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Proceedings Paper

Interferometric method for measuring the refractive index profile of optical waveguides directly written in glass substrates by femtosecond laser
Author(s): P. Ferraro; L. Aiello; S. De Nicola; A. Finizio; R. Osellame; N. Chiodo; V. Maselli; G. Cerullo; P. Laporta
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Paper Abstract

Direct waveguide writing by femtosecond lasers is rapidly becoming a promising valid alternative to standard fabrication techniques. Significant research efforts are devoted to understanding the effects of interaction of the radiation with the material and determining the key parameters in the writing process. The assessment of a reliable fabrication process depends crucially also on the availability of high resolution inspection and measurement methods. In this paper we employ digital holography (DH) in a microscope configuration as the characterization tool for measuring the refractive index profile of the waveguides. The method offers the advantages of high spatial resolution, high sensitivity and it allows to determine an absolute value of refractive index change without the need of any calibration. We report on the optical characterization of optical waveguides operating at 1.5 micron wavelength in two commercial glasses written by a stretched-cavity femtosecond Ti:sapphire oscillator. Measurements made by DH have evidenced a strong dependence of the fabrication process on the type of glass substrate.

Paper Details

Date Published: 27 August 2005
PDF: 11 pages
Proc. SPIE 5858, Nano- and Micro-Metrology, 585804 (27 August 2005); doi: 10.1117/12.612889
Show Author Affiliations
P. Ferraro, Istituto Nazionale di Ottica Applicata - Istituto di Cibernetica del CNR (Italy)
L. Aiello, Istituto Nazionale di Ottica Applicata - Istituto di Cibernetica del CNR (Italy)
S. De Nicola, Istituto Nazionale di Ottica Applicata - Istituto di Cibernetica del CNR (Italy)
A. Finizio, Istituto Nazionale di Ottica Applicata - Istituto di Cibernetica del CNR (Italy)
R. Osellame, Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano (Italy)
N. Chiodo, Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano (Italy)
V. Maselli, Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano (Italy)
G. Cerullo, Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano (Italy)
P. Laporta, Istituto di Fotonica e Nanotecnologie del CNR, Politecnico di Milano (Italy)


Published in SPIE Proceedings Vol. 5858:
Nano- and Micro-Metrology
Heidi Ottevaere; Peter DeWolf; Diederik S. Wiersma, Editor(s)

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