Polarization-insensitive one-dimensional guided-mode resonance filter operating at conical mounting

Area of Science:

• Optics and Photonics
• Nanophotonics
• Optical Filters

Background:

• Guided-mode resonance filters (GMRFs) are crucial optical components.
• Achieving polarization insensitivity in GMRFs, especially at non-traditional mounting angles, presents a significant challenge.
• Conical mounting offers unique optical configurations but complicates polarization control.

Purpose of the Study:

• To design and implement a polarization-insensitive one-dimensional guided-mode resonance filter (1D-GMRF) at conical mounting.
• To investigate the conditions for achieving polarization insensitivity under conical incidence.
• To validate the design through experimental fabrication and measurement.

Main Methods:

• Theoretical design and simulation of a 1D-GMRF.
• Optimization of grating parameters to simultaneously excite fundamental TE and TM waveguide modes.
• Experimental fabrication and characterization of the 1D-GMRF.
• Analysis of angle-resolved resonance spectra under conical mounting.

Main Results:

• A design guideline was established: simultaneous excitation of fundamental TE and TM modes ensures polarization insensitivity at conical mounting.
• The polarization-insensitive resonance wavelength is dependent on the azimuthal angle (ϕ) under conical mounting.
• Experimental results confirmed polarization insensitivity at a resonance wavelength of ~673 nm for specific conical mounting parameters (ϕ≈30°, θ≈11.2°), aligning with simulations.

Conclusions:

• Polarization-insensitive 1D-GMRFs can be realized at conical mounting by carefully optimizing grating parameters.
• The azimuthal angle plays a critical role in determining the conditions for polarization-insensitive operation.
• The demonstrated 1D-GMRF offers a promising solution for applications requiring polarization-independent spectral filtering in non-standard optical setups.