Abstract

The asymmetric response of a gyrotropic medium to left and right circularly polarized light, as manifested in specular reflection, provides (1) a sensitive test of the electrodynamics of chiral media and (2) a novel spectroscopic method particularly suitable for nontransparent chiral materials in microquanitites. The differential reflection of circularly polarized light, d = (I_L-I_R)/(I_L+I_R) (where I_L and I_R is the reflected-light flux of specialized polarizations), is ordinarily linearly proportional to the chiral parameter(s) and is of the order 10⁵-10^-6 for many materials. However, for total reflection near critical angle, d is a nonlinear function of the chiral parameter(s) and can exceed the above range by several orders of magnitude.¹ This enhancement can be further increased by multiple reflection. For N passes at the critical angle from a weakly absorbing chiral sample, d is approximately N times greater than for a single pass. The enhancement factor is smaller than N to the extent that the incident angle departs from critical angle or N exceeds an optimal value. For sufficiently high N, the angular range of enhancement becomes too narrow to be of practical utility.

© 1990 Optical Society of America