| 1. |
- Malmstrom, Mikael, et al.
(författare)
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Waveguides in polycrystalline diamond for mid-IR sensing
- 2016
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Ingår i: Optical Materials Express. - 2159-3930 .- 2159-3930. ; 6:4, s. 1286-1295
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Tidskriftsartikel (refereegranskat)abstract
- 8 mm long channel waveguides were manufactured in polycrystalline diamond with inductively coupled plasma etching and characterized in terms of mode-profile and propagation loss in the 1.5 - 3.4 mu m spectral region. As proof of principle, the waveguides were evaluated in an evanescent field sensing setup targeting the CH absorption peak of isopropanol at similar to 3.4 mu m, showing good agreement with numerical finite element simulations. (C) 2016 Optical Society of America
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| 3. |
- Malmström, Mikael, 1982-, et al.
(författare)
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Diamond waveguides for mid-IR sensing
- 2014
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Ingår i: Optics & Photonics in Sweden. ; , s. 1-1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Mølster, Kjell Martin, 1992-, et al.
(författare)
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THz time-domain reflection spectroscopy of KTiOPO4
- 2019
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Konferensbidrag (refereegranskat)abstract
- There is an ongoing development of THz sources for high-field applications, especially with the view of potential for THz-driven particle accelerators. For such sources nonlinear materials with high optical damage threshold and low loss are required. KTiOPO4, (KTP) is a well-established material for nonlinear optical applications in the visible and near-IR region thanks to its large transparency, high nonlinear coefficient and damage threshold. Its reasonably low absorption [1, 2] and strong coupling to phonon-polariton degree of freedom [1]. This shows promise for efficient IR to THz conversionprocess. Indeed,Wu et al.[2] recently demonstrated its superiority to LiNbO3and LiTaO3in a back to back experiment. In view of this, it is important to determinethe spectrum of complex refractive index over larger spectral range and with higher accuracy than has been do so far. KTP is an orthorhombic crystal belonging to mm2 point group with a rather complex vibrational mode structure containing 192 degrees of freedom. Earlier spectroscopic studies of KTP have either lacked the possibility of directly extracting the complex refractive index [3] or been limited by absorption of the transmitted signal due to the strong resonances of KTP, limiting the spectral extenttoabout 2.5 THz [4]. In this work we utilize reflection THz time-domain spectroscopy (TTDS) to determine the spectrum of the refractive index, n, and the absorption coefficient, , between 0.5 THz and up to 7 THz for two eigenpolarizations on the (001) plane.
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| 5. |
- Mølster, Kjell Martin, 1992-, et al.
(författare)
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THz time-domain reflection spectroscopy of KTiOPO4
- 2019
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- Terahertz (THz) radiation has been of increasing interest in the last decades, for security, manufacturing, quality control, medical and security imaging applications. The field requires more efficient and affordable sources and nonlinear upconversion schemes point in this direction. KTiOPO, (KTP) is a well-established material for nonlinear optical applications in the visible and near-IR region thanks to its large transparency, high nonlinear coefficient and damage threshold. Its reasonably low absorption [1, 2] and strong polariton resonances [1] show promise for efficient IR to THz upconversion and Wu et al. [2] recently demonstrated its superiority to LiNbO3 and LiTaO3 in a back to back experiment. However, the complex refractive index needs to be measured before further power scaling is realistic.
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| 6. |
- Mølster, Kjell Martin, 1992-, et al.
(författare)
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Time-domain spectroscopy of KTiOPO4 in the frequency range 0.6–7.0 THz
- 2019
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Ingår i: OSA Continuum. - : Optical Society of America. - 2578-7519. ; 2:12, s. 3521-3538
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Tidskriftsartikel (refereegranskat)abstract
- We report on THz time-domain spectroscopy measurements of flux grown KTiOPO4 in the frequency range 0.6–7.0 THz (20 to 240 cm−1). Our results compare well with earlier Raman and far-infrared measurements. We theorize that the differences between the optical phonon mode resonances reported in the literature are due to what growth parameters and melt compositions are used to grow the crystals. We also report on a new feature at 1.4 THz (47 cm−1).
