Abstract-Vertical versus planar pulsed photoconductive antennas that emit in the terahertz regime

E. Moreno, R. Sohrabi, G. Klochok, E.A. Michael

https://www.sciencedirect.com/science/article/pii/S0030402618304340

The design process of a photoconductive antenna (PCA), which emits efficiently in the electromagnetic terahertz range, demands some considerations that are discussed through this work. In this work, several essential characteristics of a photoconductive antenna made with LT-GaAS are studied by means of well established commercial software (COMSOL 5.3 [1]). An approach to the efficiency is also made through the study of geometry, the laser illumination position, the substrate doping distribution, the direction of the bias applied to the semiconductor, the matching impedance at the laser operating frequency and, finally, the plasmonics effects or penetration laser enhancement due to the use of nano antennas. We study and compare two kinds of structures, one which is quasi-bidimensional or planar and the other which is vertical. Additionally, the photoconductive antennas are also modeled by using a simplified equivalent circuit which helps to understand the antennas’ performance. Therefore some fundamental parameters, like the transient capacitance between the metal contacts are also studied. Furthermore, we introduce an optimized vertical design which achieves the best results.

Abstract-Time-domain numerical modeling of terahertz receivers based on photoconductive antennas

E. Moreno, Z. Hemmat, J. B. Roldán, M. F. Pantoja, A. R. Bretones, and S. G. García
https://www.osapublishing.org/josab/abstract.cfm?uri=josab-32-10-2034

We present here a simulator that solves the main semiconductor charge and transport equations coupled to Maxwell equations to study receivers based on photoconductive antennas (R-PCAs). Making use of this tool we were able to correctly characterize the operation of these antennas. In doing so, we compared simulations with the results of the semi-empirical expression 𝐼THz(𝑡)∝𝜎𝑐(𝑡)*𝐸THz(𝑡) employed to evaluate the detected photocurrent by means of the convolution between the photoconductivity in the receiver and the electric field linked to the emitter antenna. We were able to accurately reproduce experimental data with our simulation tool. These kinds of tools are essential to model photoconductive antennas, a fundamental step needed for the development of terahertz time-domain spectroscopy applications based on PCAs.

© 2015 Optical Society of America

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Abstract-On the Numerical Modeling of Terahertz Photoconductive Antennas

E. Moreno, M. F. Pantoja, F. G. Ruiz, J. B. Roldán, S. G. García

http://link.springer.com/article/10.1007%2Fs10762-014-0060-5

This paper shows the relevance of mobility models to describe the carrier dynamics for the analysis of radiative semiconductor photoconductive devices in the terahertz regime. We have built a simulator that self-consistently solves the device physics and Maxwell’s equations to study the radiated fields. In particular, we show a significant influence of an accurate description of the steady-state regime of the semiconductor device for calculating radiated electromagnetic fields in the broadside direction. Comparison with measurements shows the accuracy of our simulator and demonstrates the superior performance of numerical schemes based not only on the description of the carrier, electric potential, and field distributions, but also on reliable local mobility models.

Abstract-On the Numerical Modeling of Terahertz Photoconductive Antennas

• E. Moreno, 
• M. F. Pantoja, 
• F. G. Ruiz, 
• J. B. Roldán, 
• S. G. García

http://link.springer.com/article/10.1007%2Fs10762-014-0060-5

This paper shows the relevance of mobility models to describe the carrier dynamics for the analysis of radiative semiconductor photoconductive devices in the terahertz regime. We have built a simulator that self-consistently solves the device physics and Maxwell’s equations to study the radiated fields. In particular, we show a significant influence of an accurate description of the steady-state regime of the semiconductor device for calculating radiated electromagnetic fields in the broadside direction. Comparison with measurements shows the accuracy of our simulator and demonstrates the superior performance of numerical schemes based not only on the description of the carrier, electric potential, and field distributions, but also on reliable local mobility models.