High energy polarization of pulsars-observations vs. models

We review selected polarimetric observations of five pulsars in the optical energy range. Additionally, the UV/X-ray range observations are included for the Crab pulsar and its nebula. We compare the available theoretical results obtained in the framework of different models with the observed polarization characteristics of pulsar emission. In particular, we present new, high precision optical measurements of the Crab pulsar with time resolution of 10 mus. The high photon statistics allows us to identify the fine features in the phase dependencies of polarization degree (P.D.) and position angle (P.A.) of linear polarization never resolved before. The phase-resolved optical polarization characteristics show surprising correlations with the phase structure at radio frequencies. This subtle connection between presumed coherent and non-coherent emission, which have also been detected between the giant radio pulses and the optical intensity of the Crab pulsar [1], calls for more elaborate theoretical models than those currently available.