Optical pulse ultrashort

Shank C V 1988 Generation of ultrashort optical pulses Ultrashort Laser Pulses and Applications ed W Kaiser (Berlin Springer) pp 5-34... 

To carry out a spectroscopy, that is the structural and dynamical determination, of elementary processes in real time at a molecular level necessitates the application of laser pulses with durations of tens, or at most hundreds, of femtoseconds to resolve in time the molecular motions. Sub-100 fs laser pulses were realised for the first time from a colliding-pulse mode-locked dye laser in the early 1980s at AT T Bell Laboratories by Shank and coworkers by 1987 these researchers had succeeded in producing record-breaking pulses as short as 6fs by optical pulse compression of the output of mode-locked dye laser. In the decade since 1987 there has only been a slight improvement in the minimum possible pulse width, but there have been truly major developments in the ease of generating and characterising ultrashort laser pulses. 

Meshulach, D., and Silberberg, Y. 1999. Coherent quantum control of multiphoton transitions by shaped ultrashort optical pulses. Phys. Rev. A 60 1287-92. 

The possibility of reflection of electrons by an evanescent wave formed upon the total internal reflection of femtosecond light pulses from a dielectric-vacuum interface is quite realistic. The duration of the reflected electron pulses may be as long as 100 fs. In the case of electrons reflecting from a curved evanescent wave, one can simultaneously control the duration of the reflected electron pulse and affect its focusing (Fig. lc). Of course, one can imagine many other schemes for controlling the motion of electrons, as is now the case with resonant laser radiation of moderate intensity [9, 10]. In other words, one can think of the possibility of developing femtosecond laser-induced electron optics. Such ultrashort electron pulses may possibly find application in studies into the molecular dynamics of chemical reactions [1,2]. 

Fig. 7.2 Two-beam experimental setup for femtosecond transient absorption studies using a white light continuum. A commercially available CPA 2101 laser system delivers the pulses. Ultrashort tunable visible pulses are obtained by the NOPA optical parametric converter. A chopper wheel is used to cut every second pump pulse in order to compare the signal with and without the pump. The white light continuum is generated by a sapphire disc. The time delay between the pump and probe pulses is adjusted by the optical delay rail...

Tanabe T, Ohno K, Okamoto T, Yamanaka M, Kannari F (2004) Feedback control for accurate shaping of ultrashort optical pulses prior to chirped pulse amplification. Jpn. J. Appl. Phys. 43 1366-1375... 

Fig. 8.3. Ultrashort optical pulses can be shaped by adjusting the phase and amplitude of each spectral component [27]. In the device, the input pulse is incident on a grating that disperses the different colors in different directions, as shown in the figure. The colors are collimated and focused by a lens or mirror. A second similar arrangement in reverse reconstitutes the pulse by redirecting the colors to another grating. At the mutual focal plane of the two lenses, the spectrum of the input pulse is completely resolved so that each spatial location corresponds to a single frequency (or a narrow band). By inserting at this plane a material that causes variations in the phase of each resolved frequency, one can construct a pulse of arbitrary shape, constrained only by the spatial resolution of the arrangement.

There are two different techniques that are used to measure the time profiles and optical oscillations of ultrashort pulses noncoUinear intensity correlation and interferometric autocorrelation. While the former measures the envelope of the pulse, the latter can even measure the optical oscillations within the pulse envelope. Combined with the spectral resolution, the time profiles of the different spectral components within the optical pulse spectrum can be simultaneously measured by the FROG technique. The relative phases of these spectral components are observable using the SPIDER technique (see Sect. 6.2.4). 

L.R Christov, Generation and propagation of ultrashort optical pulses, in Progress in Optics, vol. 24 (North Holland, Amsterdam, 1991), p. 201... 

C. laconis, LA. Walmsley, Spectral phase interferometry for direct electric-field reconstruction of ultrashort optical pulses. Opt. Lett. 23,792 (1998)... 

Frequency upconversion of 800 nm ultrashort 175 fs optical pulses by two-photon absorption in a stilbenoid compound-doped polymer (PMMA) optical fiber was reported [28]. By the intensity-dependent transmission method, the two-photon absorption cross section was deduced. The combination of a well-designed organic chromophore incorporated into a fiber geometry is appealing for the development of an upconversion blue polymer laser. Upconversion fluorescence and optical power limiting effects based on the two- and three-photon absorption process of a frans-4,4 bis(pyrrolidinyl)stilbene were investigated [29]. The molecular TPA cross section three-photon absorption (3PA) cross section g3 at 720-1000 nm were measured. The 3PA-induced optical power-limiting properties were also illustrated at 980 nm. 

For a more quantitative description and explanation of the fine structure beats we consider an excitation of Ns, atoms by ultrashort light pulses in a level system as shown in Fig. 1 for the ground and first excited state in Na. The width of the optical pulses may be so short that the impact excitation condition is satisfied. Then the fine structure during the excitation cannot be resolved. Within this time an atomic system can reasonably be represented by a fundamental scheme of eigenfunctions labeled by the quantum numbers L, S, m, and mg. 

Shimizu, T, Watanabe-Ezoe, Y., Yamaguchi, S., Tsukatani, H., Imasaka,T, Zaitsu, S., Uchimura,T, Imasaka,T. (2010) Enhancement of molecular ions in mass spectrometry using an ultrashort optical pulse in multiphoton ionization. Anal. Chem.,82,3441-3444. 

FIGURE 1 The geometry of the problem. Ultrashort optical pulse with the electric field E(AT,y, z, f) is directed along the tube axis x, moving in the transverse direction along the axisz. 

C. V. Shank, Generation of Ultrashort Optical Pulses in Ultrashort Laser Pulses and Applications, Vol. 60 Topics in Applied Physics, W. Kaiser (ed.) (Springer, Berlin, Heidelberg, 1988), p 5. 

Kane D J and Trebino R 1993 Single-shot measurement of the intensity and phase of an arbitrary ultrashort pulse by using frequency-resolved optical gating Opt. Lett. 18 823-5... 

Weber FIP (1967) Method for pulsewidth measurement of ultrashort light pulses generated by phase-locked lasers using nonlinear optics. J Appl Phys 38 2231-2234... 

With development of ultrashort pulsed lasers, coherently generated lattice dynamics was found, first as the periodic modulation in the transient grating signal from perylene in 1985 by De Silvestri and coworkers [1], Shortly later, similar modulation was observed in the reflectivity of Bi and Sb [2] and of GaAs [3], as well as in the transmissivity of YBCO [4] by different groups. Since then, the coherent optical phonon spectroscopy has been a simple and powerful tool to probe femtosecond lattice dynamics in a wide range of solid... 

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