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Ultrasonic hydrophone based on short in-fiber bragg gratings
Applied Optics
|February 28, 2008
Summary
In-fiber Bragg gratings show limited effectiveness for megahertz acoustic field measurement due to standing waves. Short gratings and fiber desensitization significantly improve performance for ultrasonic sensing.
Area of Science:
- Photonics
- Acoustics
- Fiber Optic Sensing
Background:
- Fiber Bragg gratings (FBGs) are widely used for sensing applications.
- Measuring high-frequency acoustic fields presents unique challenges for sensor technology.
Purpose of the Study:
- To evaluate the feasibility of using in-fiber Bragg gratings for megahertz acoustic field measurement.
- To identify limitations and propose improvements for FBG-based ultrasonic sensing.
Main Methods:
- Investigated acoustic coupling between ultrasonic fields and in-fiber Bragg gratings.
- Analyzed the formation of standing waves within the fiber.
- Assessed grating performance with varying grating lengths and fiber desensitization levels.
Main Results:
- Acoustic coupling induced standing waves, complicating the system response.
- Standard FBGs were found to be ineffective probes for this application.
- Significant performance enhancement was achieved using short gratings and optimized fiber desensitization.
Conclusions:
- In-fiber Bragg gratings require specific configurations for effective megahertz acoustic field measurement.
- Short gratings coupled with appropriate fiber desensitization offer a viable path for ultrasonic sensing.
- Achieved a noise-limited pressure resolution of approximately 4.5 x 10(-3) atm/radicalHz.
