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

Abstract

Silicon nitride is an excellent material platform for its extremely low loss in a large wavelength range, which makes it ideal for the linear processing of optical signals on a chip. Moreover, the Kerr nonlinearity and the lack of two-photon absorption in the near infrared enable efficient nonlinear optics, e.g., frequency comb generation. However, linear and nonlinear operations require distinct engineering of the waveguide core geometry, resulting in a tradeoff between optical loss and single-mode behavior, which hinders the development of high-performance, ultralow-loss linear processing blocks on a single layer. Here, we demonstrate a dual-layer photonic integration approach with two silicon-nitride platforms exhibiting ultralow optical losses, i.e., a few dB/m, and individually optimized to perform either nonlinear or linear processing tasks. We demonstrate the functionality of this approach by integrating a power-efficient microcomb with an arrayed waveguide grating demultiplexer to filter a few frequency comb lines in the same monolithically integrated chip. This approach can significantly improve the integration of linear and nonlinear optical elements on a chip and opens the way to the development of fully integrated processing of Kerr nonlinear sources.

Optimization Method for Center Frequency Accuracy of High-Channel-Count Arrayed Waveguide Grating in Dense Wavelength Division Multiplexing Systems

“…Moreover, the rapid advancement of AWG technology has led to the diversification of material platforms used for its fabrication, including silicon [18,19], silica [20,21], SiN [22][23][24], InP [25], LNOI [3,26], and polymers [15,27]. Additionally, the application of AWG is not limited to individual devices anymore, as it can be integrated on-chip with other components, such as optical frequency combs [28], micro-ring resonators [29,30], and others. This allows AWG to achieve more versatile functionalities and further expand its two-dimensional and even three-dimensional integration approaches [28,31].…”

“…Additionally, the application of AWG is not limited to individual devices anymore, as it can be integrated on-chip with other components, such as optical frequency combs [28], micro-ring resonators [29,30], and others. This allows AWG to achieve more versatile functionalities and further expand its two-dimensional and even three-dimensional integration approaches [28,31].…”