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Seminar Announcement: Subhabrata Ghosh

posted Feb 22, 2016, 12:10 AM by Stefano Varas   [ updated Feb 22, 2016, 12:10 AM ]

Friday, 19 February 2016, 15:00
Sala Grande Palazzina B via alla Cascata 56/C

Eu-doped SiO2-HfO2-ZnO ternary waveguides: A hybrid glass-ceramic for integrated optics

Subhabrata Ghosh
Department of Physics, Indian Institue of Technology Kharagpur
Kharagpur-721302, West Bengal, India

We present on sol-gel fabrication and characterization of low-loss Eu-doped 70 SiO2 - (30 − x) HfO2 - x ZnO (x = 2, 5, 7 and 10 mol %) ternary glass-ceramic planar waveguides by dip-coating technique. Transmission electron microscopy and grazing incident X-ray diffraction experiments confirm the controlled growth of ZnO nanocrystals, encapsulated by an amorphous medium, with an average size of 3 nm to 25 nm, with an increase of ZnO concentration from x = 2 mol % to 10 mol % respectively, in the SiO2-HfO2 composite matrix. The effect of crystallization on the local environment of Eu-ions, within the ZnO nanocrystals embedded glass-ceramic matrix, is studied by photoluminescence spectra (PL), wherein an intense mixed valence state (divalent as well as trivalent) emission of Eu-ion is observed. The existence of Eu2+ and Eu3+ in the SiO2-HfO2-ZnO ternary matrix is confirmed by X-ray photoelectron spectroscopy. Importantly, Eu2+, 3+ doped, ZnO nanocrystals embedded ternary waveguides exhibited low-propagation losses (0.3 ± 0.2 dB/cm at 632.8 nm) and optical transparency in the visible region of electromagnetic spectrum, which makes the ZnO embedded SiO2-HfO2-ZnO ternary waveguides a viable candidate for the development of on-chip, active, integrated optic devices.
This seminar will give an overview of our results obtained recently. It concerns materials for compact waveguide lasers as well as on-chip integrated optic devices.
The talk will also give the actual research perspectives on the topic.

Keywords: Rare earth; Glass-ceramic; Integrated optics.

Stefano Varas,
Feb 22, 2016, 12:10 AM