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| 7. |
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| 8. |
- Agate, B., et al.
(författare)
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Portable ultrafast blue light sources
- 2004
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Ingår i: OSA Trends Opt. Photonics Series. - 1557527709 ; , s. 651-652
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Konferensbidrag (refereegranskat)abstract
- An effective means of achieving a portable, ultrafast blue-light source using a variety of nonlinear media is demonstrated. We investigate the relative merits of aperiodically-poled bulk and waveguide nonlinear crystals in comparison to periodically-poled structures.
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| 9. |
- Agate, B., et al.
(författare)
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Portable ultrafast blue light sources designed with frequency doubling in KTP and KNbO3
- 2004
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X .- 1558-4542. ; 10:6, s. 1268-1276
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate an effective means of achieving compact, truly portable, and entirely self-contained ultrafast blue light sources. Using a variety of nonlinear media to achieve simple second-harmonic generation of a femtosecond Cr:LiSAF laser, we investigate the relative merits of aperiodically poled bulk and waveguide nonlinear crystals in comparison to periodically poled structures. Such a compact and convenient source of ultrashort laser pulses in the blue spectral region could be of great interest for on-site applications spanning a host of disciplines, such as biomedical imaging, optical micromanipulation, and high-resolution spectroscopy.
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| 10. |
- Arvidsson, G., et al.
(författare)
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Anordning i form av koherent ljuskälla baserad på frekvenskonvertering av ljuset från lasrar : [Controllable laser light source uses two laser sources to enable frequency mixing such that three or four new wavelengths may be generated]
- 1990
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Patent (populärvet., debatt m.m.)abstract
- The present invention concerns a coherent light source based on frequency conversion of the radiation from two lasers (20, 21) by frequency mixing in optical waveguides (10; 90), which are provided in a substrate (1). The wavelengths for the two lasers (20, 21) should be such, that the phase matching condition for the optically nonlinear frequency conversion is fulfilled in the waveguide structure (10; 90). The frequency conversion is accomplished in the form of frequency mixing, frequency doubling or down conversion in frequency by parametric oscillation so that in total three or four new wavelengths can be generated. By using integrated optics technique the output radiation can be controlled in various ways, for example be switched to different output waveguides, varied in intensity or colour balance.
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| 11. |
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| 19. |
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| 20. |
- Arvidsson, G., et al.
(författare)
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Vågledare samt förfarande för framställning av sådan : [Quasi-phase-matched optical waveguides and method of making same]
- 1988
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Patent (populärvet., debatt m.m.)abstract
- A waveguide (and a method for fabrication of a waveguide) for electromagnetic waves, arranged in an optically non-linear crystal substrate (1), such as LiNbO3, LiTaO3 or KTiOPO4, whereby a periodically domain-inverted structure, with periodically reversed ferroelectric polarity, is provided in a channel waveguide (6), having a higher refractive index than other parts of the substrate. The regions of reversed ferroelectric polarity are achieved by means of a heat treatment yielding a domain-inversion governed by a periodic perturbation in the crystal surface, obtained by use of a periodic mask structure on the crystal surface. The periodic structure is arranged in such a way that it constitutes a quasi-phase-matching structure. Thereby the waveguide is capable of converting light or radiation of a certain wavelength (certain wavelengths) to light or radiation of another predetermined wavelength (other predetermined wavelengths) with high efficiency.
