Abstract
In the region of the band edge of a degenerate n-type InSb sample, at fixed wavelength, oscillations in the absorption have been observed which are periodic in 1H. The period of these oscillations yields information about the Fermi surface. In the region of free carrier absorption oscillations in the absorption have been observed which are periodic in 1H, the period yielding the free carrier effective mass. The two measurements hold promise of an optical means of measuring both carrier concentration and effective mass of free carriers in semiconductors.