A novel analytical expression of sensitivity to external optical feedback for DFB semiconductor lasers

A novel analytical formulation for expressing the effects of external optical feedback on the sensitivity of distributed feedback (DFB) laser structures is presented.The formulation is derived by presenting the pertinent laser parameters, such as the refractive index and waveguide loss, in terms of their average values. The resulting equation is then solved to obtain the numerical expression for the sensitivity coefficient. The expression reveals that the laser sensitivity is directly proportional to the ratio of the output power with the electromagnetic field intensity.