amplifier. The device is a gallium-arsenide coplanar waveguide with a small gap in the signal trace for optical illumination. A confined charge cloud is generated by illumination through an aperture in an opaque mask over this gap. An electric field above the threshold for negative differential mobility (NDM) enables pulse compression, which prevents the charge cloud from spreading temporally during the drift process. Due to the NDM phenomenon, the output electrical pulse is temporally compressed compared to the input optical pulse. This phenomenon is demonstrated using three different experiments with varied laser pulsewidth (28-700 ps) and device geometry (50- and 100-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>-length gaps). A 66% reduction in the full-width at half-maximum of the electrical pulse relative to the input optical pulse was demonstrated. This novel coupled optoelectronic device opens avenues for high-frequency, high-power, compact devices that could enable next-generation satellite communication systems with faster data rates and longer ranges.