Intensity at 1533 nm in the Yb3+ co-doped sample is more than 7 times larger than that of the sample with only Erbium spectral shape correspond to the typical Ytterbium absorption.
Effective energy transfer from Ytterbium to Erbium ions is demonstrated.
A. Chiasera, M. Montagna, C. Tosello, S. Pelli, G.C. Righini, M. Ferrari, L. Zampedri, A. Monteil, P. Lazzeri, "Enhanced spectroscopic properties at 1,5 mm in Er3+/Yb3+-activated silica-titania planar waveguides fabricated by rf-sputtering", Opt. Mat. 25 (2004) 117-122.
A first step towards EDPWA. On the planar waveguide was deposited 100nm of Chromium by sputtering and the resist (cod. 1811 by Shipley) by spinning. After the develop of the resist and the removing of the Chromium the etching of the active film was carried out by a wet chemical process with a buffered HF etch.
A. Chiasera, C. Armellini, S.N.B. Bhaktha, A. Chiappini, Y. Jestin, M. Ferrari, E. Moser, A. Coppa, V. Foglietti, P.T. Huy, K. Tran Ngoc, G. Nunzi Conti, S. Pelli, G.C. Righini, G. Speranza, "Er3+/Yb3+-activated silica-hafnia planar waveguides for photonics fabricated by rf-sputtering", Journal of Non-Crystalline Solids 355 (2009), pp. 1176–1179.
Direct writing of grating by Excimer Laser irradiation on Er3+/Yb3+-doped SiO2-GeO2 planar waveguides
G. Nunzi Conti, S. Berneschi, M. Brenci, S. Pelli, S. Sebastiani, G.C. Righini, C. Tosello, A. Chiasera, M. Ferrari, "UV photoimprinting of channel waveguides on active SiO2–GeO2 sputtered thin films", Applied Physics Letters 89 (2006) 121102-1–121101-3.
S. Sebastiani, G. Nunzi Conti, S. Pelli, G.C. Righini, A. Chiasera, M. Ferrari, C. Tosello, "Characterization of a highly photorefractive RF-sputtered SiO2-GeO2 waveguide", Optics Express 13 (2005) 1696-1701.
Direct writing of channel waveguide by Excimer Laser irradiation
Channel waveguide after irradiation with a total of 20 kJ/cm2; Single step replica of the mask pattern; WG is single mode @ 1550 nm; Propagation losses about 0.3 dB/cm - Same as in the planar waveguide.
G. Nunzi Conti, S. Berneschi, M. Brenci, S. Pelli, S. Sebastiani, G.C. Righini, C. Tosello, A. Chiasera, M. Ferrari,"UV photoimprinting of channel waveguides on active SiO2–GeO2 sputtered thin films", Applied Physics Letters 89 (2006), 121102-1 – 121101-3.
GeO2 Ultra-Transparent Glassceramics
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.
A. Chiasera, C. Macchi, S. Mariazzi, S. Valligatla, L. Lunelli, C. Pederzolli, D.N. Rao, A. Somoza, R.S. Brusa, M. Ferrari, "CO2 Laser irradiation of GeO2 planar waveguide fabricated by rf-sputtering", Optical Materials Express, Vol. 3, Issue 9, pp. 1561-1570 (2013), doi: 10.1364/OME.3.001561.
1-D Photonic Structures
1-D Er3+-activated dielectric microcavity
S. Valligatla, A. Chiasera, S. Varas, N. Bazzanella, D.N. Rao, G.C. Righini, M. Ferrari, “High quality factor 1-D Er3+-activated dielectric microcavity fabricated by RF-sputtering”, Optics Express (2012), Vol. 20 Issue 19, pp.21214-21222.
Disordered photonic structure
A. Chiasera, F. Scotognella, L. Criante, S. Varas, G. Della Valle, R. Ramponi, M. Ferrari, "Disorder in Photonic Structures Induced by Random Layer Thickness", Sci. Adv. Mater. 7 (2015), pp. 1207-1212, doi: 10.1166/sam.2015.2249.