Design and fabrication of three-dimensional single-mode waveguide arrays in bulk diamond through direct focused proton beam implantation

Abstract We demonstrate the feasibility of creating three-dimensional photonic devices through the realization of multi-level waveguides inside diamond by a series of systematic combined simulations grounded on Monte-Carlo statistics and Maxwell solver algorithms. Further, we have fabricated the counterparts of the multi-level waveguides buried in single crystalline diamond using a process based on several proton beam irradiation steps with different energies and fluences. On top of that, we draw a thorough comparison between the simulation results and the experimental observations, and find that they are in a good agreement with each other. Moreover, the simulation results also provide additional information such as the working fluence range of single-mode light (1550 nm) wave-guiding, the effective refractive index, and the polarization direction. The proof-of-concept of producing three-dimensional optical and photonic structures by direct focused proton beam implantation would open up a variety of new opportunities in designing and fabricating optical modulators, photonic components and quantum-computing related functional devices in bulk diamond, thus further promoting the development of three-dimensional diamond photonics.