Journal of Physical Chemistry & Biophysics
Open Access

A Short Note on Ultrafast Laser Spectroscopy

Raviz Rina^{* *}Correspondence: Raviz Rina, Department of Physics, University of Babylon, Hilla, Iraq, Email:

Author info »

Description

Ultrafast laser spectroscopy is a spectroscopic strategy that involves ultrashort pulse lasers for the investigation of elements on extremely short time scales (attoseconds to nanoseconds). Various methods are utilized to examine the dynamics of charge carriers, atoms, and molecules. Various techniques have been developed spanning different time scales and photon energy ranges.

Titanium-sapphire lasers are tunable lasers that emit red and near infrared light (700 nm-1100 nm). Titanium-sapphire laser oscillators use titanium doped-sapphire crystals as an increase medium and Kerr-lens mode-locking to accomplish subpicosecond light pulses. For amplification, laser pulses from the titanium-sapphire oscillator should initially be extended in time to prevent damage to optics, and then are injected into the cavity of another laser where pulses are amplified at a lower repetition rate. Regeneratively amplified pulses can be additionally enhanced in a multi-pass amplifier. Following amplification, the pulses are recompressed to pulse widths same to the original pulse widths.

A dye laser is a four-level laser that involves a natural dye as the increase medium. Pumped by a laser with a fixed frequency, because of different dye types use, different dye lasers can discharge beams with various wavelengths. A ring laser design is most frequently utilized in a dye laser framework.

A fiber laser is normally created first from a laser diode. The laser diode then couples the light into a fiber where it will be restricted. Various frequencies can be accomplished with the utilization of doped fiber. The pump light from the laser diode will excite a state in the doped fiber which can then drop in energy causing a specific wavelength to be emitted.

Ultrafast optical pulses can be utilized to produce X-beam pulses in different ways. An optical pulse can excite an electron pulse through the photoelectric effect, and acceleration across a high potential gives the electrons kinetic energy. At the point when the electrons hit an objective, they create both characteristic Xrays and bremsstrahlung. A subsequent technique is by means of laser-induced plasma. When very high-intensity laser light is incident on a target, it takes electrons off the target making a negatively charged plasma cloud.

For accurate spectroscopic estimations to be made a several attributes of the laser pulse should be known; pulse duration, pulse energy, spectral phase, and spectral shape are among some of these. Data about pulse duration can be determined through autocorrelation measurements, or from cross-correlation with another well-characterized pulse. Techniques taking into account total characterization of pulses include Frequency-Resolved Optical Gating (FROG) and Spectral Phase Interferometry for Direct Electric-Field Reconstruction (SPIDER).

Pulse shaping is to alter the pulses from the source in a clear manner, including manipulation on pulse’s amplitude, phase, and duration. To amplify pulse’s intensity chirped pulse amplification is commonly applied, which includes a pulse stretcher, amplifier, and compressor. It won't change the span or period of the pulse during the amplification.

High Harmonic Generation (HHG) is the nonlinear cycle where intense laser radiation is changed from one fixed frequency to high harmonics of that frequency by ionization and recollision of an electron.

Different spectroscopy tests require different excitation or probe wavelengths. Hence, for this reason frequency conversion procedures are regularly used to expand the operational spectrum of existing laser light sources. The most widespread conversion methods rely on using crystals with second-order non-linearity to perform either parametric amplification or frequency mixing.