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Proceedings Paper

Vapor-phase proton-exchange in lithium tantalate for high-quality waveguides fabrication
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Paper Abstract

Vapor-phase proton-exchange has been applied to lithium tantalate for the first time, as a waveguide fabrication technique. This technique provides alpha-phase waveguides without the need for annealing. A sealed ampoule set-up has been used employing pure benzoic acid as the vapor source. Various waveguides have been realized and optically characterized by means of standard m-lines spectroscopy. The profile shape is a step plus an exponential tail toward the substrate, as that found for vapor-phase proton-exchange waveguides in lithium niobate. The total depth of the refractive index profile increases with the exchange time, following a linear diffusion model. The ordinary index change has been determined by an interferometric method, giving values that confirmed the alpha-crystallographic phase of the fabricated waveguides. The propagation losses have been measured with a new method using an isosceles coupling prism and an out-coupling objective. The values found for the different modes of the various waveguides ranged from 0.5 to 0.8 dB/cm. An aging phenomenon in the fabricate waveguides has been observed during the first month after the exchange process. The extraordinary index change decreased of 5 percent, while the optical depth increased of 2 percent. Application of this technology to periodically poled substrates for QPM devices seems feasible.

Paper Details

Date Published: 15 May 2001
PDF: 8 pages
Proc. SPIE 4277, Integrated Optics Devices V, (15 May 2001); doi: 10.1117/12.426789
Show Author Affiliations
Roberta Ramponi, Politecnico di Milano and Ctr. di Elettronica Quantistica e Strumentazione Elettronica (Italy)
Roberto Osellame, Politecnico di Milano and Ctr. di Elettronica Quantististica e Strumentazione Elettronia (Italy)
Marco Marangoni, Politecnico di Milano and Ctr. di Elettronica Quantistica e Strumentazione Elettronica (Italy)
Vera Russo, Politecnico di Milano and Ctr. di Elettronica Quantistica e Strumentazione Elettronica (Italy)


Published in SPIE Proceedings Vol. 4277:
Integrated Optics Devices V
Giancarlo C. Righini; Seppo Honkanen, Editor(s)

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