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doctoral thesis
Nelinearni efekti interakcije lasera i atomskih para
Zagreb: University of Zagreb, Faculty of Science, 2010. urn:nbn:hr:217:610261
Vdović, Silvije
University of Zagreb
Faculty of Science
Department of Physics

Institutional repository: Repository of the Faculty of Science

Cite this document

Vdović, S. (2010). Nelinearni efekti interakcije lasera i atomskih para (Doctoral thesis). Zagreb: University of Zagreb, Faculty of Science. Retrieved from https://urn.nsk.hr/urn:nbn:hr:217:610261

Vdović, Silvije. "Nelinearni efekti interakcije lasera i atomskih para." Doctoral thesis, University of Zagreb, Faculty of Science, 2010. https://urn.nsk.hr/urn:nbn:hr:217:610261

Vdović, Silvije. "Nelinearni efekti interakcije lasera i atomskih para." Doctoral thesis, University of Zagreb, Faculty of Science, 2010. https://urn.nsk.hr/urn:nbn:hr:217:610261

Vdović, S. (2010). 'Nelinearni efekti interakcije lasera i atomskih para', Doctoral thesis, University of Zagreb, Faculty of Science, accessed 14 May 2024, https://urn.nsk.hr/urn:nbn:hr:217:610261

Vdović S. Nelinearni efekti interakcije lasera i atomskih para [Doctoral thesis]. Zagreb: University of Zagreb, Faculty of Science; 2010 [cited 2024 May 14] Available at: https://urn.nsk.hr/urn:nbn:hr:217:610261

S. Vdović, "Nelinearni efekti interakcije lasera i atomskih para", Doctoral thesis, University of Zagreb, Faculty of Science, Zagreb, 2010. Available at: https://urn.nsk.hr/urn:nbn:hr:217:610261

Metadata
TitleNelinearni efekti interakcije lasera i atomskih para
Title (english)Nonlinear effects in the interaction between the laser and the alkai vapor
AuthorSilvije Vdović
MentorGoran Pichler (mentor)
Committee memberDamir Veža (predsjednik povjerenstva)
Committee memberGoran Pichler (član povjerenstva)
Committee memberHrvoje Buljan (član povjerenstva)
GranterUniversity of Zagreb
Faculty of Science
(Department of Physics)
Zagreb
Defense date and country2010-07-15, Croatia
Scientific / art field,
discipline and subdiscipline		NATURAL SCIENCES
Physics
Universal decimal classification
(UDC)		53 - Physics
Abstract
Istraživana je nelinearna interakcija atomskih para alkalija i laserskih izvora u različitim uvjetima. Elektromagnetski inducirana transparencija nastaje zbog interakcije izmedu kontinuiranih lasera i atomskih para rubidija u V shemi vezanja stanja. Transparencija je ponajviše rezultat smanjenja populacije osnovnog nivoa zbog saturacije prijelaza vezanog jakim veznim laserom. Usporedbom s teorijskim modelom zaključeno je da, osim saturacije, i stvorena koherencija u atomima takoder doprinosi povećanju transparencije. Istražena je interakcija femtosekundnih pulseva s rezonantnim parama rubidija različitih koncentracija korištenjem tehnike frekventno razlučivog optičkog uzorkovanja (FROG). Efekti prostiranja femtosekundnih laserskih pulseva optički tankim sredstvom mogu se opisati stvaranjem 0-π pulseva kod kojih dolazi do značajnih vremenskih modulacija električnog polja pulsa. Dobiveni rezultati usporedeni su s teorijskim simulacijama prostiranja pulsa rezonantnim medijem u okviru linearne disperzijske teorije, čime su odredene granice primjene FROG tehnike na karakterizaciju kompleksnih pulseva. FROG tehnikom mjereni su i pulsevi nakon rezonantne nelinearne interakcije s gustim parama rubidija. Rezultat takve interakcije je konusna emisija. U okviru aproksimacije adijabatske slijednosti zbog različitog predznaka razlike izmedu centralne valne duljine pulsa i valne duljine najbliže rezonantne linije dolazi do prostornog samofokusiranja odnosno samodefokusiranja. U frekventnoj domeni dolazi do samomodulacije faze pulsa koja takoder ovisi o predznaku razlike valnih duljina pulsa i rezonantne linije. Mjerenja faze pulsa potvrdila su gore navedene teze kroz različito ponašanje spektralne i vremenske faze pulsa ovisno o položaju spektra pulsa u odnosu na rezonanciju. Degenerirano četverovalno miješanje (DFWM) femtosekundnih pulseva u natrijevim parama mjereno je u režimu tranzijentne rešetke u BOXCARS geometriji. Proučavan je vremenski razvoj UV emisije uzrokovane višefotonskom apsorpcijom u mediju kao i vremenski razvoj generiranog DFWM signala. Modulacije intenziteta tranzijenata objašnjavaju se kvantnim udarima zbog koherentnog pobudivanja stanja fine strukture. Period modulacije odreden je razlikom energija nivoa različitog spina. Modulacije eksponencijalno trnu u vremenu odredenom karakterističnim vremenom relaksacija koherencija.
Abstract (english)
This thesis examines nonlinear interaction between the alkali vapor and different laser sources in various conditions. Interaction between cw lasers and rubidium atomic vapor in the V coupling scheme produces electromagnetically induced transparency, where the main contibution to the induced transparency comes from nonlinear saturation effects on the strongly coupled transition. By comparing the theoretical model and experimental results it is shown that part of the induced transparency comes from coherences induced between the uncoupled transitions. Interaction between the femtosecond (fs) pulses and resonant rubidium atomic vapor is investigated using frequency-resolved optical gating (FROG) technique. Propagation of the fs pulses in the optically thin medium results in formation of 0-π pulses which have strong modulation of the electric field amplitude on a time scale of several ps. Since it is impossible to cover the whole time evolution of the 0-π pulse, the FROG reconstruction process can never be accurate enough. Propagation of nearly-resonant pulses through the optically thick rubidium vapor results in conical emission due to the self-focusing of the pulse in time domain and self-phase modulation in frequency domain. Using the adiabatic following approximation, it is shown that the physical processes depend on the sign of detuning of pulse wavelength from the rubidium resonance lines. The pulse electric field phase in both domains, retrieved from the FROG measurements, shows different behavior with respect to the sign of the pulse detuning. Degenerate four-wave mixing (DFWM) of femtosecond pulses in sodium vapor was performed in BOXCARS geometry. When on three-photon atomic resonance, transient grating signal appeared on the frequency of the third harmonic of fundamental frequency at negative delay times with modulations whose period corresponds to the energy difference between the coherently excited upper state fine stucture levels. In positive time delays signal appears at the fundamental frequency and there is no signal at third harmonic frequency. This is explained by destructive interference between the fundamental field and the field at the frequency of third harmonic. The amplitudes of modulations at negative time delays have exponential time dependence determined by the coherence relaxation time.
Keywords
Keywords (english)
Languagecroatian
URN:NBNurn:nbn:hr:217:610261
Study programmeTitle: Physics
Study programme type: university
Study level: postgraduate
Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika (doktor/doktorica znanosti, područje prirodnih znanosti, polje fizika)
Type of resourceText
Extent153 str.
File originBorn digital
Access conditionsOpen access
Terms of useLicence In copyright icon
Created on2017-08-24 11:50:11