A multi-D-shaped optical fiber for refractive index sensing.

Area of Science:

• Photonics and Optical Sensing
• Materials Science
• Nanotechnology

Background:

• Refractive index (RI) sensing is crucial for chemical, biological, and biochemical analysis.
• Existing optical fiber sensors face limitations in sensitivity and fabrication complexity.
• Novel fiber designs are needed to enhance sensing performance and applicability.

Purpose of the Study:

• To present a novel class of multi-D-shaped optical fiber for enhanced refractive index measurements.
• To investigate the fabrication process and mechanical properties of the proposed fiber.
• To evaluate the sensing performance of the multi-D-shaped optical fiber for aqueous solutions.

Main Methods:

• Fabrication of multi-D-shaped optical fibers using femtosecond laser pulses on multimode optical fibers.
• Characterization of fiber surface morphology using Atomic Force Microscopy (AFM).
• Assessment of mechanical strength through tensile testing.
• Evaluation of refractive index sensing performance using sucrose solutions of varying concentrations.

Main Results:

• Successfully fabricated multi-D-shaped optical fibers with 3 to 7 D-shaped zones, each measuring 100 μm depth, 250 μm width, and 1 mm length.
• AFM analysis revealed a mean core surface roughness of 231.7 nm, indicating a smooth surface.
• Tensile tests confirmed sufficient mechanical strength for further processing.
• Achieved a high resolution of 1.27 × 10⁻³ to 3.13 × 10⁻⁴ RIU for refractive indices ranging from 1.333 to 1.403.

Conclusions:

• The novel multi-D-shaped optical fiber offers a promising platform for highly sensitive refractive index sensing.
• The fabrication method is robust and yields fibers with adequate mechanical integrity.
• These fibers are attractive for applications in chemical, biological, and biochemical sensing in aqueous environments.