Infrared and Laser Engineering, Volume. 48, Issue 4, 402001(2019)
Terahertz radiation of a butterfly-shaped photoconductive antenna(invited)
The terahertz(THz) far-field radiation properties of a butterfly-shaped photoconductive antenna (PCA) were experimentally studied using a home-built THz time-domain spectroscopy(THz-TDS) setup. To distinguish the contribution of in-gap photocurrent and antenna structure to far-field radiation, polarization-dependent THz field was measured and quantified as the illuminating laser beam moved along the bias field within the gap region of electrodes. The result suggests that, although the far-field THz radiation originates from the in-gap photocurrent, the antenna structure of butterfly-shaped PCA dominates the overall THz radiation. In addition, to explore the impact of photoconductive material, radiation properties of butterfly-shaped PCAs fabricated on both low-temperature-grown GaAs(LT-GaAs) and semi-insulating GaAs(Si-GaAs) were characterized and compared. Consistent with previous experiments, it is observed that while Si-GaAs-based PCA can emit higher THz field than LT-GaAs-based PCA at low laser power, it would saturate more severely as laser power increased and eventually be surpassed by LT-GaAs-based PCA. Beyond that, it is found the severe saturation effect of Si-GaAs was due to the longer carrier lifetime and higher carrier mobility, which was confirmed by the numerical simulation.
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Jitao Zhang, Mingguang Tuo, Min Liang, Wei-Ren Ng, Michael E. Gehm, Hao Xin. Terahertz radiation of a butterfly-shaped photoconductive antenna(invited)[J]. Infrared and Laser Engineering, 2019, 48(4): 402001
Received: Nov. 14, 2018
Accepted: Dec. 28, 2018
Published Online: Jul. 23, 2019
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