Spectrum of the intensity of modulated noisy light after propagation in dispersive fiber

The spectral density of the optical intensity which results after modulated , noisy Light is propagated in dispersive single-mode fiber is investigated theoretically and experimentally, An exact general result is obtained for the case of lowest-order-only group velocity dispersion and is applied to l ight from a 1550-nm distributed-feedback semiconductor laser which is large -signal phase modulated and then propagated through 50 km of standard singl e-mode fiber, Experimental results demonstrate the effect of dispersion on the intensity spectrum (and thus, on Lightwave system characteristics such as modulation response, relative intensity noise, carrier-to-noise ratio, a nd harmonic distortion) in this situation and provide confirmation of the t heoretical results.