  A coherent optical spectrum analyzer is integrated with a rotating quarter
wave plate polarimeter. The combined polarimeter optical spectrum analyzer
(POSA) allows the extraction of the state of polarization with high spectral
resolution. POSA is used in this work to study two optical systems. The first
is an optical modulator based on a ferrimagnetic sphere resonator. POSA is
employed to explore the underlying magneto-optical mechanism responsible for
modulation sideband asymmetry. The second system under study is a cryogenic
fiber loop laser, which produces an unequally spaced optical comb. Polarization
measurements provide insights on the nonlinear processes responsible for comb
creation. Characterizations extracted from POSA data provide guidelines for
performance optimization of applications based on these systems under study.
