Such effect was modeled using a threeenergylevel diagram within the sumoveressential states approach, assuming. We observed that the 2pa crosssection decreases quadratically with the temperature. Zscan technique is suitable to investigate this change in temperature. Chapter 1 introduction national chiao tung university. Spectral dispersion of ultrafast optical limiting in coumarin120 by white light continuum zscan. A technique by which absolute visibletonearinfrared 2pa spectra of degenerate nature can be determined via performing a single dispersive white light continuum wlc zscan has been realized. The excited state absorption spectrum reveals that. Capturing whitelight continuum during plasmaablation of single silk filament. T closed aperture zscan kerr lens focuses or defocuses light clipped by the aperture thus. Optical characterization facility coordinator institute. Midinfrared spectral broadening in an ultrafast laser inscribed gallium lanthanum sulphide waveguide john e. Broad band nonlinear optical absorption measurements of. The ones marked may be different from the article in the profile.
The energy losses of laser pulses caused by multiphoton absorption and conical emission have been measured respectively by zscan technique. Saturation of absorption was observed due to the ground state depletion for the three polymers. We use a whitelight continuum wlc zscan technique to measure the degenerate twophoton absorption spectrum and associated dispersion of the. Implementation of zscan technique with white light. For nd2pa measurements, excitation wavelengths of 1800 and 2500 nm and a white light continuum wlc probe ranging from 9501600nm were selected to acquire the nd2pa spectra from 12001800nm. Nonlinear optical absorption of organic molecules for applications. A technique by which absolute visibletonearinfrared 2pa spectra of degenerate nature can be determined via performing a single dispersive whitelight continuum wlc zscan has been realized. We present an experimental technique to determine the degenerate twophoton absorption 2pa spectra by performing a single zscan using a highspectralirradiance white light continuum wlc generated by a hollow core fiber.
All of the optics and mounts in this kit have been certified by our ph. We present a technique for rapid characterization of degenerate nonlinear absorption and refraction spectra using a femtosecond white light continuum wlc pulse to perform zscans. In this chapter, firstly we will study light intensity induced medium refractiveindex change phenomenon, i. We study the nonlinear optical response of a standard dye ir26 using the zscan technique, but with the white light continuum.
Other efforts described in this dissertation include the development of the dual arm zscan technique and its extension to measuring thin film nonlinearities in the. Pdf whitelight continuum zscan technique for nonlinear. Intensity of light open aperture zscan, tpa measurements. In addition to this effect, we also observed a small excited state absorption for pot. Our results showed that atra presents two 2pa allowed bands at 280 nm 2 h. Experimental setup for whitelight continuum generation and the zscan measurements.
Midinfrared spectral broadening in an ultrafast laser. The gray line in this figure displays the transmittance of the filter used to block part of the intense 775 nm laser employed. We report on zscan investigations of the nonlinear optical properties of thin pyrolytic carbon films and two and threelayer graphene films, utilizing an 800 nm pulsed laser generating ultrashort 180 fs pulses. The broadband nature of this pump permits us to measure the twophoton. This work investigates the twophoton absorption 2pa spectrum of alltrans retinoic acid atra in dmso solution, employing the wavelengthtunable zscan and whitelight pumpprobe techniques with femtosecond pulses. The characterization of absorptive nonlinearities liaros. In our investigation of nlo properties of layered sns, we used femtosecond laser based zscan technique. We present a single beam zscan technique using an intense, broadband, whitelight continuum wlc beam for the direct measurement of nonlinear absorption spectra. The continuum source of wavelength from 450 nm to 1650 nm has been generated from the photonic crystal fiber on pumping with 772 nm of ti. White light continuum zscan technique for nonlinear materials characterization article pdf available in optics express 1216. Hence, a reliable method to determine the twophoton absorption 2pa spectra of the synthesized 2pis used for 2pp structuring is crucial.
We use a whitelight continuum wlc zscan technique to measure the degenerate twophoton absorption spectrum and associated dispersion of the nonlinear refraction in znse. In this sense, the whitelight continuum allied to the zscan technique allows fast spectra determination in a broad spectral range. Whitelight continuum spectrum obtained from a water cell. For these experiments, 30ps fullwidth at halfmaximum fwhm pulses at 532 nm were produced by generating the second harmonic of a switched and modelocked nd.
Mainly study on the selfphase modulation optical kerr effect, the crossphase modulation optical kerr effect, and related light induced birefringence effect. The results for most compounds were found to yield good agreement between the two methods. White light continuum zscan technique for nonlinear materials characterization. In this work, the white light was generated in a commercial photonic crystal fiber pumped by femtosecond pulses from a ti. The nonlinear spectra from 450 nm up to 700 nm for the three polymers were obtained by means of the whitelight continuum zscan technique. Dispersive white light continuum single zscan for rapid. In order to accomplish this task, we employed the laser flash photolysis lfp technique in association with the whitelight continuum wlc zscan measurements. White light continuum for broadband nonlinear spectroscopy by. A nonlinear spectrometer using a white light continuum zscan. Excitedstate absorption investigation of a cationic. We present a technique for rapid characterization of degenerate nonlinear absorption and refraction spectra using a. We demonstrate the validity of the method by measuring the 2pa. Degenerate zscan measurements with whitelight continuum. Ultrafast thirdorder nonlinear optical properties of a novel 4methoxy4nitro chalcone by zscan and degenerate fourwave mixing techniques shivaraj maidur, parutagouda shankaragouda patil, k.
