Pulse spreading in a single-mode optical fiber due to third-order dispersion: effect of optical source bandwidth

Pulse spreading in a single-mode optical fiber is discussed taking into account the third-order dispersion term of the waveguide when an optical source with a finite spectral width is modulated by a Gaussian-shaped pulse. Explicit forms for group velocity and pulse width are obtained taking into account both the optical source bandwidth and modulation bandwidth, and these are compared with those obtained by a simple theory. A condition is also made clear how small the second-order dispersion term has to be before the thirdorder dispersion term becomes important.