Knowledge Bank

Faraday rotation and Voigt double refraction experiments in the infrared have yielded information about the conduction band structure of III-V compounds. The measurements were carried out in the wavelength range 1$0-40\mu$. Polyethylene polarizers were used to produce and measure plane polarized light in the Faraday effect. Polyethylene polarizers and a quarter wave plate were used to measure elliptically polarized light in the Voigt effect. Either experiment gives the effective mass from a knowledge of wavelength $\lambda$, magnetic field H, dielectric constant $ϵ$;, and rotation angle $\theta$ or phase angle $\delta$ if the carrier concentration N is known. Combining the results of the two experiments gives both the effective mass and carrier concentration directly.