Patent ID: 8160443

Claim:
A method for deriving an optical signal-to-noise ratio (OSNR) calibration factor ζ for an optical signal channel having an equivalent bandwidth of Δf eq comprising: inputting the optical signal channel into an optical spectrum analyzer and measuring a calibrated OSNR cal for the optical signal channel; inputting the optical signal channel into an interferometer comprising: adjusting a time delay τ of the interferometer to a first delay τ 1 , wherein the first delay τ 1 is zero; measuring an intensity A cal , at τ 1 ; adjusting the interferometer time delay τ to a second delay τ 2 , wherein the second delay τ 2 is much greater than the reciprocal of the optical signal channel's equivalent bandwidth Δf eq ; measuring an intensity B cal at τ 2 ; and calculating the calibration factor ζ known OSNR using the calibrated OSNR cal and the intensities A cal and B cal wherein the calibration factor ζ known OSNR equals B c ⁢ ⁢ al A c ⁢ ⁢ al × [ 1 + Δ ⁢ ⁢ f eq 12.5 ⁢ ⁢ GHz × 10 - ( OSNR c ⁢ ⁢ al 10 ) ] .