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Second-harmonic generation in periodically poled bulk Rb-doped KTiOPO4 below 400 nm at high peak-intensities
KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.ORCID iD: 0000-0002-2508-391X
KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.ORCID iD: 0000-0003-2070-9167
2013 (English)In: Optics Express, ISSN 1094-4087, Vol. 21, no 2, 1395-1403 p.Article in journal (Refereed) Published
Abstract [en]

We demonstrate that bulk Rb-doped KTiOPO4 (RKTP) shows improved susceptibility to gray-tracking compared to flux-grown KTiOPO4. We show high-fidelity periodic poling of 1 mm thick RKTP with a period of 3.18 mu m for second harmonic generation at 398 nm with a normalized conversion efficiency of 1.79%/Wcm. The crystal is used to frequency-double 138 fs-long pulses with an efficiency of 20% and a peak intensity of 560 MW/cm(2) without visible gray-tracking signs. We demonstrate that two-photon absorption is the predominant mechanism limiting the SHG efficiency in this spectral range at high peak powers and high repetition rates.

Place, publisher, year, edition, pages
Optical Society of America, 2013. Vol. 21, no 2, 1395-1403 p.
Keyword [en]
Nonlinear optics, materials, Ferroelectrics, Harmonic generation and mixing
National Category
Other Physics Topics
URN: urn:nbn:se:kth:diva-116381DOI: 10.1364/OE.21.001395ISI: 000315989500004ScopusID: 2-s2.0-84874049906OAI: diva2:589228
Swedish Research Council

QC 20130220

Available from: 2013-01-17 Created: 2013-01-17 Last updated: 2014-01-14Bibliographically approved
In thesis
1. QPM Devices in KTA and RKTP
Open this publication in new window or tab >>QPM Devices in KTA and RKTP
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Even though KTiOPO4 (KTP) is considered to be one of the best nonlinear materials for quasi phase matched (QPM) frequency conversion in the visible and the near-infrared spectral regions, its use is often limited by poor material homogeneity, high ionic conductivity, a considerable linear absorption and photochromatic damage. On the other hand, the improved material homogeneity and the lower ionic conductivity of bulk Rb-doped KTP (RKTP) make this material an ideal alternative for fabrication of fine-pitch QPM gratings, while the arsenate isomorph KTiOAsO4 (KTA) promises a better performance in the green spectral region and adds the advantage of a wider transparency window in the infrared. Unfortunately, the available studies on these materials are limited and unable to answer the question whether RKTP and KTA are feasible alternatives to KTP in terms of periodic poling and optical performance. The optical performance of the QPM devices depends on the periodic poling quality, therefore, a detailed comprehension of domain-grating formation in the KTP isomorphs is highly desired. The goals of this thesis were to gain a better understanding of the periodic poling process in the KTP isomorphs, in order to study the specifics of ferroelectric domain engineering in KTA and RKTP, and to evaluate the optical performance of these isomorphs. Fine-pitch periodically poled structures were engineered both in KTA and RKTP crystals. It was demonstrated that QPM gratings with excellent quality and with periods as short as 8.49 μm can be fabricated in KTA crystals. Comparative transmission studies have shown that periodically poled KTA (PPKTA) crystals can be superior to KTP for QPM second harmonic generation in the visible spectral region due to lower linear absorption. It was also demonstrated that RKTP is a superior alternative to KTP for high-quality QPM grating fabrication. A consistent room-temperature periodic poling of 5 mm thick RKTP crystals with a period of 38.86 μm has been achieved. The obtained large aperture periodically poled RKTP (PPRKTP) crystals showed an outstanding QPM grating uniformity and excellent optical performance in optical parametric oscillator (OPO) applications. Moreover, it was shown that RKTP is less susceptible to blue-induced infrared absorption than KTP. Finally, a novel and a relatively simple method for self-assembling quasi-periodic sub-μm scale ferroelectric domain structure in RKTP crystals has been presented. It was shown that, after treatment in aqueous KOH/KNO3 solution, periodic poling of RKTP with planar electrodes resulted in one-dimensional ferroelectric domain structure with an average periodicity of 650±200 nm, extending over the whole 1 mm thick crystal. Such self-assembled structures in RKTP were used to demonstrate 5th order non-collinear QPM backward second harmonic generation.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2014. xiv, 98 p.
TRITA-FYS, ISSN 0280-316X ; 2013:71
QPM, periodic poling, KTP
National Category
Other Materials Engineering Other Physics Topics
urn:nbn:se:kth:diva-139475 (URN)978-91-7501-974-1 (ISBN)
Public defence
2014-01-31, sal FB52, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:00 (English)

QC 20140114

Available from: 2014-01-14 Created: 2014-01-13 Last updated: 2014-01-14Bibliographically approved

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Zukauskas, AndriusPasiskevicius, ValdasCanalias, Carlota
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