Few-mode fiber based optical sensors

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Materials Science

Background:

• Few-mode fibers (FMFs) offer enhanced capabilities beyond standard single-mode fibers (SMFs) for optical communications and sensing.
• The spatial dimension in FMFs presents opportunities for multi-parameter sensing with improved discrimination.
• Existing optical fiber sensors often lack the multi-parameter sensing and discrimination capabilities achievable with FMFs.

Purpose of the Study:

• To report progress on Few-mode Fiber (FMF) based optical sensors.
• To demonstrate the potential of utilizing the spatial dimension of FMFs for multi-parameter sensing with discrimination.
• To explore both discrete and distributed FMF sensor configurations.

Main Methods:

• Fabrication and characterization of a discrete FMF sensor using modal interference between polarizations or spatial modes (LP01, LP11).
• Development of a distributed FMF sensor by generating stimulated Brillouin scattering (SBS) in a long FMF.
• Pump-probe configuration to characterize Brillouin gain spectrum (BGS) and measure temperature and strain coefficients for LP01 and LP11 modes.

Main Results:

• Demonstrated a discrete FMF sensor utilizing modal interference for sensing applications.
• Successfully implemented a distributed FMF sensor based on SBS in a long FMF.
• Quantified temperature and strain coefficients for LP01 and LP11 modes, showcasing mode-dependent sensing.

Conclusions:

• FMF-based optical sensors show significant potential for multi-parameter sensing with high discrimination capabilities.
• Both discrete interferometer and distributed SBS configurations in FMFs are viable for advanced sensing.
• The proposed FMF optical sensors can be applied to a wide range of sensing parameters, leveraging spatial mode properties.