Ryoichi Ishihara

Associate Professor, Group leader

Qutech, Dep. Quantum and Computer Engineering, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology

Ishihara-lab focuses on the integration technologies for unconventional electronic systems; quantum computers, quantum sensors, neuromorphic computers, and biodegradable sensors. Our work involves new materials, scalable fabrication of electronic and photonic devices, and 3D heterogeneous integration, aiming to realize unconventional electronic systems.

Towards On-Chip All-Optical Switching and Modulation with DOI Substrate Platform

Introduction and Background:

Diamond-on-Insulator (DOI) substrates are a proven strength of our laboratory, offering a unique combination of diamond’s exceptional optical and thermal properties, along with scalable fabrication processes. These substrates provide a robust platform for integrated photonic devices that can operate at ultrafast speeds with minimal loss. Building on our existing DOI substrate technology, this project focuses on the design, fabrication, and testing of on-chip all-optical switches and modulators. The goal is to exploit diamond’s Kerr nonlinearity and low two-photon absorption to achieve ultrafast, high-power optical signal processing—vital for next-generation telecommunications, data centers, and quantum information systems.

Project Objectives:

Design and Simulation:

• Develop and simulate DOI-based photonic architectures (e.g., microring resonators, photonic crystal cavities) that exploit diamond’s Kerr nonlinearity.
• Optimize device geometries using tools like FDTD and FEM for maximum nonlinear efficiency and minimal loss.

Fabrication:

• Fabricate prototype devices directly on our established DOI substrates using precise nanofabrication techniques available at Kavli Cleanroom at TU Delft.

Testing:

• Characterize performance (switching thresholds, modulation speeds, insertion losses, thermal stability) with optical tests.
• Benchmark results against simulation predictions and state-of-the-art platforms.

Expected Outcomes:

Prototype Devices:

• Fabrication of photonic devices for on-chip all-optical switches and modulators with low thresholds and ultrafast response times.

Optimized Processes:

• Develop a reproducible fabrication workflow for DOI devices and establish performance metrics for future scalability.

Relevant References:

1. Hausmann, B. J. M., et al. (2014). “Diamond nonlinear photonics.” Nature Photonics, 8, 369–374.
2. Zhang, X., et al. (2024). “Calculation of coupling coefficients for diamond micro-ring resonators.” J. Appl. Phys., 135(7), 073106
3. arXiv:2502.03987
4. arXiv:2501.12831
5. Mi, S., Kiss, M., Graziosi, T. & Quack, N. Integrated photonic devices in single crystal diamond. J Phys Photonics 2, 042001 (2020).

Interested? Please contact Ryoichi Ishihara r.ishihara@tudelft.nl or Salahuddin Nur <S.Nur@tudelft.nl>