Effective electro-optical coefficient determination of low finesse periodically poled lithium niobate waveguide resonator
Abstract Lithium niobate (LiNbO3), as a second-order nonlinear crystal, possesses sufficient linear electro-optic strength, making it a suitable substrate for integrated optical modulators. Waveguides fabricated by titanium diffusion into lithium niobate (Ti:LN) can guide both TE and TM polarization...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-07-01
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| Series: | Scientific Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.1038/s41598-025-05917-x |
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| Summary: | Abstract Lithium niobate (LiNbO3), as a second-order nonlinear crystal, possesses sufficient linear electro-optic strength, making it a suitable substrate for integrated optical modulators. Waveguides fabricated by titanium diffusion into lithium niobate (Ti:LN) can guide both TE and TM polarizations. Thus, a single-channel waveguide of suitably periodically poled Ti:PPLN can be used as a polarization converter for a desired wavelength. Consequently, the effective electro-optic coefficient of the Ti:PPLN waveguide for a specified polarization is of interest. This paper proposes a novel, compatible method to determine the effective electro-optic coefficient of a Ti:PPLN channel waveguide. The proposed technique, which has been experimentally investigated, is based on the phase difference induced by illuminating a low-finesse waveguide resonator from both end facets. By measuring the resulting difference in resonance wavelengths along with the residual last PPLN domain at both ends of the waveguide, the electro-optic coefficient $$r_{51}$$ is determined to be $$29.45 \pm 2.6\,\,\text {pm/V}$$ for a 15 mm-long Ti:PPLN channel waveguide. The in situ characterization method developed in this work enables direct measurement of electro-optic coefficients in integrated photonic circuits, providing essential performance parameters for optimizing phase modulators, polarization converters, and nonlinear frequency mixing devices while maintaining device integrity. |
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| ISSN: | 2045-2322 |