Ultrasensitive refractive-index sensors based on rectangular silica microfibers.

Area of Science:

• Photonics and Optical Sensing
• Materials Science
• Nanotechnology

Background:

• Refractive-index (RI) sensors are crucial for various applications, including chemical detection and biomedical diagnostics.
• Existing microfiber-based sensors face limitations in sensitivity and performance.
• Developing novel sensing platforms with enhanced sensitivity is a key research objective.

Purpose of the Study:

• To demonstrate an ultrasensitive refractive-index sensor.
• To investigate the polarimetric interference of a rectangular silica microfiber for sensing.
• To analyze the factors contributing to high sensitivity in the proposed sensor design.

Main Methods:

• Fabrication of a rectangular silica microfiber.
• Utilizing polarimetric interference for RI sensing.
• Experimental measurement of sensor sensitivity around RI of 1.33.
• Theoretical analysis of birefringence variation and dispersion properties.

Main Results:

• Achieved an ultrasensitive RI sensor with a measured sensitivity of 18,987 nm/RIU.
• Sensitivity is approximately one order of magnitude higher than previously reported microfiber devices.
• Theoretical analysis confirmed RI-induced birefringence variation and unique rectangular microfiber dispersion as key factors.
• Predicted further sensitivity enhancement when group birefringence approaches zero.

Conclusions:

• The rectangular silica microfiber sensor offers a significant advancement in RI sensing technology.
• The unique birefringence dispersion property of the rectangular microfiber is critical for achieving ultrahigh sensitivity.
• The sensor shows great potential for applications requiring highly sensitive refractive-index detection.