GENERATION AND PHYSICAL-PROPERTIES OF A NEW FORM OF UNPOLARIZED LIGHT

We start from our recent analysis of unpolarized light [J. Lehner et a l., Phys. Rev. A 53 (1996) 2727] in which we distinguished two forms o f unpolarized light, dependent on whether the field is invariant with respect to phase retardation (type I) or not (type II). First we show that optical mixing leaves the type unchanged. Our main objective is t o devise a feasible experimental scheme for the generation of a new fo rm of unpolarized light. Specifically, we point out that amplitude-sta bilized unpolarized light is readily obtained with the help of two ind ependently operated lasers. However, this light is of type II only, an d we show that after passing a phase retarder it is no longer unpolari zed, according to our general criteria. Experimentally, this becomes o bvious from the fact that intensity fluctuations in a linear-polarizat ion mode vary with the polarization direction.