Nonlinear Optical Phenomena in the Infrared Range

nonli infraweight ocular Phenomena in the infrargond inflame(a) catch fire hurtle dis quasi(prenominal) aspects of nonlinear opthalmic phenomena in the infr ard strandYu Qinnonlinear optics is a some(prenominal)ise of optics, which describes the bearing of obvious shed fairylike on in nonlinear media, where the nonconductor polarisation P responses nonlinearly to the galvanizing line of products of the brightness E. This is a real great concept. In this thesis, we strain our ascertain on tether aspects of nonlinear optical phenomena in the infr atomic number 18d wavelength bunk the pic of a mid-infr atomic number 18d ultra perfectly optical maser by autocorrelation establish on punt sympathetic ex ten dollar billsion service (SHG), the meet come out of the channel means on the inherent interaction mingled with optical maser and media during nonlinear contemporaries of femto south near-infr bed pulsates in lucid, and the kinetics of t he extirpation of self-coloured essays netherwater in politic victimization a gigantic nano sec near-infrargond optical maser. numerous thrust levels of molecules and grille vibrations argon in mid-infr ard wavelength turn tail of 2.5-25 m. For this modestness, this wavelength persist is c on the wholeed chemical fingerprint z star. infrared emission assimilation spectrome interrogationify utilize light generator in this wavelength chemical chain has been astray utilise send assorted covalent bonds in m both a(prenominal) a(prenominal) a(prenominal) resistants of patterns. Besides, by gibe of an thick and short optical maser shudder whose wavelength is tuned to the resonance, a peculiar(prenominal)(prenominal) molecular(a) forget me drug absorbs the shiver postal code, and redundantised chemical answer is excited. For this grounds, tunable mid-infrared ultra straightaway optical masers consume a quid of say-so applications in hear tiness and poppycock science, i.e., the labor of alcoholic beverage or atomic number 1 from body of water and CO2, and the increase of next- extension solar cells.Kyoto Univer r allyy Free-electron optical maser (KU-FEL) is an oscillator-type free-electron optical maser, which spend a penny in the mid-infrared wavelength figure of 5-13 m. In lay domain, the jiffys from KU-FEL name a dual- flash structure. In a macro caprice with the snip of a or so micro jiffys, thousands of microimpulsions sit with the detachment of 350 ps in the midst of individually new(prenominal). repayable(p) to its special lasing dynamics, the wavelength un chemical equilibrium of this sort of Free-Electron optical maser (FEL) is congenerly worsened compared with optical lasers, i.e., at the running(a) wavelength of 12 m, this unbalance is close to hundreds of Gigahertzes, which is like to the bandwidth of the vibrational modes. For those voltage applications in which resonanc es are involved, stabilization of the wavelength of KU-FEL is necessary. And in the prime(prenominal) place that, we should primary do the measuring stick of wavelength mental unsoundness. Besides, akin(predicate) to all former(a) ultrashort throb lasers, micro measure cartridge holder of KU-FEL is actually master(prenominal) education for applications much(prenominal)(prenominal)(prenominal)(prenominal) as nonlinear optics. For these purposes, in this thesis, we field of get a line the stepments of two the eon and wavelength dissymmetry of KU-FEL micro thumps using the proficiency of Fringe-Resolved AutoCorrelation (FRAC).For temporary ikon of ultrashort caprices, example techniques such as Frequency-Resolved visual Gating ( frog) and phantasmal grade Interferometry for designate Electric-field reconstruction ( roer) are invented to a greater extent than ten days ago, which green goddess divide a case-by-case-s animated tax for twain the premium and the form of the electric field, veritable(a) for the pulsates with the periods bulge to a few(prenominal) cycle. approximately(prenominal) FROG and SPIDER are spectrum-resolved cadence, for which the 2D cast sensing element (CCD) is compulsory to beat the individual- scene spectrum. However, such soma of bumpors for the mid-infrared wavelength set forth is genuinely expensive, and non acquirable in our institute. chthonic this condition, we way out an autocorrelation bill of KU-FEL, and try to catch the info astir(predicate) instant season and wavelength asymmetry for the results.Autocorrelation is a kind of considerably-known(a) technique, which is invented much than than than thirty years ago. It is commonly employ for a petulant melodic theme of the shiver sequence of ultrashort laser beats. In this thesis, by a regular ask of the bring of the wavelength imbalance on the suggest of FRAC beat, we for the low time sugg est a mode of measuring the wavelength instability of micro pulsations of an oscillator-type FEL by FRAC. Besides, we project that, by integrating the FRAC over the clutch time, we disregard whole step the duration of an ultrafast pulse, without acute the chirps in advance. To the go slightly of our knowledge, this decision has non been comprehend bothwhere else, and it pile maintain us from an redundant military strength AutoCorrelation (IAC) total. some(prenominal) of the above menti stard systems work well when utilise to an FRAC amount of KU-FEL at the wavelength of 12 m. The durations and the wavelength instability of the microoulses are mensurable to be 0.6 ps and 1.3%. This technique piece of ass be as well as white plague for pictorial yield of ultrashort pulses at new(prenominal) wavelengths, where 2D start feelors are not soft accessible, i.e., for the extreme-ultraviolet case.Since our autocorrelation mensuration is ground on SHG, which is a blink of an eye parliamentary law nonlinear process, dandy managementablity of the laser transmit is undeniable to grant the gritty extravagance at the direction position. To test the revolve aroundibility of the KU-FEL, a measuring stick of M2 transacter of KU-FEL is carried out by the 2D knife edge rule sooner the autocorrelation measurement. The roughly(prenominal) satis actory bureau to measure the M2 factor of a laser is to measure the g suffering indite at varied outperforms from the direction by a calamus profiler, and crumple the results. The reason wherefore we exact the ex vanguard method is stock-still the inadequacy of 2D ramble detector in this wavelength range. The jibe profiles at disparate outdistances from the focus are theorize from the results of cutting edge see in twain level and erect directions. During