Magneto-Optical Properties of InSb for Infrared Spectral Filtering

TL;DR

This paper investigates the Faraday effect in n-type InSb to evaluate its potential as a tunable infrared spectral filter, providing measurements of Verdet coefficient, absorption, and device prototypes.

Contribution

It introduces a comprehensive measurement of the Faraday effect in InSb across various carrier concentrations and demonstrates a prototype for a tunable infrared filter.

Findings

Verdet coefficient determined for different carrier concentrations

Absorption coefficients measured and figures of merit calculated

Preliminary results show feasibility of a tunable Faraday rotation filter

Abstract

We present measurements of the Faraday effect in n-type InSb. The Verdet coefficient was determined for a range of carrier concentrations near $10^{17}$ $\text{cm}^{-3}$ in the $\lambda$ = 8 $\mu$m - 12 $\mu$m long-wave infrared regime. The absorption coefficient was measured and a figure of merit calculated for each sample. From these measurements, we calculated the carrier effective mass and illustrate the variation of the figure of merit with wavelength. A method for creating a tunable bandpass filter via the Faraday rotation is discussed along with preliminary results from a prototype device.