Third-Harmonic Interferometric Frequency-Resolved Optical Gating for Investigating Ultrafast Optical Phenomena on the Few-Cycle Scale
Hyyti, Janne (2013)
2013
Teknis-luonnontieteellinen koulutusohjelma
Luonnontieteiden tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2013-12-04
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201401201049
https://urn.fi/URN:NBN:fi:tty-201401201049
Tiivistelmä
The recently introduced characterization technique of third-harmonic interferometric frequency-resolved optical gating for ultrashort laser pulses is investigated. The first pulse retrieval software for this complete characterization technique is presented and used to conduct pulse retrievals for the first time. In addition, the physics of this measurement technique is studied, and a simple equation describing the trace is derived.
The subjects for the retrieval procedure are the measured traces for femtosecond laser pulses that have been guided through a thin film sample of either pure titanium dioxide or pure silicon dioxide. These experiments were conducted in the Max Born Institute of Berlin, Germany in 2012. Different combinations of modulational components of the interferometric trace are used in the simulations to produce three pulses for each of the two samples. The retrieved pulses are combined to produce two representative pulses for the thin films, completely describing the electric field envelope and the phase of the measured laser pulses. Full width at half maximum pulse widths of 10.1 fs and 15.7 fs are measured for the pulses of silicon- and titanium dioxide samples, respectively. The retrieved pulses are further examined by analyzing their spectral phases and the experienced group delay dispersion.
The significant difference observed in the pulse durations for the two samples is attributed to multiphoton absorption processes in the titanium dioxide thin film, although the exact mechanism of the noninstantaneous third-order polarization remains unclear. The intensity envelopes of the reconstructed pulses are harnessed to study the lifetime of this process using a deconvolution strategy. By convolving the pulse for silicon dioxide with a one-sided exponential decay function with a time constant of 6.5 fs, a third pulse is produced, perfectly replicating the retrieved pulse shape for the titanium dioxide sample.
This is one of the fastest phenomena ever measured with a Ti:sapphire laser. The measurement software presented in this work facilitates additional research on the subject, understanding of which could increase our knowledge of nonlinear optics. More light can be shed on the lifetime of the Kerr nonlinearity, a mechanism of elementary nature in the production of ultrashort pulses with the Ti:sapphire laser.
The subjects for the retrieval procedure are the measured traces for femtosecond laser pulses that have been guided through a thin film sample of either pure titanium dioxide or pure silicon dioxide. These experiments were conducted in the Max Born Institute of Berlin, Germany in 2012. Different combinations of modulational components of the interferometric trace are used in the simulations to produce three pulses for each of the two samples. The retrieved pulses are combined to produce two representative pulses for the thin films, completely describing the electric field envelope and the phase of the measured laser pulses. Full width at half maximum pulse widths of 10.1 fs and 15.7 fs are measured for the pulses of silicon- and titanium dioxide samples, respectively. The retrieved pulses are further examined by analyzing their spectral phases and the experienced group delay dispersion.
The significant difference observed in the pulse durations for the two samples is attributed to multiphoton absorption processes in the titanium dioxide thin film, although the exact mechanism of the noninstantaneous third-order polarization remains unclear. The intensity envelopes of the reconstructed pulses are harnessed to study the lifetime of this process using a deconvolution strategy. By convolving the pulse for silicon dioxide with a one-sided exponential decay function with a time constant of 6.5 fs, a third pulse is produced, perfectly replicating the retrieved pulse shape for the titanium dioxide sample.
This is one of the fastest phenomena ever measured with a Ti:sapphire laser. The measurement software presented in this work facilitates additional research on the subject, understanding of which could increase our knowledge of nonlinear optics. More light can be shed on the lifetime of the Kerr nonlinearity, a mechanism of elementary nature in the production of ultrashort pulses with the Ti:sapphire laser.