Investigation of nanophotonic lithium niobate waveguides for on-chip evanescent wave sensing

Fuente: arXiv
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Main Authors: Harper, Nathan A., Hwang, Emily Y., Kocheril, Philip A., Lam, Tze King, Cushing, Scott K.
Format: Preprint
Published: 2024
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author Harper, Nathan A.
Hwang, Emily Y.
Kocheril, Philip A.
Lam, Tze King
Cushing, Scott K.
author_facet Harper, Nathan A.
Hwang, Emily Y.
Kocheril, Philip A.
Lam, Tze King
Cushing, Scott K.
contents Thin-film lithium niobate is a promising photonic platform for on-chip optical sensing because both nonlinear and linear components can be fabricated within one integrated device. To date, waveguided sample interactions for thin-film lithium niobate are not well explored. Compared to other integrated platforms, lithium niobate's high refractive index, birefringence, and angled sidewalls present unique design challenges for evanescent wave sensing. Here, we compare the performance of the quasi-transverse-electric (TE) and the quasi-transverse-magnetic (TM) mode for sensing on a thin-film lithium niobate rib waveguide with a 5 mM dye-doped polymer cladding pumped at 406 nm. We determine that both modes have propagation losses dominated by scatter, and that the absorption due to the sample only accounts for 3% of the measured losses for both modes. The TM mode has better overlap with the sample than the TE mode, but the TM mode also has a stronger propagation loss due to sidewall and sample induced scattering (32.5 $\pm$ 0.3 dB/cm) compared to the TE mode (23.0 $\pm$ 0.2 dB/cm). The TE mode is, therefore, more appropriate for sensing. Our findings have important implications for on-chip lithium niobate-based sensor designs.
format Preprint
id arxiv_https___arxiv_org_abs_2403_04174
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Investigation of nanophotonic lithium niobate waveguides for on-chip evanescent wave sensing
Harper, Nathan A.
Hwang, Emily Y.
Kocheril, Philip A.
Lam, Tze King
Cushing, Scott K.
Optics
Applied Physics
Thin-film lithium niobate is a promising photonic platform for on-chip optical sensing because both nonlinear and linear components can be fabricated within one integrated device. To date, waveguided sample interactions for thin-film lithium niobate are not well explored. Compared to other integrated platforms, lithium niobate's high refractive index, birefringence, and angled sidewalls present unique design challenges for evanescent wave sensing. Here, we compare the performance of the quasi-transverse-electric (TE) and the quasi-transverse-magnetic (TM) mode for sensing on a thin-film lithium niobate rib waveguide with a 5 mM dye-doped polymer cladding pumped at 406 nm. We determine that both modes have propagation losses dominated by scatter, and that the absorption due to the sample only accounts for 3% of the measured losses for both modes. The TM mode has better overlap with the sample than the TE mode, but the TM mode also has a stronger propagation loss due to sidewall and sample induced scattering (32.5 $\pm$ 0.3 dB/cm) compared to the TE mode (23.0 $\pm$ 0.2 dB/cm). The TE mode is, therefore, more appropriate for sensing. Our findings have important implications for on-chip lithium niobate-based sensor designs.
title Investigation of nanophotonic lithium niobate waveguides for on-chip evanescent wave sensing
topic Optics
Applied Physics
url https://arxiv.org/abs/2403.04174