The well-known problem of penetration through an internally reflecting barrier is treated as it relates to the extraction of a laser beam from an internally reflecting cavity. A quantity <i>d</i> log<i>T</i>/<i>d</i> log<i>n</i> which relates the fractional change of transmittance to the fractional change of refractive index is defined and is shown to be large for large barrier spacing. It is suggested that this strong dependence of transmittance on the value of <i>n</i> may be used in studying and controlling laser beams.
HAROLD A. DAW, "Investigation of Laser Modulation by Modifying the Internal Reflection Barrier," J. Opt. Soc. Am. 53, 915-915 (1963)