Patent ID: 7079320

Claim:
An optical communications device for selectively modifying a multiwavelength optical beam having a selected polarization with a given center wavelength and edge wavelengths, while compensating for nonlinearities at the edge wavelengths which affect data reliability, comprising: a voltage controlled liquid crystal cell functioning as an optical modulator receiving the optical beam and introducing a selectively controllable amount of retardation in the beam; and at least three retardation compensators in the path of the beam prior to the optical modulator, the at least three retardation compensators comprising at least one optical half wave quartz wave plate at the center wavelength, at least one nominally quarter wave plate that is identically equal to a quarter wave at the center wavelength and a third quartz plate of less than a tenth wave at the center wavelength to compensate for the residual cell birefringence, said optical wave plates providing integer multiples of retardation selected in relation to the center wavelength and edge wavelengths of the optical beam and a retardation characteristic of the optical modulator, each said wave plate having selected optical axis dispositions relative to the polarization axis of the optical beam.