| 1. |
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| 2. |
- Canalias, Carlota, et al.
(författare)
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Backward quasi phase matched second harmonic generation in sub-micron periodically poled KTiOPO4
- 2005
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Ingår i: 2005 Conference on Lasers & Electro-Optics (CLEO), Vols 1-3. - WASHINGTON : OPTICAL SOC AMERICA. ; , s. 2264-2266
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Konferensbidrag (refereegranskat)abstract
- 1mm thick KTiOPO4 was poled with 720nm domain period by employing UV-lithography, chemical patterning and electric field poling. The structure was used to demonstrate 6 and 7 order quasi-phase matched backward second harmonic generation.
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| 3. |
- Canalias, Carlota, et al.
(författare)
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Backward quasi-phase-matched second-harmonic generation in submicrometer periodically poled flux-grown KTiOPO4
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:18, s. 181105-1-181105-3
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Tidskriftsartikel (refereegranskat)abstract
- A 1 turn thick flux-grown KTiOPO4 sample was poled with a 720 nm domain period by employing deep-UV laser lithography, chemical patterning, and electric field poling. An atomic force microscope was used to characterize the periodic domain structure. The sample was used to demonstrate sixth and seventh order quasi-phase-matched backward second-harmonic generation.
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| 4. |
- Canalias, Carlota, et al.
(författare)
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Progress in Sub-Micrometer Periodicity of Quasi-Phase Matching Structures
- 2009
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Ingår i: 2009 Conference on Lasers and Electro-Optics and 2009 Conference on Quantum Electronics and Laser Science Conference, CLEO/QELS 2009. - Washington, D.C. : IEEE. - 9781424451845 ; , s. 906-907
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Konferensbidrag (refereegranskat)abstract
- We report on the progress in fabrication of sub-micrometer ferroelectric domain gratings in KTiOPO4. Periods as short as 565 nm have been created in the bulk of the crystal by electric-filed poling.
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| 5. |
- Chesini, Giancarlo, et al.
(författare)
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All-fiber devices based on photonic crystal fibers with integrated electrodes
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:3, s. 1660-1665
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Tidskriftsartikel (refereegranskat)abstract
- A special kind of microstructured optical fiber is proposed and fabricated in which, in addition to the holey region (solid core and silica-air cladding), two large holes exist for electrode insertion. Either Bi-Sn or Au-Sn alloys were selectively inserted into the large holes forming two parallel, continuous and homogeneous internal electrodes. We demonstrate the production of a monolithic device and its use to externally control some of the guidance properties (e. g. polarization) of the fiber.
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| 6. |
- dos Santos, F. Eroni P., et al.
(författare)
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Evaluation of the third-order nonlinear optical properties of tellurite glasses by thermally managed eclipse Z-scan
- 2009
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 105:2
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Tidskriftsartikel (refereegranskat)abstract
- The third-order nonlinearity is measured for TeO2-ZnO-Na2O (TZN) glasses codoped with BaO, Nb2O5, and La2O3. The results for the sign and magnitude of the nonlinearity were obtained using a combination of the eclipse Z-scan with thermal nonlinearity managed Z-scan, whereas the Kerr shutter technique was employed to obtain the electronic time response of the nonlinearity, all performed with 76 MHz repetition rate 150 fs pulses at 800 nm. The results show a fast response (< 200 fs) and a nonlinear refractive index varying from 1.5 to 3.5x10(-15) cm(2)/W, depending upon glass composition. At the peak power level employed, nonlinear absorption was negligible. The results obtained are in good agreement with other tellurite compositions reported, confirming the electronic origin of the nonlinearity.
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| 7. |
- Fernandez, A. F., et al.
