Generation of broadband two-dimensional multicolored arrays in a sapphire plate

Abstract

Broadband 2-D multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate using two crossed femtosecond laser beams overlapping in time and space. These multicolored 2-D arrays were sensitive to rotation of the sapphire plate in the plane normal to the incident beams. The broadband spectrum, pulse duration less than 40fs, and less than 1%RMS power stability of the array signals make them well suited for various applications, for example multicolor pump-probe experiments.

Tunable Multicolored Femtosecond Pulse Generation Using Cascaded Four-Wave Mixing in Bulk Materials

“…The phase-matching condition of CFWM has also been discussed and used to explain the generation of multicolored sidebands with two noncollinear pump laser pulses [60]. Our experiment has shown that more than 15 spectral upshifted sidebands and two spectral downshifted pulses can be obtained with a spectral width broader than 1.8 octaves, covering the range from UV to near-IR [55][56][57]59,60]. The spectra of the multicolored sidebands can also be tuned in the broadband spectral range by adjusting the cross-angle of the two pump beams or simply by replacing the nonlinear media [59,60].…”

“…Recently, four-wave mixing (FWM) has been studied as new method for the generation of ultrashort pulses, including few-cycle pulses, with a spectral range from deep-UV (DUV) to mid-IR [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]. Among these results, the multicolored laser pulses that can be generated using cascaded four-wave mixing (CFWM) in transparent bulk materials are particularly attractive, due to their ultra-broadband spectral range, large wavelength tunable range and compact configurations [54][55][56][57][58][59][60][61][62][63][64][65][66].…”

“…Among these results, the multicolored laser pulses that can be generated using cascaded four-wave mixing (CFWM) in transparent bulk materials are particularly attractive, due to their ultra-broadband spectral range, large wavelength tunable range and compact configurations [54][55][56][57][58][59][60][61][62][63][64][65][66]. Multicolored laser pulses generated by CFWM were first shown in semiconductor lasers in the 1980s [67].…”

“…In 2000, Crespo and his co-workers reported multicolored (>11 color) sideband generation using a cascaded highly nondegenerate FWM process in common glass [54]. Since then, studies have been conducted using other materials, such as sapphire plate [55,56], BBO crystal [57,58], fused silica glass [59], CaF2 [60], BK7 glass [60], and diamond [61,62]. These studies have carefully investigated the mechanism and characteristics of multicolored laser pulses.…”

“…The spectra of the multicolored sidebands can also be tuned in the broadband spectral range by adjusting the cross-angle of the two pump beams or simply by replacing the nonlinear media [59,60]. The pulse duration of different sidebands can be shorter than 50 fs without any extra dispersion compensation components [55][56][57]59,60], and sub-20 fs pulses can be obtained when the pump pulse chirp is carefully optimized [63]. Weigand and his co-workers also tried to recombine and synthesize all of the sidebands, and found that few-cycle visible-UV pulses were feasible [64,65].…”