Nonlinear optical switching in regioregular porphyrin covalent organic frameworks

Covalent organic frameworks (COFs) have aroused immense scientific interest as an exhilarating class of porous materials due to their structure tunability and diverse properties. However, understanding of their response towards laser induced nonlinear optical (NLO) applications is in its infancy and demands prompt attention. Herein, we report three novel regioregular porphyrin based porous COFs, Por‐COF‐HH and its dual metalated congeners (Por‐COF‐ZnCu and Por‐COF‐ZnNi) with excellent NLO properties. Notably, intensity dependent NLO switching behavior was observed for these Por‐COFs, which is highly desirable for optical switching and optical limiting devices. Moreover, the efficient π‐conjugation and charge transfer transition in ZnCu‐Por‐COF enable a high nonlinear absorption coefficient (β=4470 cm/GW) and figure of merit (FOM = σ1/σo, 3565) values compared to other state‐of‐art materials including molecular porphyrins (β=~100‐400 cm/GW), metal‐organic frameworks (MOFs; β=~0.3‐0.5 cm/GW) and graphene (β=900 cm/GW)

Soda-zinc-aluminosilicate glasses doped with Tb 3+, Ce 3+, and Sm 3+ for frequency conversion and white light generation

Sodium-zinc-aluminosilicate (NaZAS) glasses doped with single or multiple rare earth ions (Ce 3+, Tb 3+, Sm 3+) were synthesized, and their characteristics investigated by m-line spectroscopy, absorption and luminescence spectroscopy, and micro-Raman spectroscopy. Blue-white light, with x = 0.24 and y = 0.24 CIE chromaticity coordinates, was obtained for the Tb 3+ singly-doped glass excited at 351 nm. In NaZAS glasses co-doped with Ce 3+ and Tb 3+ it was possible to observe a non-radiative energy transfer from Ce 3+ to Tb 3+ ions upon 320 nm excitation; the Ce 3+\u2192Tb 3+ energy transfer microscopic parameter and efficiency were obtained from the analysis of the cerium emission decay curve. Different concentrations of Ce 3+ and Tb 3+ ions in the same glass host give rise to blue and blue-green emissions, with different CIE coordinates. Optical waveguides were also produced in the samples by means of Ag +-Na + ion exchange process, and characterized. \ua9 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE)

Hybrid 1-D dielectric microcavity: Fabrication and spectroscopic assessment of glass-based sub-wavelength structures

Two different 1-D multilayer dielectric microcavities are presented, one activated by Er3+ ions fabricated by rf-sputtering and other one containing [email protected] quantum dots obtained by a hybrid radio frequency-sputtering/solution deposition process. The rare-earth activated cavity is constituted by an Er3+ -doped SiO2 active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO2/TiO2 layers. Starting from the deposition procedure used for this cavity a fabrication protocol was defined with the aim to combine the high reproducibility allowed by the sputtering deposition for the fabrication of multilayers structures with the ability of fabricate films activated with highly luminescent quantum dots dispersed in polymeric matrix. In this case the cavity was constituted by poly-laurylmethacrylate host matrix containing [email protected] quantum dots inserted between two Bragg reflectors consisting of 10 pairs of SiO2/TiO2 layers fabricated by rf-sputtering on SiO2 substrate. The thicknesses of the films of the Bragg reflectors were tailored in order to reflect the visible radiation at around 650 nm. Transmittance spectra were employed to assess the optical features of the single Bragg gratings and whole samples. Luminescence measurements put in evidence that emissions strongly influenced by the presence of the cavities for both the samples

CO2 Laser irradiation of GeO2 planar waveguide fabricated by rf-sputtering

GeO2 transparent glass ceramic planar waveguides were fabricated by a RF-sputtering technique and then irradiated by a pulsed CO2 laser. The effects of CO2 laser processing on the optical and structural properties of the waveguides were evaluated by different techniques including m-line, micro-Raman spectroscopy, atomic force microscopy, and positron annihilation spectroscopy. After laser annealing, an increase of the refractive index of approximately 0.04 at 1.5 µm and a decrease of the attenuation coefficient from 0.9 to 0.5 db/cm at 1.5 µm was observed. Raman spectroscopy and microscopy results put in evidence that the system embeds GeO2 nanocrystals and their phase varies with the irradiation time. Moreover, positron annihilation spectroscopy was used to study the depth profiling of the as prepared and laser annealed samples. The obtained results yielded information on the structural changes produced after the irradiation process inside the waveguiding films of approximately 1 µm thickness. In addition, a density value of the amorphous GeO2 samples was evaluated

SiO2-P2O5-HfO2-Al2O3-Na2O glasses activated by Er3+ ions: From bulk sample to planar waveguide fabricated by rf-sputtering

0.4 Er3+-doped 90.7 SiO2 – 4.4 P2O5 – 2.3 HfO2 – 1.7 Al2O3 – 0.7 Na2O planar waveguide was fabricated by multi-target rf-sputtering technique starting by massive Er3+-activated P2O5-SiO2-Al2O3-Na2O glass. The optical parameters were measured by m-line apparatus operating at 632.8, 1319 and 1542 nm. The waveguide compositions were investigated by Energy Dispersive X-ray Spectroscopy and its morphology analyzed by Atomic Force Microscopy. The waveguide exhibits a single propagation mode at 1319 and 1542 nm with an attenuation coefficient of 0.2 dB/cm in the infrared. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 28.5 nm bandwidth was observed upon TE0 mode excitation at 514.5 nm. The optical and spectroscopic features of the Er3+-activated parent P2O5-SiO2-Al2O3-Na2O glass were also investigated

