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.

Design and fabrication of On-Chip Diamond Ring Resonators for Wavelength Conversion

Introduction and Background:

Wavelength conversion is vital for enhancing data transmission in telecom systems and enabling quantum state manipulation. Diamond stands out as an exceptional material for on-chip ring resonators due to its wide optical transparency (UV to THz), high thermal conductivity, and strong nonlinear optical properties. These attributes facilitate efficient wavelength conversion through four-wave mixing (FWM). Previous research, such as Hausmann et al. (2014), demonstrated a diamond resonator generating 20 new wavelengths around 1550 nm with a 20 mW threshold and a Q-factor of 1 × 10^6. However, key challenges remain to optimise the design, ensure fabrication feasibility, and validate performance through testing. This project addresses these aspects to assess the feasibility of such a device.

Project Objectives:

• Design: Develop an optimized diamond ring resonator, targeting key parameters (e.g., ring radius, waveguide width, coupling gap) to maximize FWM efficiency at telecom wavelengths (~1550 nm).
• Fabrication: Fabricating the resonator using current techniques at Kavli Cleanroom and with DOI substrates, identifying challenges like waveguide losses and proposing solutions.
• Testing: Create detailed plans and experimental testing of the device’s performance, including specific measurements like transmission spectra and conversion efficiency.

Expected Outcomes:

• Optimized Design: Comprehensive specifications for the resonator’s geometry and coupling setup, ensuring high-efficiency wavelength conversion.
• Fabrication Report: A detailed evaluation of fabrication challenges and outcomes (e.g., achieving waveguide losses below 1 dB/cm) with actionable solutions (e.g., improved patterning and etching methods).
• Testing: A clear outline of the experimental setup, testing key performance metrics (e.g., Q-factor, threshold power, conversion efficiency) and comparison with simulation-based predictions to guide validation.

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

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