SiN for Chip-Scale Atomic Clocks

  • On 26 May, 2025

Imagine a clock so precise it could revolutionize GPS navigation, wireless communication, and more. This is the goal of the Chip-Scale Optical Atomic Clock (CSOC) project. At its heart lies LIGENTEC’s silicon nitride (SiN) platform, the foundational technology making SiN for chip-scale atomic clocks and precision timekeeping possible.

Why LIGENTEC’s SiN is Crucial for CSOC

LIGENTEC’s SiN platform is ideal for integrating the complex components of an optical atomic clock onto a single photonic integrated circuit. This is thanks to its:

  • Wide transparency range: It allows for efficient light transmission.
  • Ultra-low propagation losses: This minimizes signal degradation.
  • Absence of two-photon absorption: High optical powers can be used without efficiency loss.

These features make our SiN platform essential for advanced applications requiring chip-scale atomic clocks.

Microscope images by Ghent University of the on-chip mode-locked laser – a critical building block of the clock – on LIGENTEC’s SiN platform. (a) Top-down photograph of the mode-locked laser cavity including the micro-transfer printed semiconductor optical amplifier, (b), (c) Zoomed-in views of the optical transition for evanescent coupling, (d) Schematic cross-section of the amplifier.

Key Advantages of LIGENTEC’s SiN for CSOC

The CSOC project demands exceptional optical performance. Our SiN platform meets these demands with several key advantages:

  • Unrivaled low propagation losses: These losses are crucial for generating efficient, octave-spanning frequency combs. They also enable building heterogeneous extended-cavity laser sources with narrow linewidths.
  • Access to anomalous dispersion: LIGENTEC’s thick SiN platform allows for precise dispersion engineering in both normal and anomalous regimes. This is vital for generating broad optical comb spectra on a chip.
  • Absence of two-photon absorption: Our platform can handle high optical powers without incurring nonlinear losses, ensuring power-efficient device operation.
  • Micro-transfer printing-ready: A new process module ensures efficient evanescent coupling of light between a SiN waveguide and a heterogeneously integrated III-V semiconductor optical amplifier. This brings on-chip lasers and electrically pumped optical amplifiers to the forefront, enabling previously unattainable active functionalities on a single SiN chip.
  • Unique multilayer SiN stack: Different silicon nitride layers are combined on a single chip. This allows for frequency comb generation at telecom wavelengths alongside atomic interaction for clock referencing at visible light.
  • Accelerating innovation from prototype to production: LIGENTEC supports rapid prototyping and PIC development. We also offer high-volume manufacturing in an automotive-qualified 200 mm industrial foundry.

The Future of Precision Timekeeping with SiN

The CSOC project represents a significant leap in photonic integration and precision timekeeping. As a driving force behind SiN for chip-scale atomic clocks, we are proud to collaborate with partners like Ghent University, EPFL, DTU, and Menlo Systems. Together, we are unlocking new frontiers across various industries with our silicon nitride solutions.

To learn more about the innovative work in the CSOC project, visit their official website: http://csoc-project.eu/#funding.