High-birefringence fiber loop mirror sensor using a WDM fused fiber coupler

Area of Science:

• Optoelectronics
• Fiber optic sensing
• Materials science

Background:

• Conventional highly birefringent (Hi-Bi) fiber loop mirror (FLM) sensors typically exhibit wavelength shifts in response to strain.
• Integrating wavelength-division multiplexing (WDM) couplers into FLM configurations presents unique opportunities for sensor design.
• Understanding the interplay between Hi-Bi fiber characteristics and WDM coupler integration is crucial for developing advanced fiber optic sensors.

Purpose of the Study:

• To propose and investigate an intensity-based Hi-Bi fiber loop mirror (FLM) sensor.
• To explore the effect of incorporating a wavelength-division multiplexing (WDM) fiber coupler within the FLM configuration.
• To characterize the sensor's response to applied strain, focusing on amplitude modulation of the spectral signal.

Main Methods:

• An intensity-based FLM sensor was constructed using a Hi-Bi fiber section and a WDM fiber coupler.
• The spectral response of the sensor was analyzed, considering the combined influence of the Hi-Bi fiber and WDM coupler.
• Strain was applied to the sensor's head, and its effect on the spectral signal's amplitude was measured.

Main Results:

• The proposed sensor demonstrated an intensity-based spectral response to strain, unlike conventional wavelength-shifting Hi-Bi FLM sensors.
• A sensitivity of (-2.2±0.4)×10(-3) με(-1) was achieved over a strain range of 300 με.
• The sensor exhibited self-referenced characteristics, indicating inherent stability and reliability.

Conclusions:

• The developed intensity-based Hi-Bi FLM sensor offers a novel approach for strain measurement.
• The integration of a WDM coupler enables amplitude modulation, providing a distinct sensing mechanism.
• The sensor's self-referenced nature and achieved sensitivity highlight its potential for practical applications in strain monitoring.