Broadband higher order mode conversion using chirped microbend long period gratings

Area of Science:

• Photonics and Optical Engineering
• Fiber Optic Sensors
• Waveguide Devices

Background:

• Long period gratings (LPGs) are crucial optical fiber components.
• Mode conversion in LPGs is essential for various photonic applications.
• Existing chirped LPG fabrication methods have limitations in bandwidth and efficiency.

Purpose of the Study:

• To propose and demonstrate a new scheme for fabricating chirped microbend long period gratings.
• To enhance the mode conversion bandwidth and efficiency between LP01 and LP11 modes.
• To achieve the first experimental demonstration of a non-linearly chirped LPG.

Main Methods:

• Development of a novel chirped microbend LPG fabrication scheme.
• Numerical simulations using coupled mode equations.
• Experimental validation of the proposed scheme and device performance.

Main Results:

• Achieved a 4.8-fold increase in the bandwidth of mode conversion (LP01 to LP11).
• Demonstrated a high conversion efficiency of 20 dB.
• Successfully fabricated and characterized a non-linearly chirped long period grating.

Conclusions:

• The proposed scheme effectively enhances mode conversion characteristics in LPGs.
• The novel non-linearly chirped LPG opens new possibilities for advanced optical signal processing.
• The findings are validated through both numerical and experimental investigations.