Design of an Ultra-short Pulse Multicolor Distributed Feedback Dye Laser
This paper reviews critically the pulse shortening mechanisms of nanosecond to zeptosecond lasers and reports successful operation of multicolor distributed feedback dye laser. To demonstrate multicolor tunable ultrashort pulse generation a dye solution of Rhodamine 6G in ethanol may be pumped by four pairs of amplitude phase divided or wavefront divided second harmonic of a passively Q.switched or Q.switched and mode-locked Nd:YAG laser. The picosecond pump pulses, through coherence effects and resonant Bragg scattering, generate subpicosecond tunable multicolor laser lines. The number of laser lines increased linearly by increasing the pump laser pulses and reducing the mutual delays among the pump pulses. Normal interferences of two pulses at dye cell produces one laser line but pumping by multiple pump pulses produces a contemporary discrete supercontinuum of ultrashort laser pulses. Streak camera measurement shows that the number of laser lines vary from nine to thirteen for three to four pairs of pump pulses. The pulse lengths vary from 10 ps down to some unknown femtoseconds that could not be assessed accurately because of the 5ps measurement resolution limitation of the Imacon 674 Streak Camera. Experimental results on time delayed ultrashort pulses interference in dye cell have lead to the possibility of 13-color simultaneous attosecond pulses generation through autocorrelation of several closely spaced concurrent pulses from a distributed feedback dye laser.