Waveguide-coupled drop filters on SOI using quarter-wave shifted sidewalled grating resonators

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Devices

Background:

• Waveguide coupled channel drop filters are crucial components in optical communication networks.
• Existing designs often suffer from reflections and require circulators, increasing system complexity and cost.
• Silicon-on-insulator (SOI) platforms offer excellent optical properties and fabrication compatibility for integrated photonic devices.

Purpose of the Study:

• To design, fabricate, and demonstrate novel waveguide coupled channel drop filters on an SOI substrate.
• To achieve high-performance filtering with reduced back reflections, enabling circulator-free operation.
• To validate device performance against numerical modeling and explore power tap-off capabilities.

Main Methods:

• Device design utilizing resonant power transfer via side-walled Bragg resonators with quarter-wave shifts.
• Fabrication on SOI substrate using electron-beam lithography and inductively coupled plasma (ICP) etching.
• Experimental characterization of filter performance, including rejection ratios, bandwidth, and power tap-off.

Main Results:

• Demonstration of waveguide coupled channel drop filters operating at 1550 nm on SOI.
• Fabricated devices with two coupled cavities achieved rejection ratios exceeding 20 dB.
• Measured 3-dB bandwidths of 110 GHz, closely matching numerical predictions, with approximately 16 dB power tap-off at resonance.

Conclusions:

• The developed SOI channel drop filters offer a circulator-free solution with high performance.
• The fabrication process using e-beam lithography and ICP etching is suitable for creating these advanced photonic devices.
• These filters show significant potential for enhancing the efficiency and reducing the complexity of optical communication systems.