Refractive index sensing characterization of a singlemode-claddingless-singlemode fiber structure based fiber ring...

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Laser Technology

Background:

• Fiber optic sensors are crucial for various sensing applications.
• Refractive index (RI) sensing is important in chemical and biological analysis.
• Existing fiber-optic sensors have limitations in sensitivity or linearity.

Purpose of the Study:

• To demonstrate the refractive index (RI) characteristics of a novel single-mode-claddingless-single-mode fiber structure filter based fiber ring cavity laser sensing system.
• To evaluate the linearity and sensitivity of the proposed sensor for RI measurements.
• To compare the performance of this sensor with existing fiber-optic sensors.

Main Methods:

• Fabrication of a single-mode-claddingless-single-mode fiber structure filter.
• Integration of the filter into a fiber ring cavity laser.
• Experimental measurement of lasing wavelength shifts in response to changes in ambient RI.
• Linear and parabolic fitting of the experimental data.

Main Results:

• The lasing wavelength exhibits a red-shift with increasing ambient RI.
• Linear fitting shows good linearity (determination coefficient of 0.993).
• A sensitivity of approximately 131.64 nm/RIU was achieved for aqueous solutions (RI 1.333 to 1.3707).
• A 2nd order polynomial fitting achieved a determination coefficient higher than 0.999 for more rigorous monitoring.
• The fiber laser demonstrated a signal-to-noise ratio (SNR) of ~50dB and a 3dB bandwidth of ~0.03nm.

Conclusions:

• The proposed fiber ring cavity laser sensor effectively measures refractive index.
• The sensor offers high sensitivity and good linearity, suitable for various applications.
• The sensor's performance is competitive with existing fiber-optic sensors, with potential for more rigorous monitoring.