Study of mode locking process and time tailoring of short pulses
Marathe, Shreehari G.
Doctor of Philosophy
In this thesis, the analysis of mode locking process is formulated in terms of an eigenequation for the pulse envelope. The solutions of the eigenequation are found to be an infinite, denumerable set of supermodes, consisting of Hermite polynomials modulated by a Guassian envelope. The kinetics of pulse evolution from spontaneous noise is discussed in close analogy with the quantum statistical description. With the understanding of mode locked pulses, a new method to time tailor short pulses is presented. The method consists of the realization of a recursive filter by means of a suitable combination of high quality mirrors of different reflectivities. An algorithm to design a recursive filter for transforming a given pulse into a desired pulse is presented. As an example, a three mirror filter is designed to tailor a Guassian pulse to a pulse required for efficient laser induced controlled thermonuclear fusion.