Silicon-based polarization-insensitive optical filter with dual-gratings.

Area of Science:

• Photonics
• Integrated Optics
• Materials Science

Background:

• Polarization-insensitive optical filters are crucial for integrated photonic circuits.
• Existing designs often struggle with performance across different polarizations.
• On-chip optical components require compact and efficient solutions.

Purpose of the Study:

• To propose and demonstrate a novel silicon-based polarization-insensitive optical filter.
• To achieve high performance metrics for both TE and TM polarizations.
• To reduce reflections and suppress unwanted resonances and sidelobes.

Main Methods:

• Design of a dual-polarization mode (de)multiplexer.
• Utilizing a TE-type multimode waveguide grating (MWG) with triangular corrugations.
• Employing a TM-type MWG with rectangular corrugations and lateral-shift apodization.

Main Results:

• The fabricated device exhibits a 3 dB bandwidth of approximately 11 nm for both polarizations.
• Measured excess loss is around 1.5 dB for both TE and TM modes.
• Sidelobe suppression ratios of 23 dB (TE) and 17 dB (TM) were achieved.

Conclusions:

• The proposed silicon-based optical filter effectively achieves polarization insensitivity.
• The design incorporates specific corrugation shapes and apodization for enhanced performance.
• This filter offers a promising solution for advanced integrated photonic applications.