An Efficient Photomixer Based Slot Fed Terahertz Dielectric Resonator Antenna.

Xiaohang Li,Salam Khamas,Wenfei Yin

doi:10.3390/s21030876

Xiaohang Li, Salam Khamas + Show 1 more

Open Access

https://doi.org/10.3390/s21030876

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Abstract

A slot fed terahertz dielectric resonator antenna driven by an optimized photomixer is proposed, and the interaction of the laser and photomixer is studied. It is demonstrated that in a continuous wave terahertz photomixing scheme, the generated THz power is proportional to the 4th power of the surface electric field of photocondutive layer. Consequently, the optical to THz conversion efficiency of the proposed photomixer has an enhancement factor of 487. This is due to the fact that the surface electric field of the proposed photomixer with a 2D-Photonic Crystal (PhC) superstrate has been improved from 2.1 to 9.9 V/m, which represents a substantial improvement. Moreover, the electrically thick Gallium-Arsenide (GaAs) supporting substrate of the device has been truncated to create a dielectric resonator antenna (DRA) that offers a typical radiation efficiency of more than 90%. By employing a traditional coplanar strip (CPS) biasing network, the matching efficiency has been improved to 24.4%. Therefore, the total efficiency has been considerably improved due to the enhancements in the laser-to-THz conversion, as well as radiation and matching efficiencies. Further, the antenna gain has been improved to 9dBi at the presence of GaAs superstrate. Numerical comparisons show that the proposed antenna can achieve a high gain with relatively smaller dimensions compared with traditional THz antenna with Si lens.

Highlights

Since the intensity is proportional to the square of electric field, the generated THz power is proportional to the 4th power of the electric field at the surface of LT-GaAs
The generated THz power is proportional to the 4th power of the electric field, the corresponding enhancement factor of the generated THz power is 487
The input impedance of the dielectric resonator antenna (DRA) with and without coplanar strip (CPS) network has been studied as shown in Figure 9, where it can be noted that the input resistance has been improved from 430 to 700 Ω by utilizing the CPS, which corresponding to an enhancement of matching efficiency from 15.8 to 24.5%

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Most of the THz systems that utilize time domain techniques employs bulky and expensive femtosecond lasers In this case, the optical excitation from the lasers can generate and detect sub-picosecond electrical pulses. It has been demonstrated earlier that an enhancement factor of 4 in the optical to THz conversion efficiency can be achieved by using plasmonic material as interdigital electrodes [22]. The optical to THz conversion efficiency of the photomixer has been optimized based on a numerical study and the utilization of a two-dimensional photonic crystal optical frequency selective surface (FSS) superstrate. GaAs substrate, in this case, the low temperature grown GaAs, LT-GaAs, to reduce the size of the antenna configuration and enhances the radiation efficiency. The simulations have been conducted using computer simulation technology (CST) microwave studio

Photomixer Design

Derivation of the Generated THz Power from the Photomixer

Photomixer Modeling

Antenna Configuration

Results and Discussion

Conclusions