Nonlinear Wave Propagation in Cubic-Quintic Fiber Bragg Grating
Shubhada Kumbhaj, Santosh Pawar, Pratima Sen and Pranay Kumar Sen
Using nonlinear coupled mode equations the propagation of optical beam through fiber Bragg grating has been studied analytically taking into account the cubic-quintic nonlinear effects. Expression for the reflectivity of fiber Bragg grating is obtained considering the propagation of a quasi-CW laser beam at high input intensity. It is noticed that the quintic nonlinearity arising due to fifth-order optical susceptibility modifies the photonic band gap of Bragg grating and makes it transparent for entire band under high excitation intensity. From stability analysis, we find that the wave becomes unstable due to self phase modulation over a certain range of the detuning parameter.
Keywords: Cubic-quintic nonlinearity, fiber Bragg grating, self phase modulation, modulation instability, nonlinear refraction.