Periodically poled ridge waveguides in KTP for second harmonic generation in the UV regime

Eigner, Christof; Santandrea, Matteo; Padberg, Laura; Völk, Martin; Rüter, Christian E.; Herrmann, Harald; Kip, Detlef; Silberhorn, Christine

doi:10.1364/oe.26.028827

Cited by 17 publications

(8 citation statements)

References 20 publications

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“…In KTP, for example, low-loss, strongly guiding waveguides can be realized by exchanging the highly mobile alkali ion, e.g., K + , for another substituent, e.g., Rb + or Cs + , by a simple diffusion process effectively creating mixed crystals, e.g., Rb 1−x K x TiOPO 4 [3,[8][9][10][11][12]. Other options include direct laser-writing, i.e., locally modifying the crystal via an intense, focused laser beam [13]; He-implatation [14]; or diamond-blade diced ridged waveguides [15].…”

Section: Introductionmentioning

confidence: 99%

“…Phase matching between interacting waves in any ferroelectric crystal can be realized independently of waveguide design by employing the quasi-phase matching scheme within periodically poled domain structures [15][16][17]. Periodically inverted domain structures can be fabricated by electric field poling via (lithographically) structured electrodes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Vibrational Properties of the Potassium Titanyl Phosphate Crystal Family

Neufeld,

Gerstmann,

Padberg

et al. 2023

Crystals

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The crystal family of potassium titanyl phosphate (KTiOPO4) is a promising material group for applications in quantum and nonlinear optics. The fabrication of low-loss optical waveguides, as well as high-grade periodically poled ferroelectric domain structures, requires a profound understanding of the material properties and crystal structure. In this regard, Raman spectroscopy offers the possibility to study and visualize domain structures, strain, defects, and the local stoichiometry, which are all factors impacting device performance. However, the accurate interpretation of Raman spectra and their changes with respect to extrinsic and intrinsic defects requires a thorough assignment of the Raman modes to their respective crystal features, which to date is only partly conducted based on phenomenological modelling. To address this issue, we calculated the phonon spectra of potassium titanyl phosphate and the related compounds rubidium titanyl phosphate (RbTiOPO4) and potassium titanyl arsenate (KTiOAsO4) based on density functional theory and compared them with experimental data. Overall, this allows us to assign various spectral features to eigenmodes of lattice substructures with improved detail compared to previous assignments. Nevertheless, the analysis also shows that not all features of the spectra can unambigiously be explained yet. A possible explanation might be that defects or long range fields not included in the modeling play a crucial rule for the resulting Raman spectrum. In conclusion, this work provides an improved foundation into the vibrational properties in the KTiOPO4 material family.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vibrational Properties of the Potassium Titanyl Phosphate Crystal Family

Neufeld,

Gerstmann,

Padberg

et al. 2023

Crystals

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Section: Introductionmentioning

confidence: 99%

“…More recently, it was demonstrated that KTP allows for the fabrication of ultra-short ferroelectric domain grids [4][5][6], i.e., submicron periods. These find application in efficient frequency conversion interfaces between the UV and mid IR that link photonics and solid-state quantum systems [6], mirrorless optical parametric oscillators [7], or counterpropagating parametric down-conversion (PDC) [8]. The latter provides spectrally decorrelated photons with narrower bandwidths and at higher source brightness than could be achieved with standard forward-propagating PDC and spectral filtering [8].…”

Section: Introductionmentioning

confidence: 99%

Non-Invasive Visualization of Ferroelectric Domain Structures on the Non-Polar y-Surface of KTiOPO4 via Raman Imaging

et al. 2021

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Potassium titanyl phosphate (KTP) is a nonlinear optical material with applications in high-power frequency conversion or quasi-phase matching in submicron period domain grids. A prerequisite for these applications is a precise control and understanding of the poling mechanisms to enable the fabrication of high-grade domain grids. In contrast to the widely used material lithium niobate, the domain growth in KTP is less studied, because many standard methods, such as selective etching or polarization microscopy, provides less insight or are not applicable on non-polar surfaces, respectively. In this work, we present results of confocal Raman-spectroscopy of the ferroelectric domain structure in KTP. This analytical method allows for the visualization of domain grids of the non-polar KTP y-face and therefore more insight into the domain-growth and -structure in KTP, which can be used for improved domain fabrication.

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“…Several techniques have been used to produce waveguides in KTP, e.g. ion-exchange [7], ridge waveguides [8,9] or laser writing [10]. Ridge waveguides offer a high mode confinement due to the substrate air boundaries, but the losses are rather high.…”

Section: Introductionmentioning

confidence: 99%

Evidence of nonlinear diffusion in KTP waveguides

Padberg¹,

Santandrea²,

Rüsing³

et al. 2020

Preprint

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Integrated χ (2) devices are a widespread tool for the generation and manipulation of light fields, since they exhibit high efficiency, small footprint and the ability to interface them with fibre networks. Surprisingly many things are not fully understood until now, in particular the fabrication of structures in potassium titanyl phosphate (KTP). A thorough understanding of the fabrication process and analysis of spatial properties is crucial for the realization and the engineering of high efficiency devices for quantum applications. In this paper we present our studies on rubidium-exchanged waveguides fabricated in KTP. Employing energy dispersive X-ray spectroscopy (EDX), we analysed a set of waveguides fabricated with different production parameters in terms of time and temperature. We find that the waveguide depth is dependent on their widths by reconstructing the waveguide depth profiles. Narrower waveguides are deeper, contrary to the theoretical model usually employed. Moreover, we found that the variation of the penetration depth with the waveguide width is stronger at higher temperatures and times. We attribute this behaviour to stress-induced variation in the diffusion process.

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Periodically poled ridge waveguides in KTP for second harmonic generation in the UV regime

Cited by 17 publications

References 20 publications

Vibrational Properties of the Potassium Titanyl Phosphate Crystal Family

Vibrational Properties of the Potassium Titanyl Phosphate Crystal Family

Non-Invasive Visualization of Ferroelectric Domain Structures on the Non-Polar y-Surface of KTiOPO4 via Raman Imaging

Evidence of nonlinear diffusion in KTP waveguides

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