Postfabrication spectral tuning of multimode interference fiber-optic sensors

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Multimode interference (MMI) fiber-optic sensors face limitations in post-fabrication spectral tuning.
• Existing methods lack the ability to adjust interference spectra after manufacturing.

Purpose of the Study:

• To demonstrate a post-fabrication spectral tuning method for MMI fiber-optic sensors.
• To enable precise control over interference spectra without altering the fabrication process.

Main Methods:

• Utilized a commercial fusion splicer for localized diameter modification of multimode fiber (MMF) within a single-mode fiber-MMF-single-mode fiber (SMS) configuration.
• Developed a wavenumber-based analytical model considering effective radius and length variations of the MMF.
• Experimentally induced tapering and bulging of the MMF.

Main Results:

• Demonstrated spectral tuning by localized diameter modification of MMF.
• Observed shifts in the fourth-order interference peak wavelength towards shorter (tapering) and longer (bulging) wavelengths.
• Achieved good agreement between measured peak wavelengths and theoretical predictions.
• Showcased that diameter modification offers an alternative tuning mechanism compared to length variation alone.

Conclusions:

• Post-fabrication spectral tuning of MMI fiber-optic sensors is achievable through localized MMF diameter modification.
• The developed analytical model accurately predicts wavelength shifts due to diameter changes.
• This method provides a practical approach to tune MMI fiber-optic sensors after fabrication, enhancing their versatility.