Multilayer integration in silicon nitride: decoupling linear and nonlinear functionalities for ultralow loss photonic...

Area of Science:

• Integrated photonics
• Silicon nitride photonics
• Nonlinear optics

Background:

• Silicon nitride offers low optical loss and nonlinear properties suitable for on-chip optical signal processing.
• Integrating linear and nonlinear photonic functions on a single layer is challenging due to conflicting waveguide geometry requirements.
• Existing methods face tradeoffs between low optical loss for linear operations and efficient nonlinear performance.

Purpose of the Study:

• To demonstrate a dual-layer photonic integration approach using silicon nitride.
• To overcome the limitations of single-layer integration for combined linear and nonlinear photonic functions.
• To enable high-performance, ultralow-loss linear processing blocks alongside efficient nonlinear optical elements on a single chip.

Main Methods:

• Developed a dual-layer silicon nitride photonic platform.
• Individually optimized each silicon nitride layer for specific optical tasks: one for ultralow loss (linear processing) and the other for nonlinear operations.
• Demonstrated chip functionality by integrating a power-efficient microcomb with an arrayed waveguide grating demultiplexer.

Main Results:

• Achieved ultralow optical losses in the silicon nitride platforms, on the order of a few dB/m.
• Successfully integrated a microcomb and an arrayed waveguide grating demultiplexer on a single chip.
• Demonstrated the filtering of specific frequency comb lines, showcasing the combined linear and nonlinear functionality.

Conclusions:

• The dual-layer approach effectively separates and optimizes linear and nonlinear photonic functions on a single chip.
• This method significantly enhances the integration of diverse optical elements, paving the way for advanced photonic integrated circuits.
• Opens possibilities for fully integrated processing of Kerr nonlinear sources and complex photonic systems.