Patent ID: 7171130

Claim:
An optical performance monitor for measuring the operating characteristics of an optical transmission signal, the optical performance monitor comprising a linear optical detector responsive to the optical transmission signal for measuring the power of said optical transmission signal; and a nonlinear optical detector responsive to said optical transmission signal for generating a substantially quadratic, nonlinear output signal S NL determining signal distortions associated with: (1) chromatic dispersion, using the relation: S NL =ηT 2 P ave 2 ·1/τ, where η is a proportionality constant associated with the nonlinear detector, T is defined as the bit period of the optical transmission signal, τ is defined as the pulse duration of the optical transmission signal, and P ave is the average pulse power, the value of τ being an indicator of the presence of chromatic dispersion; (2) polarization mode dispersion, using the relation: S NL =ηT 2 P ave 2 ·1 /τ[x 2 +(1 −x ) 2 ], where “x” is defined as the fractional amplitude of a first polarization state and (1−x) is defined as the fraction amplitude of a second, orthogonal polarization state; and (3) accumulated amplified spontaneous emission of said optical transmission signal using the relation: S NL =ηP ave 2 T[x 2 +( T /τ)(1 −x ) 2 ], where the term T/τ is indicative of the amount of accumulated amplified spontaneous emission.