Femtosecond laser pulse shaping by use of microsecond radio-frequency pulses

Hillegas, Curtis W.; Tull, J. X.; Goswami, Debabrata; Strickland, D.; Warren, W. S.

doi:10.1364/ol.19.000737

Cited by 272 publications

(125 citation statements)

References 8 publications

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“…First, a large coherent bandwidth is produced by an ultra-short pulse generation technique ¶ ¶ (59)(60)(61). Then, the spectrum is dispersed with a grating or a prism, and each frequency component is addressed individually by a spatial light modulator [a liquid crystal array (62,63) or an acoustic modulator (64)]. This way, individual spectral amplitudes and phases can be adjusted independently.…”

Section: Fast Carsmentioning

confidence: 99%

FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

212

139

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Airborne contaminants, e.g., bacterial spores, are usually analyzed by time-consuming microscopic, chemical, and biological assays. Current research into real-time laser spectroscopic detectors of such contaminants is based on e.g., resonance fluorescence. The present approach derives from recent experiments in which atoms and molecules are prepared by one (or more) coherent laser(s) and probed by another set of lasers. However, generating and using maximally coherent oscillation in macromolecules having an enormous number of degrees of freedom is challenging. In particular, the short dephasing times and rapid internal conversion rates are major obstacles. However, adiabatic fast passage techniques and the ability to generate combs of phase-coherent femtosecond pulses provide tools for the generation and utilization of maximal quantum coherence in large molecules and biopolymers. We call this technique FAST CARS (femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy), and the present article proposes and analyses ways in which it could be used to rapidly identify preselected molecules in real time. There is an urgent need for the rapid assay of chemical and biological unknowns, such as bioaerosols. Substantial progress toward this goal has been made over the past decade. Techniques such as fluorescence spectroscopy (1, 2) and UV resonant Raman spectroscopy (3-7) have been successfully applied to the identification of biopolymers, bacteria, and bioaerosols.At present, field devices are being engineered (1) that will involve an optical preselection stage based on, e.g., fluorescence radiation as in Fig. 1. If the fluorescence measurement does not give the proper signature then that particle is ignored. Most of the time the particle will be an uninteresting dust particle; however, when a signature match is recorded, then the particle is selected for special biological assay (see Fig. 1b). The relatively simple fluorescence stage can very quickly sort out some of the uninteresting particles whereas the more time-consuming bio-tests will be used for only the ''suspects.''The good news about the resonance fluorescence technique is that it is fast and simple. The bad news is that although it can tell the difference between dust and bacterial spores it cannot differentiate between spores and many other organic bioaerosols (see Fig. 1c).However, despite the encouraging success of the abovementioned studies, there is still interest in other approaches to, and tools for, the rapid identification of chemical and biological substances. To quote from a recent study (8): ''Current [fluorescence-based] prototypes are a large improvement over earlier stand-off systems, but they cannot yet consistently identify specific organisms because of the similarity of their emission spectra. Advanced signal processing techniques may improve identification.'' Resonant Raman spectra hold promise for being spore specific as indicated in Fig. 2b. This is the good news, the bad news is that the Raman signal i...

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Section: Fast Carsmentioning

confidence: 99%

FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

212

139

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“…In this subsection we demonstrate optical arbitrary pulse train generation (OAPTG) using spectral line-by-line pulse shaping, in which a pulse train spanning the whole period can be generated and individual pulses can be independently manipulated to have different user-specified waveforms [31]. This is in contrast to previous work on pulse train generation using Fourier transform pulse shapers in the group of lines pulse shaping regime [11,32,33], in which sequences of pulses with different shapes have been demonstrated, but only over a time aperture short compared to the repetition period. This limitation associated with the group of lines regime hinders capabilities for pulse train generation significantly, for example, even two-times RRM is impossible.…”

Section: Optical Arbitrary Pulse Train Generationmentioning

confidence: 99%

Spectral line‐by‐line shaping for optical and microwave arbitrary waveform generations

Huang

Jiang

Leaird

et al. 2008

Laser & Photonics Reviews

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Spectral line-by-line shaping is a key enabler towards optical arbitrary waveform generation, which promises broad impact both in optical science and technology. In this paper, generation of optical and microwave arbitrary waveforms using the spectral line-by-line shaping technique is reviewed. Compared to conventional pulse shaping, significant new physics arises in the line-by-line regime, where the shaped pulse fields generated from one laser pulse now overlap with those generated from adjacent pulses. This leads to coherent interference effects related to the properties of optical frequency combs which serve as the source in these experiments. We explore such effects in a series of experiments using several different high-repetitionrate optical combs, including harmonically mode-locked lasers and continuous-wave lasers that are externally phase modulated either with or without the help of an optical cavity. As an application of line-by-line pulse shaping, we describe generation of microwave electrical arbitrary waveforms that can be reprogrammed at rates approaching 10 GHz.Significance of line-by-line shaping: combining optical frequency combs with spectral pulse shaping

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“…Applications include coherent control of energy transfer in molecules, 1 selective Raman spectroscopy and microscopy, 2,3 separation and detection of isotopes and molecules, 4 probing of femtosecond structural dynamics of macromolecules 5,6 and coherent laser control of physicochemical processes. [7][8][9][10] Recently, methods based on holographic patterns 11 have been investigated as well as modulator based shapers with electro-optic, 12 acousto-optic, 13 or liquid-crystal spatial light modulators ͑SLM͒. [14][15][16] In the latter method the modulator is placed in the Fourier plane of the dispersed spectrum.…”

Section: Introductionmentioning

confidence: 99%

Compact high-resolution spectral phase shaper

Postma

Walle

Offerhaus

et al. 2005

Review of Scientific Instruments

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The design and operation of a high-resolution spectral phase shaper with a footprint of only 7 ϫ 10 cm 2 is presented. The liquid-crystal modulator has 4096 elements. More than 600 independent degrees of freedom can be positioned with a relative accuracy of 1 pixel. The spectral shaping of pulses from a broadband Ti:sapphire laser is verified by a hybrid cross-frequency-resolved optical gating/Grenouille measurement and intensity autocorrelation. We demonstrate the ability to split one pulse into two or more pulses with a programmable delay of more than 8.5 ps. To our knowledge this represents the most compact high resolution device in liquid-crystal modulator-based shaping to this date.

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Femtosecond laser pulse shaping by use of microsecond radio-frequency pulses

Cited by 272 publications

References 8 publications

FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

FAST CARS: Engineering a laser spectroscopic technique for rapid identification of bacterial spores

Spectral line‐by‐line shaping for optical and microwave arbitrary waveform generations

Compact high-resolution spectral phase shaper

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