Silicon Photonics Circuit Design and Fabrication Techniques

Silicon photonics integrates optical and electronic functions on a silicon platform, leveraging mature CMOS processes to produce compact, high-performance circuits for data communications, sensing and signal processing. Design flows begin with building blocks such as waveguides, couplers and interferometers, which are characterised and modelled for inclusion in process design kits. Robust simulation frameworks account for material dispersion, thermo-optic effects and fabrication tolerances. Fabrication techniques use 200–300 mm silicon-on-insulator wafers, deep-UV lithography and etch processes to define single-mode and multimode waveguides with sub-10 nm precision. Active components—modulators, detectors and, increasingly, on-chip light sources—are co-integrated via doped regions, heterogeneous materials or bonded III–V compounds. Yield and performance depend on stringent control of geometry and refractive index uniformity across the wafer, addressed through advanced metrology, statistical process control and variation-aware design. The convergence of compact modelling, high-throughput fabrication and scalable testing underpins deployment of photonic circuits in datacentre interconnects, lab-on-chip sensors and emerging quantum networks.

Research from Nature Portfolio

Recent studies have demonstrated a fully integrated broadband silicon waveguide light source fabricated in a 300 mm foundry process. A reverse-biased p-i-n diode embedded in a silicon waveguide emits near-infrared radiation via hot-carrier intraband transitions, modelled by a one-dimensional Planck radiation approach. The source delivers nanowatts of guided power with no deviation from standard CMOS steps and has been employed for on-chip interferometric characterisation and infrared absorption spectroscopy of liquid samples.

Advances in macromodel generation have produced a wideband parametric baseband technique for passive photonic circuits. By applying complex vector fitting with amplitude and frequency scaling, rational models preserve causality, stability and passivity across design variables. The resulting macromodels can be embedded in ordinary differential-equation solvers or circuit simulators, enabling time-domain simulations at arbitrary optical carriers and efficient optimisation of multi-wavelength photonic systems.

Silicon Photonics Circuit Design and Fabrication Techniques publication trend

The graph below shows the total number of articles in silicon photonics circuit design and fabrication techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Photonic integrated circuit (PIC): An optical circuit integrating multiple photonic functions on a single substrate.

Waveguide: A dielectric structure that confines and guides light by total internal reflection.

Mach–Zehnder interferometer (MZI): An interferometric device splitting and recombining light to measure phase shifts or filter spectra.

Process design kit (PDK): A library of component models and rules enabling standardised photonic circuit design.

Process variation: Unintended deviations in fabrication parameters affecting device geometry and refractive indices.

References

1. Broadband near-infrared emission in silicon waveguides. Nature Communications (2024).
2. Wideband parametric baseband macromodeling of linear and passive photonic circuits via complex vector fitting. Scientific Reports (2023).
3. Optical and geometric parameter extraction across 300-mm photonic integrated circuit wafers. APL Photonics (2024).
4. Process Variation-Aware Compact Model of Strip Waveguides for Photonic Circuit Simulation. Journal of Lightwave Technology (2023).