Abstract
We have reviewed the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses using cascaded four-wave mixing (CFWM) in transparent bulk media, mainly concentrating on our recent work. Theoretical analysis and calculations based on the phase-matching condition could explain well the process semi-quantitatively. The experimental studies showed: (1) as many as fifteen spectral up-shifted and two spectral down-shifted sidebands were obtained simultaneously with spectral bandwidth broader than 1.8 octaves from near ultraviolet (360 nm) to near infrared (1.2 μm); (2) the obtained sidebands were spatially separated well and had extremely high beam quality with M2 factor better than 1.1; (3) the wavelengths of the generated multicolor sidebands could be conveniently tuned by changing the crossing angle or simply replacing with different media; (4) as short as 15-fs negatively chirped or nearly transform limited 20-fs multicolored femtosecond pulses were obtained when one of the two input beams was negatively chirped and the other was positively chirped; (5) the pulse energy of the sideband can reach a μJ level with power stability better than 1% RMS; (6) broadband two-dimensional (2-D) multicolored arrays with more than ten periodic columns and more than ten rows were generated in a sapphire plate; (7) the obtained sidebands could be simultaneously spectra broadened and power amplified in another bulk medium by using cross-phase modulation (XPM) in conjunction with four-wave optical parametric amplification (FOPA). The characterization showed that this is interesting and the CFWM sidebands generated by this novel method have good enough qualities in terms of power stability, beam quality, and temporal features suited to various experiments such as ultrafast multicolor time-resolved spectroscopy and multicolor-excitation nonlinear microscopy.
Highlights
Ultrafast time-resolved spectroscopy is a powerful technique for the investigation of electronic and vibrational dynamics in molecules, which are key elements in various fields in physics, chemistry, biology, and materials science research [1,2,3,4,5,6,7], mainly because this research can provide important information of electronic relaxation and dynamics in molecular vibrations [1,2,3,4,5,6,7]
We review our recent research progress on the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses by using cascaded four-wave mixing (CFWM) in transparent bulk media [30,31,32,33,34,35,46,50]
As a result, when the two input beams are focused into a nonlinear medium to generate CFWM sidebands, the leading edges of the up-shifted anti-Stokes sidebands (AS1) will have shorter wavelengths, while the down-shifted Stokes sidebands (S1) will have longer wavelengths
Summary
Ultrafast time-resolved spectroscopy is a powerful technique for the investigation of electronic and vibrational dynamics in molecules, which are key elements in various fields in physics, chemistry, biology, and materials science research [1,2,3,4,5,6,7], mainly because this research can provide important information of electronic relaxation and dynamics in molecular vibrations [1,2,3,4,5,6,7]. We review our recent research progress on the generation and amplification of wavelength-tunable multicolored femtosecond laser pulses by using CFWM in transparent bulk media [30,31,32,33,34,35,46,50].
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