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Second-order nonlinearities in the domain walls of periodically poled KTiOPO4
KTH, Superseded Departments, Physics.
KTH, Superseded Departments, Physics.ORCID iD: 0000-0002-2508-391X
KTH, Superseded Departments, Physics.ORCID iD: 0000-0001-7688-1367
2004 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 85, no 3, 375-377 p.Article in journal (Refereed) Published
Abstract [en]

The domain wall regions in periodically poled KTiOPO4 crystals were examined and found to give rise to phasematched second harmonic generation in the Cerenkov directions. This phenomenon is caused by the nonlinear coefficients d(11) and d(12), which are not present in single domain regions, but are nonzero at and close to domain walls. The appearance of these nonlinearities is attributed to strain, produced by the domain inversion process and results in the creation of a dc piezoelectric field.

Place, publisher, year, edition, pages
2004. Vol. 85, no 3, 375-377 p.
Keyword [en]
Ferroelectricity, Laser beams, Optical waveguides, Q switched lasers, Refractive index, Second harmonic generation, Transmission electron microscopy, X ray diffraction, Electric field poling, Electrostatic energy, Ferroelectric domain, Spatial coherence
National Category
Atom and Molecular Physics and Optics
URN: urn:nbn:se:kth:diva-23575DOI: 10.1063/1.1775031ISI: 000222680400009ScopusID: 2-s2.0-4043119651OAI: diva2:342274
QC 20100525 QC 20110926Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2015-03-30Bibliographically approved
In thesis
1. Optical parametric amplification with periodically poled KTiOPO4
Open this publication in new window or tab >>Optical parametric amplification with periodically poled KTiOPO4
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis explores the use of engineered nonlinear crystals from the KTiOPO4 (KTP) family as the gain material in optical parametric amplifiers (OPAs), with the aim to achieve more knowledge about the benefits and limitations of these devices. The work aims further at extending the possible applications of OPAs by constructing and investigating several efficient and well performing amplifiers.

An OPA consists of a strong pump source, which transfers its energy to a weak seed beam while propagating through a nonlinear crystal. The crystals employed in this work are members of the KTP family, which are attractive due to their large nonlinear coefficients, high resistance to damage and wide transparency range. The flexibility of OPAs with respect to different wavelength regions and pulse regimes was examined by employing various dissimilar seed and pump sources.

The possibility to adapt an OPA to a specific pump and seed wavelength and achieve efficient energy conversion between the beams, originates from quasi-phasematching, which is achieved in periodically poled (PP) nonlinear crystals. Quasi-phasematched samples can be obtained by changing the position of certain atoms in a ferroelectric crystal and thereby reversing the spontaneous polarisation.

In this thesis several material properties of PP crystals from the KTP family were examined. The wavelength and temperature dispersion of the refractive index were determined for PP RbTiOPO4, which is essential for future use of this material. Another experiment helped to increase the insight into the volumes close to domain walls in PP crystals

Further, several OPAs were built and their ability to efficiently amplify the seed beam without changing its spectral or spatial properties was studied. Small signal gains of up to 55 dB and conversion efficiencies of more than 35 % were achieved for single pass arrangements employing 8 mm long PPKTP crystals. Apart from constructing three setups, which generated powerful nanosecond, picosecond and femtosecond pulses, the possibility to amplify broadband signals was investigated. An increase of the OPA bandwidth by a factor of approximately three was achieved in a noncollinear configuration.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. x, 75 p.
Trita-FYS, ISSN 0280-316X ; 2005:62
nonlinear optics, optical parametric amplification, optical parametric generation, optical parametric oscillation
National Category
Atom and Molecular Physics and Optics
urn:nbn:se:kth:diva-531 (URN)91-7178-201-X (ISBN)
Public defence
2005-12-09, Sal FD5, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:15
QC 20101013Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2010-10-13Bibliographically approved

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