(författare)
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Chemical composition fiber gratings in a high mixed gamma neutron radiation field
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 53:3, s. 1607-1613
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Tidskriftsartikel (refereegranskat)abstract
- Fiber Bragg gratings are all-fiber wavelength-selective refractive index structures manufactured through UV exposure of optical fibers. Their applications range from WDM all-fiber filters, dispersion compensators and fiber laser resonators for optical telecommunication applications to different types of point or distributed optical fiber sensors for a large variety of applications. The nuclear industry is considering the use of photonic technology for data communication in the next generation of nuclear power plants. In addition, fiber Bragg grating sensors are being evaluated by the nuclear industry for structural integrity and temperature monitoring. This work aims to study, in harsh radiation environments, a new type of FBG referred to as chemical composition grating. These gratings differ from other types of FBG in that their refractive index structure is attributed to a change in the chemical composition. Chemical composition gratings have shown to be extremely temperature stable surviving temperatures in excess of 1000 degrees C. We have experimentally studied the effect of very harsh gammaneutron radiation on the properties of chemical composition gratings fabricated in a Ge-F doped silica optical fiber.
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| 8. |
- Fokine, Michael, et al.
(författare)
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High-temperature treatment of hydrogen loaded GeO2 : SiO2 glasses for photonic device fabrication
- 2006
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 352:07-jun, s. 494-499
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature treatment of hydrogen loaded silica- and germanium doped silica glass, also referred to as OH flooding, has been studied. The removal mechanism of hydroxyl groups in silica glass, during OH flooding, occurs by formation and diffusion of molecular hydrogen, while in germanium doped silica the main diffusion mechanism is attributed to diffusion of molecular water. UV exposure of OH flooded and non-treated germanium doped silica samples, from a ArF laser at 193 nm, show large changes in the asymmetric stretching vibration of Si-O-Si bridges, indicating compaction of the glass network. In addition, the thermal relaxation kinetics of the UV induced compaction are found to be similar for non-treated samples and OH flooded samples.
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| 9. |
- Fokine, Michael
(författare)
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Manipulating glass for photonics
- 2009
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Ingår i: PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE. - : Wiley. - 1862-6300. ; 206:5, s. 880-884
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Tidskriftsartikel (refereegranskat)abstract
- A generalized concept for local manipulation of three-dimensional glass materials is described. The basic principle is to use means to deposit energy into the material to enable localized and selective changes in the bond structure of the glass matrix, causing a localized modification of the thermal equilibrium properties of the material. The different regions of the glass will then behave differently when the sample is subsequently heated homogeneously. If the difference in the thermal dynamics between modified and un-modified regions is significant, thermal treatment of the material can result in a self-organizing structure. The aim here is to provide a generalized concept of differential systems and self-organizing structures, using chemical composition Bragg gratings as an example. In this case, differential diffusion results in self-organizing structures consisting of a variation of the chemical composition, with compositional features smaller than 250 nm.
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| 10. |
- Fokine, Michael, et al.
(författare)
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Poled glasses for optical devices
- 2008
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Ingår i: Photonics North 2008. - : SPIE. - 9780819473288 ; , s. 709918-
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Konferensbidrag (refereegranskat)abstract
- Thermal poling is an efficient way to induce optical second-order nonlinearity in different types of glasses, which typically have macroscopic inversion symmetry. In this paper we present a study on the current dynamics during thermal poling of glasses and relate these results to the formation dynamics of the depletion region, which is closely linked to the induced optical second order nonlinearity. Based on a simple theoretical viewpoint, supported by experimental results, we propose that thermal poling of glasses, and space-charge formation in dielectrics in general, can be viewed as an ionic RC circuit. This, to some extent modified view oil thermal poling in glasses, opens up new opportunities to study and control the depletion layer dynamics subsequently leading to better control of the thermal poling induced optical second order nonlinearity in glasses.
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| 11. |
- Fokine, Michael, et al.
(författare)
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Thermally induced second-order nonlinearity in silica-based glasses
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 87:17
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents the observation of second-harmonic generation in pure silica and germanium-doped glass samples after heat treatment at elevated temperatures followed by rapid quenching to room temperature. No applied voltage has been used and the samples do not contain crystals. The induced nonlinearity is located near the surfaces of the sample. The possible origin of the second-order nonlinearity is discussed.
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| 12. |
- Hirose, T., et al.