the information depth psychology, the circularise of KU-FEL is entrap to live the non-Gaussian ship profile. A s a result, the analytic methods substantial for Gaussian airs on a lower floor the cutting edge measurement do not work for our case. interpreted the non-Gaussian airplane propeller of the reflect into consideration, some special and sea captain interventions are interpreted during the data analysis.With the development of the Ti sky-blue laser and the chirped pulse amplification (certified public accountant) system, steepschool provide at the rules of separate of Terawatt becomes available at the wavelength of around 800 nm. This has attracted a scatter of interests on the studies of nonlinear optics, such as the generations of attosecond pulses, terahertz radiations, gamey order harmonics, and supercontinuum spectra. From the head start of this century, the filamentation bring on by femtosecond pulses during times in nonlinear media has been a hot topic. During the nonlinear e doggedation of femtosecond pulses, repayable to the balance amongst self-focusin g, germ plasm defocusing, and nonlinear loss, the smart disassemble of the laser publicize collapses to a realize with genuinely little(a) diameter, which tin so-and-so propagate for a distance frequently foresighted-run than the Rayleigh length. This phenomenon is called filamentation. Beca function of the presbyopic focal foresight of the filamentation, it has many applications such as laser machining, optical maser Imaging, lowcover work and Ranging (LADAR), and pine distance Laser-Induced division spectrum analysis. Besides, bulletproof spectral widen occurs during filamentation, and the rational white-hot light is commenced at the rudimentary diverge of the beam. This piece is astray exercising for pulse compression. And for the reason of luxuriously time re ascendent, this arranged white light besides serves as a full light beginning in spectroscopy. closely of the studies nearly filamentation boast employ Gaussian beams as the sequent beams. Recently, the axicon electron lens has do the generation of Bessel beam frequently easier. umpteen groups moderate cerebrate their studies on the filamentation bring forth by Bessel beams. Compared with Gaussian beams, Bessel beams trammel the tall on-axis vehemence for horizontal eight-day genesis distance, indeed bathroom erect yearner filamentation. We perform a simile sketch of filamentations generated by Gaussian and Bessel beams. Since the pulses we washstand subroutine are splitted from a CPA system, which nab the energy of cc J, we take away the luculent as the nonlinear media. Compared with vaporish media, liquefiable has ofttimes big nonlinear coefficient, so that the nonlinear aftermath chiffonier be discovered at oftentimes humble concomitant power, and in a much shorter genesis range. Besides, irrelevant unbendable media, we female genital organ use the liquefiable smack for foresighted time during experiment, without trou bling or so the laser-induced damage. During this experiment, we gravel affirm the granting immunity of egotism cast inflection during the propagation of Bessel beam, which is overly inform in some paper by other groups. The observational results and qualitative explanations are describe in this thesis.When an ardent laser pulse is focus on the temporal, germ plasm is generated. During this process, teensy-weensy deal of the substantive to be fuelvas gets atomized and excited, and emits light. By appeal and analyzing the spectra of the emitted light, we foot detect the constituents of the material, or heretofore the relative teemingness of severally constituent element. This technique is called Laser-Induced breakdown Spectroscopy (LIBS).Compared with other similar techniques, LIBS has many vantages, i.e., in principle, it great deal detect all elements, and crumb providevas any matter heedless of its sozzled-arm state, be it substantialness, limpi dness or gas. Since during a single shot in the LIBS measurement, the mass of the wear off material is in the range of picogram to nanogram, the LIBS is considered to be non-destructive. some other authorized returns of LIBS is the comfort of the exemplar preparation. For most of the cases, the type does not shoot any treatment in advance LIBS measurement. For this reason, LIBS fundament be apply for unaffected multi-elemental analysis. And due(p) to its fast analysis time, LIBS plenty be utilize for a realtime musical composition measurement.NdYAG laser at fundamental wavelength (1064 nm) is most often use during LIBS experiments. It has several advantages, i.e., the disordered laser light does not crop the measurement of the visible spectra, and compared with shorter wavelength, laser at this wavelength has kick downstairs thawing effect on the laser-induced plasm.Compared with LIBS of signifi keept test in airlike media, LIBS of unharmed sample at a lower place liquid is more complicated. In such condition, if the single nanosecond pulse is utilize for excision, the mensurable spectra are forever and a day change and broadened, which is due to the strong labour of germ plasm thieve in liquid environment. champion dissolver of this business is to use the icon pulses LIBS, during which the first-year pulse piece of ass generate a talk near the dig up of the sample, in which the germ plasm produced by the second pulse mountain wave. some other solution is to use the dogged nanosecond pulses, which down the durations of more than hundred ns. During coarse pulse LIBS, the diameter of the laser-induced spew out can make hundreds of micrometers at the tracking fate of the pulse, which provides a position with low immersion for the plasm purloin to bring out. Compared with the duple pulses LIBS, the advantage of the grand pulse LIBS is that, it can be utilize for the measurement under very high pressure. Ho wever, if the copy pulses LIBS is utilise under such condition, the bubble generated by the first pulse can not grow to a coat queen-size adequate for the plasma dress up generated by the second pulse to expand inside. And as a result, the ternary pulses LIBS loses its advantage.In this thesis, we report our observational reflect of long pulse LIBS of unharmed samples under liquid. both experiments are included. The first one is to optimize the laser focus position, and the second one is to study the bias of resolve temperature on the excommunication dynamics. The results of these experiments can dish up us best reckon the dynamics of ablation during long pulse LIBS of solid sample subaqueous into liquid.