It was shown some time ago that the space-time and the space-frequency degrees of polarization of a stochastic electromagnetic beam are not equivalent to each other. It is not possible, in general, to obtain a formal relationship between them. In this Letter, we discuss certain conditions under which they are directly related. These conditions lead to the concept of polarization-purity. If an optical beam obeys these conditions, its space-frequency degree of polarization has the same value at all frequencies present in the spectrum, and the value is equal to the space-time degree of polarization.
© 2013 Optical Society of America
Original Manuscript: December 20, 2012
Manuscript Accepted: December 27, 2012
Published: March 12, 2013
Mayukh Lahiri, "Concept of purity in the theory of optical polarization," Opt. Lett. 38, 866-868 (2013)