Ultra-short long-period fiber grating based on a micro air-channel structure

Area of Science:

• Photonics
• Fiber Optics
• Nanotechnology

Background:

• Long-period fiber gratings (LPFGs) are crucial optical sensing components.
• Conventional LPFGs often require longer fabrication lengths, limiting miniaturization.
• Minimizing device footprint is essential for integrated photonic systems.

Purpose of the Study:

• To propose and demonstrate a novel, ultra-short long-period fiber grating.
• To investigate the fabrication method for this compact LPFG.
• To evaluate the sensing performance, specifically refractive index and temperature sensitivity.

Main Methods:

• Fabrication using a femtosecond laser to inscribe inner waveguide arrays within a single-mode fiber.
• Employing hydrofluoric acid etching to create micro air-channels.
• Characterizing the device's optical properties and sensing capabilities.

Main Results:

• Successfully fabricated an LPFG with a length of 600 µm (five grating periods), the shortest reported to date.
• Achieved a high refractive index sensitivity of approximately 587.08 nm/RIU in the 1.34-1.365 RIU range.
• Demonstrated a low temperature sensitivity of ~12.1 pm/°C, minimizing thermal cross-talk.

Conclusions:

• The developed ultra-short LPFG offers a significant advancement in miniaturized optical sensing.
• The fabrication technique is effective for creating highly sensitive and compact photonic devices.
• This LPFG is well-suited for applications requiring precise refractive index measurements with reduced temperature interference.