Single mode tapered fiber-optic interferometer based refractive index sensor and its application to protein sensing

Area of Science:

• Photonics and Optics
• Biosensing Technology
• Spectroscopy

Background:

• Refractive index sensors are crucial for detecting changes in chemical and biological environments.
• Tapered fiber optics offer a platform for sensitive optical measurements.
• Mode coupling spectroscopy is a sensitive method for analyzing light-matter interactions in optical fibers.

Purpose of the Study:

• To demonstrate a refractive index sensor based on single mode tapered fiber.
• To apply this tapered fiber optic biosensor for detecting protein (gelatin) concentration in water.
• To analyze the mode coupling spectroscopy for sensing applications.

Main Methods:

• Fabrication of a single mode tapered fiber.
• Utilizing mode coupling spectroscopy based on core-cladding modes excited by the fundamental core mode.
• Operating the sensor at a wavelength of 1550 nm.
• Measuring wavelength shifts in the transmission spectrum to determine refractive index and protein concentration changes.

Main Results:

• The tapered fiber optic sensor demonstrated a refractive index sensitivity of approximately 1500 nm/RIU.
• The highest sensitivity achieved for protein concentration detection was 2.42141 nm/%W/V.
• The sensor's operation relies on the wavelength shift of the transmission spectrum due to mode coupling.

Conclusions:

• Single mode tapered fiber is a viable platform for developing sensitive refractive index and biosensors.
• The mode coupling spectroscopy approach enables precise detection of analytes like protein concentration.
• The developed biosensor shows promise for various biochemical sensing applications.