Numerical investigation of saturation behaviors in photoconductive antennas under high bias conditions

Ramin Emadi; Zaker Hossein Firouzeh; Reza Safian; Abolghasem Zeidaabadi Nezhad

doi:10.1117/1.OE.58.2.027112

15 February 2019 Numerical investigation of saturation behaviors in photoconductive antennas under high bias conditions

Ramin Emadi, Zaker Hossein Firouzeh, Reza Safian, Abolghasem Zeidaabadi Nezhad

Author Affiliations +

Optical Engineering, Vol. 58, Issue 2, 027112 (February 2019). https://doi.org/10.1117/1.OE.58.2.027112

Abstract

A photoconductive antenna (PCA) is modeled using a higher order solution derived from the Boltzmann’s equation to accurately predict anomalous behaviors in this system. In the case concerning the application of high bias fields, photoexcited carriers gain sufficient energies, so that they become hot carriers. Moreover, screening fields in PCAs are numerically investigated in the first picoseconds subsequent to the excitation using hot-carriers effects. To explore another exotic phenomenon in a PCA, its driving photocurrent is decomposed into DC and THz components. Then, the saturation behavior of the THz component peak and the sublinear dependence of the DC component with respect to an externally applied bias are numerically investigated. Furthermore, depending on the accumulation of photoexcited carriers, velocity overshoot phenomenon may occur in the driving photocurrent against the applied bias. These phenomena cannot be predicted by the conventional drift-diffusion model. To simplify the analysis of PCAs, a time-dependent equivalent circuit model is proposed for describing the associated operational principles. Finally, using a coherent detection scheme and the circuit model, it will be shown that owing to the screening fields, the THz power saturates with respect to the applied laser power.

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Ramin Emadi, Zaker Hossein Firouzeh, Reza Safian, and Abolghasem Zeidaabadi Nezhad "Numerical investigation of saturation behaviors in photoconductive antennas under high bias conditions," Optical Engineering 58(2), 027112 (15 February 2019). https://doi.org/10.1117/1.OE.58.2.027112

Received: 24 August 2018; Accepted: 4 February 2019; Published: 15 February 2019

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