Abstract
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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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.
Highlights
P HOTOCONDUCTIVE semiconductor switches (PCSSs) have several advantages over other typical gated power transistors
Two device gap lengths were used in these experiments, 100 and 50 μm. We find that these dimensions yield a clear experimental signature of the presence of pulse compression in GaAs pulse compression photoconductive switch (PCPS), which is the main result of this article
These results clearly show that the extracted FWHM of the output pulses is narrower compared to the input laser PW, and the peak voltage of the output pulse increases as the dc electric field across the device is increased
Summary
P HOTOCONDUCTIVE semiconductor switches (PCSSs) have several advantages over other typical gated power transistors They can support extremely high voltages and conduct large currents with negligible carrier doping. This places a hard, material-defined limit on the upper frequency of operation of PCSS. To the best of our knowledge, this work is the first experimental demonstration of optoelectronic pulse compression with a confined charge cloud in an NDM material. This concept leads to a high-frequency and high-power RF device, which will enable future remote communication
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