Design, optimization and fabrication of an optical mode filter for integrated optics

Area of Science:

• Photonics and Optical Engineering
• Waveguide Optics
• Optical Communication Components

Background:

• Lateral misalignment of optical fibers can cause undesirable light "snaking" behavior in optical circuits.
• This snaking can degrade the performance of optical components like splitters.
• Controlling light propagation and polarization is crucial for efficient optical systems.

Purpose of the Study:

• To design, optimize, fabricate, and characterize a novel optical mode filter.
• To mitigate the snaking behavior of light due to input optical fiber misalignment.
• To improve the equilibrium of optical splitters by reducing polarization-dependent effects.

Main Methods:

• The optical mode filter was designed using Bézier curves and integrated as a bottleneck section in an optical waveguide.
• Fabrication and characterization were performed to assess the filter's performance.
• Experimental investigation focused on the equilibrium of an optical splitter before and after filter implementation.

Main Results:

• The optical mode filter effectively attenuates the snaking behavior of light.
• The filter's performance is dependent on the optical state of polarization.
• Significant improvement in optical splitter equilibrium was observed, specifically for the Transverse Magnetic (TM) mode.
• Measured optical losses introduced by the filter are as low as 0.28 dB.

Conclusions:

• The developed optical mode filter is effective in reducing light snaking and improving optical splitter performance.
• The filter demonstrates polarization-dependent behavior, offering selective mode control.
• The low optical losses make this filter a practical solution for optical circuit enhancement.