Strong pump rejection filter for polarization-diverse silicon platforms.

Area of Science:

• Silicon photonics
• Integrated optics
• Metamaterials

Background:

• High optical rejection filters are crucial for silicon photonics circuits like quantum sources and spectrometers.
• Current methods using modal-engineered Bragg filters are limited to transverse-electric (TE) only platforms.
• This limits versatility in polarization-diverse applications.

Purpose of the Study:

• To propose and demonstrate a new approach for high-rejection filters in polarization-diverse silicon photonics.
• To overcome the limitations of TE-only filter designs.
• To achieve high optical rejection without compromising insertion loss or device footprint.

Main Methods:

• Combining non-coherent cascading of modal-engineered Bragg filters with anisotropy-engineered metamaterial bends.
• Utilizing Bragg filters for high rejection of the transverse-electric (TE) mode.
• Employing metamaterial bends to remove residual transverse-magnetic (TM) mode power.

Main Results:

• Demonstrated a novel filter approach for polarization-diverse platforms.
• Achieved optical rejection exceeding 60 dB.
• Maintained low insertion loss and device footprint.

Conclusions:

• The proposed method enables high-rejection filters in polarization-diverse silicon photonics.
• This technique expands the applicability of integrated wavelength filters.
• The approach is suitable for advanced photonic circuits requiring precise mode control.