CO2 Laser irradiation of GeO2 planar waveguide fabricated by rf-sputtering

GeO2 transparent glass ceramic planar waveguides were fabricated by a RF-sputtering technique and then irradiated by a pulsed CO2 laser. The effects of CO2 laser processing on the optical and structural properties of the waveguides were evaluated by different techniques including m-line, micro-Raman spectroscopy, atomic force microscopy, and positron annihilation spectroscopy. After laser annealing, an increase of the refractive index of approximately 0.04 at 1.5 μm and a decrease of the attenuation coefficient from 0.9 to 0.5 db/cm at 1.5 μm was observed. Raman spectroscopy and microscopy results put in evidence that the system embeds GeO2 nanocrystals and their phase varies with the irradiation time. Moreover, positron annihilation spectroscopy was used to study the depth profiling of the as prepared and laser annealed samples. The obtained results yielded information on the structural changes produced after the irradiation process inside the waveguiding films of approximately 1 μm thickness. In addition, a density value of the amorphous GeO2 samples was evaluated

Glass-based 1-D dielectric microcavities

We have developed a reliable RF sputtering techniques allowing to fabricate glass-based one dimensional microcavities, with high quality factor. This property is strongly related to the modification of the density of states due to the confinement of the gain medium in a photonic band gap structure. In this short review we present some of the more recent results obtained by our team exploiting these 1D microcavities. In particular we present: (1) Er3+ luminescence enhancement of the 4I13/2 → 4I15/2 transition; (2) broad band filters based on disordered 1-D photonic structures; (3) threshold defect-mode lasing action in a hybrid structure

GeO2 glass ceramic planar waveguides fabricated by RF-sputtering

GeO2 transparent glass ceramic planar waveguides were fabricated by a RF-sputtering technique and then irradiated by a pulsed CO2 laser. Different techniques like m-line, micro-Raman spectroscopy, atomic force microscopy, and positronbannihilation spectroscopy were employed to evaluate the effects of CO2 laser processing on the optical and structuralbproperties of the waveguides. The GeO2 planar waveguide after 2h of CO2 laser irradiation exhibits an increase of 0.04 inbthe refractive index, measured at 1542 nm. Moreover, the technique of laser annealing is demonstrated to significantlybreduce propagation loss in GeO2 planar waveguides due to the reduction of the scattering. Upon irradiation of the surfacebthe roughness decreases from 1.1 to 0.7 nm, as measured by AFM. Attenuation coefficients of 0.7 and 0.5 dB/cm at 1319 and 1542 nm, respectively, were measured after irradiation. Micro-Raman measurements evidence that the system embeds GeO2 nanocrystals and their phase varies with the irradiation time. Moreover, positron annihilation spectroscopy was used to study the depth profiling of the as prepared and laser annealed samples. The obtained results yielded information on the structural changes produced after the irradiation process inside the waveguiding films of approximately 1 μm thickness.Fil: Chiasera, A. . Consiglio Nazionale delle Ricerche. Istituto Di Fotonica e Nanotecnologie; ItaliaFil: Macchi, Carlos Eugenio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física de Materiales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil; ArgentinaFil: Mariazzi, S.. Università di Trento. Dipartamento di Fisica; ItaliaFil: Valligatla, S.. Consiglio Nazionale delle Ricerche. Istituto Di Fotonica e Nanotecnologie; Italia. University of Hyderabad. School of Physics; India. Università di Trento. Dipartamento di Fisica; ItaliaFil: Varas, S.. Consiglio Nazionale delle Ricerche. Istituto Di Fotonica e Nanotecnologie; ItaliaFil: Mazzola, M.. Consiglio Nazionale delle Ricerche. Istituto Di Fotonica e Nanotecnologie; ItaliaFil: Bazzanella, N.. Università di Trento. Dipartamento di Fisica; ItaliaFil: Lunelli, L.. Bruno Kessler Foundation; Italia. Consiglio Nazionale delle Ricerche. Istituto di Biofisica; ItaliaFil: Pederzolli, C.. Bruno Kessler Foundation; ItaliaFil: Rao, D. N.. University of Hyderabad. School of Physics; IndiaFil: Ringhini, G. C.. Centro Enrico Fermi; ItaliaFil: Somoza, Alberto Horacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto de Física de Materiales; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; ArgentinaFil: Brusa, R. S.. Università di Trento. Dipartamento di Fisica; ItaliaFil: Ferrari, M.. Consiglio Nazionale delle Ricerche. Istituto Di Fotonica e Nanotecnologie; Itali

Highly integrated lab-on-a-chip for fluorescence detection

We report the fabrication and validation of a microfluidic chip for fluorescence detection, which incorporates in the same glass substrate the microfluidic network, the excitation, the filtering, and the collection elements. The device is fabricated in a hybrid approach combining different technologies, such as femtosecond laser micromachining and RF sputtering, to increase their individual capabilities. The validation of the chip demonstrates a good wavelength selective light filtering and a limit of detection of a 600-nM concentration of Oxazine 720 perchlorate dye