The method of interest to us is femtosecond pumpprobe spectroscopy where a broadband, weak, whitelight continuum wlc 710 pulse is used to probe a medium that is subjected to an intense pump pulse. Nearir white light continuum for broadband zscan nonlinear spectroscopy natalia munera, 1,2 peng zhao, 2 rodrigo acuna herrera, 1 david j. Experimental techniques for nonlinear material characterization. The white light continuum is generated by focusing 150fs pulses at 1110 nm in a 3cm cell filled with distilled water. Alternatively, it has also been shown that whitelight continuum wlc, produced by focusing infrared fspulses on water or sapphire, can also be used to determine the spectrum of optical nonlinearities using the so called wlc zscan technique. Ultrafast supercontinuum generation in bulk condensed media.
The spectral components of the wlc source are temporally and spatially dispersed to minimize nondegenerate twophoton absorption 2pa processes. Zscan measurements using femtosecond continuum generation. Instead of a monochromatic excitation wavelength, this technique uses a broadband white light continuum pulse. Osa dispersion of nonlinear refraction and twophoton. Liquid exfoliation of electronic grade ultrathin tinii. We present a rapid characterization technique for nonlinear absorption and refraction.
Twophoton absorption spectra of carotenoids journal of. Nonlinear propagation of fs laser pulses in liquids and. Nonlinear optical properties and femtosecond laser. Spectroscopy, zscan technique, nonlinear characterization of materials. The transient singlet absorption spectrum shows a reverse saturable absorption around the qband region 500650 nm and a small saturable absorption around 650 nm. Zscan for the characterization of transparent optical. This enables very high pulse to pulse stability compared to other methods of generating. Whitelight continuum zscan technique for nonlinear materials characterization article pdf available in optics express 1216. Pdf nearir white light continuum for broadband zscan. Optimization of broadband white light continuum in gases for zscan. The spectral components of the wlc source are separated by using a narrow band variable filter to minimize nondegenerate nonlinearities. Temperature effect on the twophoton absorption spectrum.
We present a technique for rapid characterization of degenerate nonlinear absorption and refraction spectra using a femtosecond whitelight continuum wlc pulse to perform zscans. Kar1, 1scottish university physics alliance, department of physics, school of engineering and physical sciences, david brewster building, heriotwatt university, edinburgh, eh11 4as, united kingdom. The nature of excitedstate absorption in polymethine and. We analyze the sign and magnitude of nonlinear refraction and absorption in these materials, given contradictory results in this respect in the literature.
The broadband nature of this pump permits us to measure the twophoton absorption spectrum of znse using only one beam. The broadband light emission from singlefilament d 0 3. The technique and analysis presented here is one such example. Development of heterogeneous catalysts the base of sno2. C f is the damping constant describing half width at halfmaximum of the. Osa whitelight continuum zscan technique for nonlinear. Balu m, hales j, hagan d, van stryland e opt express, 16. We observe a change in sign of the ultrafast nonlinear refractive index. Pdf spectral dispersion of ultrafast optical limiting in. Measurement of degenerate twophoton absorption spectra of. This cited by count includes citations to the following articles in scholar.
The use of broadband incident pulse enables us to probe saturable absorption sa and reverse. Because of the spectral resolution of the whitelight continuum zscan, we were able to observe a well defined structure in the twophoton absorption spectrum, composed by two distinct peaks. We present an experimental technique to determine the degenerate twophoton absorption 2pa spectra by performing a single zscan using. Measurement of temperature change in nonlinear optical. Zscan measurements of kerrs nonlinearity sample aperture z z. The result of this pumpprobe technique is the nondegenerate nla spectrum. Molecular structure of a alltrans bcarotene and b trans apo80carotenal. Whitelight continuum generation 35x103 30 25 20 15 10 5 0 intensity 400 500 600 700. These peaks, as well as the resonant enhancement of the nonlinearity, were modeled using the sumoverstates approach considering a fourlevel energy. At present, femtosecond sc represents a unique and versatile source of coherent radiation, whose wavelength range spans over a considerable part of the optical spectrum and by far exceeds the definition of the white light. Whitelight continuum zscan technique for nonlinear. The wlc is focused, using an achromatic lens, onto the nonlinear sample that is scanned along the zdirection, and the.
Zscan nonlinear sample water cell f30cm f10cm f12cm spectrometer whitelight continuum ir filter iris 150fs, 775nm figure 1. Zscan and whitelight continuum wlc pumpprobe techniques were utilized to obtain twophoton absorption crosssections. The results obtained show good agreement with those employing a single wavelength source, although much faster because of the. We have used the whitelight continuum wlc zscan technique to determine the degenerate twophoton absorption 2pa crosssection spectrum of poly2methoxy52ethylhexyloxy1,4phenylenevinylene mehppv. Pulse fluorometry using simultaneous acquisition of fluorescence and excitation, d. Electronic structure of liquid water from polarization. The hollow fiber was filled with argon ar gas at a pressure of 0. To determine the excitedstate crosssections at 532 nm, we used the openaperture zscan technique 911. Zscan and spatial selfphase modulation of a gaussian. Unraveling the twophoton and excited state absorptions of. Such a whitelight continuum wlc generated 450nm is again attributed to selfphase 800 figure 2.
Whitelight continuum zscan technique for nonlinear materials characterization. White light continuum generation, transient absorption, optical parametric oscillators, petta watt lasers and other applications books and references. This device is pumped by the picosecond pulses produced in shbc515 narrow bandwidth second harmonic generator and seeded by whitelight continuum generated by femtosecond pulses. Figure 2 a schematically displays the details of the single wavelength zscan technique experimental setup. Pdf experimental techniques for nonlinear material. Investigation of the nonlinear absorption spectrum of all. In this report, we investigate the influence of temperature on the twophoton absorption 2pa spectrum of alltrans.
985 286 356 1041 989 1368 392 1343 406 1358 1242 547 709 1228 1564 672 930 1437 988 350 1161 756 633 1245 584 997 1284 739 497 1026 42 760