Biphoton light with hidden polarization and its polarization tomography

Abstract

Polarization properties of biphoton light, emitted by an optical parametric oscillator, are studied both theoretically and experimentally. The theoretical treatment is performed using the Stokes operator formalism; polarization density matrix of the light fields; and the quasi-probability function, which represents an analog of the field Wigner function. The hidden polarization of biphoton light is demonstrated experimentally with the help of elements of polarization tomography.