Giant tunable Faraday effect in a semiconductor magneto-plasma for broadband terahertz polarization optics

Takashi Arikawa,Junichiro Kono,Xiangfeng Wang,Alexey A Belyanin

doi:10.1364/oe.20.019484

Abstract

We report on a giant Faraday effect in an electron plasma in n-InSb probed via polarization-resolved terahertz (THz) time-domain spectroscopy. Polarization rotation angles and ellipticities reach as large as π/2 and 1, respectively, over a wide frequency range (0.3-2.5 THz) at magnetic fields of a few Tesla. The experimental results together with theoretical simulations show its promising ability to construct broadband and tunable THz polarization optics, such as a circular polarizer, half-wave plate, and polarization modulators.

Highlights

Recent advancements in terahertz (THz) technology [1] – for generation [2,3], manipulation [4,5], and detection [6] of electromagnetic radiation in the 0.1-10 THz frequency range – have enabled an impressive array of basic studies [7] and applications [8] in spectroscopy, imaging, security screening, and high-speed communications
We demonstrate a novel broadband and tunable THz polarization optics based on a giant Faraday effect in electron-doped InSb crystals
The magneto-optical properties of InSb have been studied for decades [20,24,26,27], but broadband Faraday rotation spectroscopy measurements have not been reported

Summary

Introduction

Recent advancements in terahertz (THz) technology [1] – for generation [2,3], manipulation [4,5], and detection [6] of electromagnetic radiation in the 0.1-10 THz frequency range – have enabled an impressive array of basic studies [7] and applications [8] in spectroscopy, imaging, security screening, and high-speed communications. One poorly developed area is active THz polarization optics, which would allow fast polarization modulations for e.g., real-time ellipsometric imaging [9,10] and vibrational circular dichroism of biological molecules [11,12]. Recent studies have proposed novel schemes based on artificial dielectrics and metamaterials for realizing THz quarterwave plates [13,14]. They exhibit excellent performances at a single frequency, suitable for narrowband or continuous-wave applications. There are a few previous reports on the generation of THz pulses with arbitrary elliptical polarization [16,17,18], which allow polarization modulations by mechanically changing the time delay between two optical pulses. A broadband polarization modulator between right- and left-circularly polarized modes has been demonstrated by utilizing a four-contact photoconductive antenna and linear-to-circular-polarization converter [19]

Results

Discussion

Conclusion