Photonic crystal fiber tip interferometer for refractive index sensing

Area of Science:

• Optoelectronics and Photonics
• Fiber Optic Sensors
• Nanomaterials

Background:

• Refractive index sensing is crucial in various fields, including chemical analysis and biomedical diagnostics.
• Existing fiber optic sensors often face limitations in sensitivity, resolution, or fabrication complexity.
• Photonic crystal fibers (PCFs) offer unique light-confining properties suitable for advanced sensing applications.

Purpose of the Study:

• To design and fabricate a novel interferometer based on a photonic crystal fiber (PCF) tip.
• To functionalize the PCF tip with a solid silica-sphere for enhanced refractive index sensing.
• To evaluate the sensor's performance for both refractive index and temperature measurements.

Main Methods:

• Fabrication involved splicing a single-mode fiber (SMF) to a PCF and creating a solid silica-sphere at the PCF tip using an arc discharge.
• The sensor's response was characterized by monitoring wavelength shifts in response to changes in refractive index and temperature.
• Experimental setup utilized standard optical spectral analysis techniques to measure interference patterns.

Main Results:

• The developed sensor demonstrated a high resolution of approximately 8.7×10⁻⁴ for refractive index sensing within the range of 1.33-1.40.
• The sensor exhibited a temperature sensitivity of about 10 pm/°C across the temperature range of 20-100 °C.
• Wavelength shift was observed to be the primary indicator for both refractive index and temperature variations.

Conclusions:

• The PCF-based interferometer with a silica-sphere tip is a promising platform for high-resolution refractive index and temperature sensing.
• The simple fabrication method and robust performance make this sensor suitable for practical applications.
• Further research could explore functionalization of the sphere for specific analyte detection.