Abstract

RODE is a simple handedness-blind ellipsometer¹ that measures the ellipse of polarization of a totally polarized light beam or the first three Stokes parameters of partially polarized light. We constructed and operated a RODE using a single Si planar-diffused photodiode at the He-Ne laser wavelength of 632.8 nm. The detector surface, which has an oxide-layer coating of halfwave thickness, intercepts the incoming light beam at an ~70° angle of incidence (AOI). The output signal of the detector is recorded at equispaced, 5° apart, angular positions as it is rotated around the incident light beam as an axis. Fourier analysis (or least-squares fit) of this sampled signal determines the polarization parameters of incident light. The instrument is calibrated first to determine the modulation depth m_L for linearly polarized incident light and is tested subsequently with elliptically polarized light. RODE is found to determine with reasonable accuracy the azimuth and ellipticity of such light. An important source of error is the small fluctuation of the AOI as the detector is rotated. We found that this AOI sensitivity can be greatly reduced by proper choice of the oxide-layer thickness and incidence angle. For example, with a 514.2-nm film, m_L varies by ±0.1% when the AOI is changed from 73.4 to 79.0°.

© 1988 Optical Society of America