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A Fast Linearly Wavelength Step-Swept Light Source Based on Recirculating Frequency Shifter and Its Application to
Quan Yuan1, Zhaoying Wang2, Lipei Song3
1Key Laboratory of the Ministry of Education on Optoelectronic Information Technology, School of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China. ewanyuan@tju.edu.cn.
Sensors (Basel, Switzerland)
|February 2, 2019
Summary
A new wavelength step-swept light source (WSSL) offers linear, fast wavelength sweeping for fiber Bragg grating (FBG) sensors. This enables highly accurate strain and temperature measurements, even for dynamic events.
Area of Science:
- Photonics and Optical Sensing
- Fiber Optic Sensors
- Advanced Light Sources
Background:
- Accurate measurement of static and dynamic strain/temperature is crucial for structural health monitoring.
- Existing wavelength-sweeping light sources often lack linearity and speed, limiting interrogation capabilities.
- Fiber Bragg Gratings (FBGs) are widely used sensors but require precise interrogation techniques.
Purpose of the Study:
- To propose and demonstrate a novel wavelength step-swept light source (WSSL) for enhanced FBG sensor interrogation.
- To achieve linear and high-speed wavelength sweeping for improved measurement accuracy and dynamic range.
- To validate the performance of the WSSL in measuring static and dynamic strain and temperature with FBG sensors.
Main Methods:
- A recirculating frequency shifter loop (RFSL) incorporating a single-side-band (SSB) modulator was employed to create the WSSL.
- The swept step and rate were precisely controlled via radio frequency (RF) signals applied to the SSB modulator.
- Wavelength-to-time mapping was utilized for interrogating FBG sensors under static and dynamic strain conditions.
Main Results:
- The WSSL demonstrated tunable swept steps (1.2 pm to 128 pm) and a swept rate up to 99 kHz over a 5.12 nm range.
- High interrogation linearity for strain (0.99944) and temperature (0.99946) was achieved due to the WSSL's linearity.
- Dynamic strain measurements showed a signal-to-noise ratio (SNR) over 40 dB at 100 Hz, with a sensitivity of 0.048 με/Hz1/2.
- The system successfully captured rapid strain frequency changes from 100 Hz to 500 Hz in real-time.
Conclusions:
- The proposed WSSL based on RFSL and SSB modulation offers a highly linear and fast wavelength-sweeping capability.
- This WSSL significantly enhances the interrogation linearity and dynamic performance of FBG sensors.
- The demonstrated system is suitable for real-time monitoring of both static and dynamic events with high precision.
Keywords:
fiber Bragg gratingsensor interrogationwavelength step-swept sourcewavelength-to-time mappingMore Related Videos
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