An improved method and apparatus for the measurement of the polarization
of light uses nonlinear polarimetry. The higher order moments of the E
field are measured and then transformed into standard polarimetry
parameters yielding the polarization of the light. In a first embodiment,
the light to be measured is transmitted through a rotating retarder. The
retarder is optically coupled to a fixed analyzer and light is then
detected by linear and nonlinear photodetectors. The spectra from the
detectors is calculated and transformed, to obtain the polarization. In a
second embodiment, the light to be measured is received by an optical
fiber comprising a plurality of fiber birefringences to retard the light.
Polarization sensitive gratings along the length of the fiber scatter the
light, and photodetectors detect the scattered light. Apparatus in two
preferred embodiments can perform the inventive method.