Abstract
Laser modification of thin titanium film for precise loss control in lithium niobate optical waveguides was demonstrated. A simple ray model was used for analysis of optical losses induced by interaction of two orthogonal polarization modes of a Ti-indiffused channel optical waveguide in lithium niobate with a thin metal film on the substrate top surface. The theoretical estimations are in a good agreement with experimentally observed increase of the losses 0.95 and 1.05 dB/mm for TE- and TM-polarized modes respectively caused by 5 nm titanium film. Direct laser modification of the titanium film by a 976 nm laser beam with the threshold intensity up to 1 kW/mm2 was demonstrated. The formation of titanium oxide and titanium nitride during laser modification of the film was discovered via X-ray spectroscopy and explains optical losses reduction. The technique was applied for precise balancing of optical intensities in arms of Mach-Zehnder optical modulator, an associated increase of the extinction ratio from 30 to 48 dB was achieved.
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Acknowledgement
M. Parfenov and A. Shamrai acknowledge support by Peter the Great St. Petersburg Polytechnic University in the framework of the Program “5-100-2020”.
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Tronev, A.V. et al. (2020). Optical Loss Control in Lithium Niobate Waveguides via Direct Laser Modification of Covered Titanium Film. In: Galinina, O., Andreev, S., Balandin, S., Koucheryavy, Y. (eds) Internet of Things, Smart Spaces, and Next Generation Networks and Systems. NEW2AN ruSMART 2020 2020. Lecture Notes in Computer Science(), vol 12526. Springer, Cham. https://doi.org/10.1007/978-3-030-65729-1_35
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DOI: https://doi.org/10.1007/978-3-030-65729-1_35
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