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Complex spectral filters in silicon waveguides based on cladding-modulated Bragg gratings.
Optics Express
|June 22, 2021
Summary
This study introduces a novel silicon waveguide geometry for fabricating complex spectral filters, overcoming fabrication challenges in integrated photonics. The new design enables precise control over spectral responses for advanced optical applications.
Area of Science:
- Integrated photonics
- Waveguide optics
- Nanophotonics
Background:
- Spectral filters are crucial components in integrated photonics for data and telecommunications, optical signal processing, and astrophotonics.
- Traditional sidewall-corrugated waveguide gratings face fabrication challenges on silicon-on-insulator (SOI) platforms due to required nanometer-scale corrugation.
- High-index contrast platforms like SOI demand precise fabrication for effective spectral filtering.
Purpose of the Study:
- To propose a novel waveguide geometry for designing complex Bragg filters with arbitrary spectral responses.
- To overcome fabrication limitations associated with traditional sidewall-corrugated gratings in SOI.
- To enable accurate synthesis of spectral shapes and coupling coefficients for integrated photonic devices.
Main Methods:
- Design of silicon waveguides with laterally coupled Bragg loading segments.
- Utilizing a delocalized mode field to reduce sensitivity to fabrication errors.
- Employing layer-peeling and layer-adding algorithms for synthesizing arbitrary target spectra.
- Developing cladding-modulated Bragg gratings.
Main Results:
- Demonstration of a novel geometry for complex Bragg filters in silicon waveguides.
- Successful synthesis of arbitrary spectral responses using layer-peeling and layer-adding algorithms.
- Experimental validation on an SOI platform showcasing 20 spectral notches with a 3-dB linewidth of 210 pm.
- Reduced sensitivity to fabrication errors due to delocalized mode field.
Conclusions:
- The proposed novel geometry and design methodology enable the creation of complex spectral filters with arbitrary responses in SOI.
- The delocalized mode field design enhances fabrication tolerance and control over spectral characteristics.
- This approach offers a viable solution for advanced spectral filtering in integrated photonic devices, addressing current fabrication hurdles.