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| 21. |
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| 22. |
- Barbosa Pereira, Joao Manoel
(författare)
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Optically poled fibers for electro-optic applications
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work presented in this thesis shows the development of optically poleddevices for use in electro-optic experiments. In the form of papers published,it describes three optical poling methods: green light poling (Paper I), poling with a UV lamp (Paper II), and corona discharge poling (Paper V).Applications using the poled components are studied in distributed sensingby exploring Rayleigh scattering in poled fibers (Paper III), intermodal interference in poled fibers (Paper IV), and FBG inscribed in poled fibers forvoltage sensing (Paper VI).In thermal poling, heat increases the mobility of added ions to the fiber.An external electric field displaces the charges creating a depletion regionclose to the anode, where the fiber core is usually positioned. The proximityof the metal electrode to the core can cause optical losses, making electrooptic applications less efficient. The need for additional dopant in the preformcan make the production of these devices expensive.Optical poling explores the presence of Ge E’ centers in the fiber core torelease charges after light excitation. These centers are already present in anyfiber with Ge in the core. This enables the development of a fiber for opticalpoling very similar to a standard telecom fiber, making it cheaper and easyto integrate with standard components. Optical poling does not rely on theformation of a depleted region in the cladding, and the core can be positionedfar from the metal electrodes. This advantage allows low-loss electro-opticcomponents to be fabricated.Optical poling is usually thought to have lower induced effects when compared with thermal poling. In this work, experiments with optical polingwere made to study the possibility of increasing the induced second-ordernonlinearities to a level comparable with thermal poling.The fabricated poled fibers were used to investigate their potential usein fiber sensing. The emphasis was to explore new technologies such as CPϕOTDR, few-mode fiber sensing, which gained attention in the latest years,and FBGs, which is a mature technology.The results presented in the Papers I-VI show the advances and potentialapplications explored.
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| 23. |
- Barrett, Laura, et al.
(författare)
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High-contrast coercive field engineering for periodic poling of RbKTiOPO4 with Ba2+/K+ ion-exchange
- 2024
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Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 32:8, s. 14252-14260
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a new method of coercive field engineering for periodic poling of RbKTiOPO4 (RKTP). By ion exchanging RKTP in a molten salt containing 7 mol% Ba(NO3)2 and 93 mol% KNO3 we achieve more than an order of magnitude difference in polarization switching time between the exchanged and non-exchanged regions. This method is used to fabricate periodic gratings of 2.92 µm in 1 mm thick bulk RKTP for second harmonic generation at 779 nm with a normalized conversion efficiency of 2%/Wcm. We show that the poled domain structures are stable at 300 °C, and that there is no bulk refractive index modification associated with the periodic ion exchange.
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| 24. |
- Barrett, Laura, et al.
(författare)
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Novel Coercive Field Engineering Method for Short Period KTiOPO4
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- The development of reliable periodic poling methods that allow for sub-µm quasi-phase matched (QPM) gratings and, at the same time, allow for waveguide implementation, is of paramount importance for a large number of applications. For instance, backward-wave optical parametric oscillators [1] are only viable if the QPM period is on the same order of magnitude as the wavelengths of the interacting waves. Furthermore, the integration of such QPM devices in a waveguide format would unveil countless possibilities in quantum optics employing the crystal as an ultrabright bi-photon source with unique spectral characteristics.
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| 25. |
- Baxter, G. W., et al.
(författare)
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Single-mode near-infrared optical parametric oscillator amplifier based on periodically poled KTiOPO4
- 2001
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 40:36, s. 6659-6662
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Tidskriftsartikel (refereegranskat)abstract
- A singly resonant, single-axial-mode, optical parametric oscillator (OPO) based on periodically poled KTiOPO4 (PPKTP) is reported. Signal (1.68 mum) and idler (2.90 mum) optical bandwidths have been narrowed to < 400 MHz by use of a diffraction grating at grazing incidence. The OPO generates 370 muJ of signal radiation when pumped by 3.1 mJ of 1.064-mum radiation. We implemented a single-pass PPKTP amplifier to yield 2.15-mJ signal and 1.17-mJ idler radiation without broadening the spectral bandwidths.
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