Magneto-Optical Properties of InSb for Infrared Spectral Filtering

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.