Patent ID: 6268954
Filing Date: 2001-07-31
Classification: G02B,G02F,H01S

Abstract:
An optical circuit for gain tilt control of an amplifier and coupled thereto, the optical circuit comprising:a variable slope optical filter for in-line use with an optical amplifier signal, the filter being disposed upstream, downstream, or within the optical amplifier, the filter having a wavelength response that is sloped within a band of operation wavelengths of the amplifier, the slope of the filter within said band of wavelengths being between zero and one of a positive and negitive number, the filter for passing a band of wavelengths having a centre wavelength .lambda.c and having an amplitude response that has an opposite and counter slope as a function of wavelength to that of the amplifier's gain tilt within the operation band of wavelengths, the filter havinga port for receiving polarized light;means for providing a relative polarization difference between two predetermined wavelengths within the band of wavelengths and for controllably varying the polarization difference between the two wavelengths which includes a wavelength dependent element for providing the relative polarization difference between two wavelengths of an incoming beam in a controlled manner; anda polarizer for allowing a predetermined polarizations of light to pass therethrough and for substantially preventing and/or attenuating other predetermined polarizations of light to pass therethrough.