Controlling Actively Q-switched Laser Output by Nonlinear State Feedback

Q-switched lasers are prevalent in applications that require high intensity laser in ultra short pulses. For many medical applications of Q-switched lasers, it is crucial to have smooth and controlled pulse shapes [1, 2]. In dermatological applications, for instance, an irregular shape or duration of a laser pulse during pigmentation removal can cause serious damage to the surrounding healthy tissues [2]. In optical communication applications it is essential to produce reliable and clean pulse shapes. Q-switched fiber lasers are ideal candidates for optical signal generations for optical communication since light is already coupled into the fiber. However when fiber lasers are Q-switched, one often obtains complicated pulse shapes with multiple peaks. Thus, precise regulation of the output pulse shape would be a truly enabling technology for the application of fiber lasers in optical communications.