Controlling the unstable emission of a semiconductor laser subject to conventional optical feedback with a filtered feedback branch

Our purpose in this work is to prevent periodic or chaotic oscillations in a semiconductor laser subject to conventional optical feedback (COF) by stabilizing it in a CW regime. We propose the use of a filtered optical feedback (FOF) from an external mirror in one of the external branches. Using FOF rather than COF the control of the system is easier and more effective. The proposed device consists of a semiconductor laser coupled to the two external reflectors. One branch is the conventional feedback branch (CFB) and the other is the filtered feedback branch (FFB). The frequency dependent reflectivity in the FFB is described by a Lorenzian function. The analytical solutions of the stationary states that are given by rotating wave solutions are presented.