Optical frequency-dependent opposite effective acoustic velocity dispersion in stimulated Brillouin scattering
Optical fibers serve not only as optical waveguides but also as acoustic waveguides, a dual functionality stemming from their structural properties and further enhanced by doping techniques. The effective velocity dispersion refers to the variation of acoustic mode velocity as a function of acoustic...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
AIP Publishing LLC
2025-05-01
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| Series: | APL Photonics |
| Online Access: | http://dx.doi.org/10.1063/5.0253737 |
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| Summary: | Optical fibers serve not only as optical waveguides but also as acoustic waveguides, a dual functionality stemming from their structural properties and further enhanced by doping techniques. The effective velocity dispersion refers to the variation of acoustic mode velocity as a function of acoustic wavelength or frequency. In the process of stimulated Brillouin scattering (SBS), it has long been considered that the effective velocity dispersion of all excited acoustic modes follows the same trend as each other in a fiber, primarily determined by acoustic waveguide dispersion. However, our recent study, based on accurate measurements of group/effective refractive indices and acoustic frequencies, reveals that the first two acoustic modes in a dispersion-shifted fiber exhibit opposite dispersion. In particular, over the pump wavelength range from 1535 to 1590 nm, the effective acoustic velocity of the fundamental mode decreases by 1.7 m/s as the acoustic frequency lowers, while the second mode increases by 3.1 m/s. They are in strong agreement with the predictions of our model considering anomalous acoustic dispersion. A similar phenomenon is also observed in highly nonlinear fiber. Our finding highlights the necessity of considering acoustic material dispersion in such dynamic processes, providing a deeper understanding of acoustic wave behavior during the SBS process in optical fibers. This insight can enhance optical fiber-based applications and contribute to the improved design of integrated photonic platforms. |
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| ISSN: | 2378-0967 |