Narrow Linewidth All-Optical Microwave Oscillator Based on Torsional Radial Acoustic Modes of Single-Mode Fiber
A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR<sub>2,m</sub>) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavit...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-01-01
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| Series: | Micromachines |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2072-666X/16/1/97 |
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| Summary: | A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR<sub>2,m</sub>) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavity. The main ring cavity provides forward stimulated Brillouin scattering gain and utilizes a nonlinear polarization rotation effect to achieve TR<sub>2,7</sub> mode locking. By combining the sub ring cavity with the main ring cavity and utilizing the Vernier effect, the TR<sub>2,7</sub> mode microwave photonic single longitudinal mode (SLM) output can be ensured. Meanwhile, the 6.281 Hz narrow linewidth of the TR<sub>2,7</sub> mode is achieved by reducing the intrinsic linewidth of the passive resonant cavity. The acoustic mode suppression ratio and side mode suppression ratio of the TR<sub>2,7</sub> mode were 43 dB and 54 dB, respectively. The power and frequency fluctuations of within 40 min were approximately ±0.49 dB and ±0.187 kHz, indicating good stability. At a frequency offset of 10 kHz, the TR<sub>2,7</sub> mode had a low phase noise value of −110 dBc/Hz. This solution can be used in various fields, such as high-precision radar detection, long-distance optical communication, and high-performance fiber optic sensing. |
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| ISSN: | 2072-666X |