Patent ID: 7149428
Filing Date: 2006-12-12
Classification: H04B

Abstract:
1. An apparatus for monitoring optical signal to noise ratio (OSNR) of wavelength division multiplexed optical signals having center wavelengths of λ 1 , . . . ,λ i , . . . ,λ n , (i=1,2, . . . ,n) in a wavelength division multiplexing optical transmission system, comprising: a polarization controller for controlling polarization states of the wavelength division multiplexed optical signals; a tunable optical bandpass filter for varying its center wavelength λ an optical signal separating means for separating the filtered optical signal into a first optical signal and a second optical signal; a linear polarizer for linearly polarizing the second optical signal; and an OSNR measuring means for obtaining, wherein the power of the second optical signal passing through the linear polarizer is minimized when a polarization state of the second optical signal is orthogonal to the polarization state of the linear polarizer and the powers of P