(författare)
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Waveguide writing by CO2 laser annealing on sputtered silica film
- 2006
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 352:07-jun, s. 664-668
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Tidskriftsartikel (refereegranskat)abstract
- We present a novel method for creating refractive-index structures in sputtered silica film using CO2 laser annealing. The silica film was prepared by radio frequency magnetron sputtering on silica substrate. Deposited film with the refractive-index 0.8% higher than that of the silica substrate was realized, with a propagation loss of 0.4 dB/cm. The refractive-index of the silica film could be reduced by CO2 laser annealing, enabling the formation of cladding structure for 2-D waveguide.
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| 13. |
- Liao, Guihua, et al.
(författare)
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Preparation and characterization of new fluorotellurite glasses for photonics application
- 2009
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 355:7, s. 447-452
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Tidskriftsartikel (refereegranskat)abstract
- Glasses based on (85 − x)TeO2–xZnF2–12PbO–3Nb2O5 (x = 0–40) system have been studied for the first time for fabricating mid-infrared optical fiber lasers. The thermal and optical properties including UV–Vis, Raman as well as FTIR spectra are reported. It is demonstrated that increasing the ZnF2 concentration to 30 mol% significantly increased the thermal stability of the glass. Adding ZnF2 also reduced the hydroxyl (OH) content of the glass resulting in lower optical absorption in the mid-infrared region, which is crucial for infrared laser applications. The glass absorption cut-off edge near 400 nm blue-shifts with increasing ZnF2 addition. Raman spectra show a depolymerization of the glass network with increasing transformation of TeO3+1 to TeO3 structures.
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| 14. |
- Maciel, Glauco S., et al.
(författare)
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Strong upconversion from Er3Al5O12 ceramic powders prepared by low temperature direct combustion synthesis
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 89:8
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Tidskriftsartikel (refereegranskat)abstract
- Crystalline ceramic powders of Er3Al5O12 were obtained by low temperature direct combustion synthesis. Irradiating the sample with a low-power continuous-wave infrared (1.48 mu m) diode laser led to ultraviolet, violet, blue, green, and red (380, 410, 456, 495, 525, 550, and 660 nm) emissions. The strong upconversion luminescence appeared to the eyes as an intense green color. The presence of efficient four- and three-photon frequency upconversion processes makes this material an excellent candidate for use in photonic devices based on upconverter phosphors.
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| 15. |
- Méndez, Alexis, et al.
(författare)
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Packaging process of fiber Bragg grating strain sensors for use in high-temperature applications
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this paper, we report the development of a new bonding agent and method for the surface mounting of optical fiber Bragg grating (FBG) strain and temperature sensors for use in high temperature environments--where there is a presence of water, moisture, dust, susceptibility to corrosion and/or elevated temperatures up to 800°C. To ensure a stable reflectivity response of FBGs and their survival at elevated temperatures, we are using chemical composition gratings (CCGs). The refractive index modulation in these gratings is caused by a chemical change, which results in a higher activation energy and stable behavior up to 1000°C. Samples of CCGs were successfully encapsulated and mounted onto metal shims. The packaged sensors were tested for strain (+/- 1000με) and temperature (to +400 °C) response. The encapsulated sensors display a linear response with an increase in the temperature sensitivity of the FBG, with a factor of ~ 28.34pm/°C, and a strain gauge factor of 1.7pm/με.
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| 16. |
- Pernice, P., et al.
(författare)
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Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass
- 2009
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 355:52-54, s. 2578-2582
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Tidskriftsartikel (refereegranskat)abstract
- Second harmonic generation properties have been studied in 23 K2O center dot 27Nb(2)O(5) center dot 50 SiO2 glass subjected to thermal poling. The poling-induced optical nonlinearity. with chi((2)) = 3.8 pm/V, has been related to structural modifications within a surface layer of a few microns on the anode side, as evidenced by means of confocal micro-Raman mapping along the sample thickness. The data indicate that the structural changes result from a charge transport process that causes network modifications in an alkali depleted layer whose thickness is comparable with that of the non-linear region. The Raman data also indicate that in the alkali depleted layer the network polymerization degree increases as a consequence of ion migration. The origin of the nonlinearity and the mechanisms activated by poling are discussed. The mechanism of non-bridging-oxygen to bridging-oxygen bond switching is proposed to explain ion migration and the subsequent structural changes in the glass.
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