We present a single-shot cross-correlation technique based on the determination of the transversally emitted second harmonic generation by crystals with randomly distributed nonlinear ferroelectric domains. We implement it to the measurement of an ultrashort laser pulse temporal shape and duration evolution along the propagation path
We present a novel single-shot cross-correlation technique based on the analysis of the transversally emitted second harmonic generation in crystals with random distribution and size of anti-parallel nonlinear domains. We implement it to the measurement of ultrashort laser pulses with unknown temporal duration and shape. We optimize the error of the pulse measurement by controlling the incident angle and beam width. As novelty and unlike the other well-known cross correlation schemes, this technique can be implemented for the temporal characterization of pulses over a very wide dynamic range (30 fs–1ps) and wavelengths (800–2200 nm), using the same crystal and without critical angular or temperature alignment.
We present a novel single-shot cross-correlation scheme based on the measurement of the transverse second harmonic generation (TSHG) in crystals with randomly distributed nonlinear ferroelectric domains. We implement it to the measurement of the temporal shape of ultrashort laser pulses with unknown temporal profile. This technique combines the capability of typical intensity cross-correlation methods in pulse shape measurement with the advantages of the TSHG and ca be applied to a wide range of pulse durations and wavelength, without any requirement of angular alignment or temperature control.
Periodic inversion of ferroelectric domains is realized in a lithium niobate crystal by focused femtosecond near-infrared laser beam. One and two-dimensional domain patterns are fabricated. Quasi-phase matched frequency doubling of 815nm light is demonstrated in a channel waveguide with an inscribed periodic domain pattern with conversion efficiency as high as 17.45%.
Trull, J.; Wang, B.; Sola, I.; Wieslaw Krolikowski; Sheng, Y.; Vilaseca, R.; Cojocaru, C. Trobades Científiques de la Mediterrània Josep Miquel Vidal p. 9- Data de presentació: 2015-10-07 Presentació treball a congrés
We demonstrate infrared femtosecond laser-induced inversion of ferroelectric domains. This process can be realised solely by using tightly focused laser pulses without application of any electric field prior to, in conjunction with, or subsequent to the laser irradiation. As most ferroelectric crystals like LiNbO3, LiTaO3, and KTiOPO4 are transparent in the infrared, this optical poling method allows one to form ferroelectric domain patterns much deeper inside a ferroelectric crystal than by using ultraviolet light and hence can be used to fabricate practical devices. We also propose in situ diagnostics of the ferroelectric domain inversion process by monitoring the Cerenkov second harmonic signal, which is sensitive to the appearance of ferroelectric domain walls.
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We determine the initial chirp parameter and the duration of pulses down to 30 fs via single-shot autocorrelation method based on transverse second harmonic generation in crystals with random distribution of inverted nonlinear domains.
We show that the recently implemented single-shot transverse autocorrelation technique (TAC), which takes advantage of the second-harmonic light generated in transverse direction by a random nonlinear crystal and was shown to work for light pulses of 200 fs, can be extended to measure pulse duration and initial chirp of pulses with durations down to 30fs. This technique can be very useful for easy in-situ inspection of ultrashort light pulses.
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We determine the different initial chirp parameters of ultra-short pulses down to 30 fs via single-shot transverse auto-correlation method based on transverse second harmonic generation in SBN crystal with random distribution of inverted nonlinear domains. With the measured chirp and time duration parameters, we simulate the transverse auto-correlation traces and the corresponding pulse time duration evolutions, which have a good match with the experimental results
Cojocaru, C.; Wang, B.; Sola, I.; Parra, A.; Wieslaw Krolikowski; Sheng, Y.; Vilaseca, R.; Trull, J. International Conference on Transparent Optical Networks p. 1-3 DOI: 10.1109/ICTON.2015.7193436 Data de presentació: 2015-07 Presentació treball a congrés
The second order transverse autocorrelation technique, using a nonlinear crystal with a random-size and distribution of antiparallel nonlinear domains, has been recently proved to be an effective method for ultrashort pulse characterization in the range of 200 fs, allowing the pulse duration and initial chirp measurement . In this work we show that this method can be extended to the measurement of shorter pulses down to 30 fs. This technique permits an in-situ analysis of the pulse evolution and provides a simple way to measure the pulse chirp acquired during propagation in the optical system.
Pulse compression in dispersive strontium barium niobate crystal with a random size and distribution of the anti-parallel orientated nonlinear domains is observed via transverse second harmonic generation. The dependence of the transverse width of the second harmonic trace along the propagation direction allows for the determination of the initial chirp and duration of pulses in the femtosecond regime. This technique permits a real-time analysis of the pulse evolution and facilitates fast in-situ correction of pulse chirp acquired in the propagation through an optical system.