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 cm − 3 in the λ = 8– 12 μ m long-wave infrared regime. The absorption coefficient was measured and a figure of merit was calculated for each sample. From these measurements, we calculated the carrier effective mass and illustrated the variation of the figure of merit with the wavelength. A method for creating a tunable bandpass filter via the Faraday rotation is discussed along with preliminary results from a prototype device.