Laser-Inscribed Diamond Waveguide Resonantly Coupled to Diamond Microsphere

TL;DR

This paper demonstrates an integrated diamond photonic circuit combining a femtosecond-laser-written waveguide with a microsphere, achieving high-quality whispering-gallery modes for potential sensing and filtering applications.

Contribution

It introduces a novel all-diamond photonic circuit with a laser-inscribed waveguide coupled to a microsphere, enabling high-Q resonances in integrated diamond photonics.

Findings

Achieved whispering-gallery modes with 0.33 nm spacing

High-quality factors of 10^5 in the resonances

Demonstrated potential for sensing and filtering applications

Abstract

An all-diamond photonic circuit was implemented by integrating a diamond microsphere with a femtosecond-laser-written bulk diamond waveguide. The near surface waveguide was fabricated by exploiting the Type II fabrication method to achieve stress-induced waveguiding. Transverse electrically and transverse magnetically polarized light from a tunable laser operating in the near-infrared region was injected into the diamond waveguide, which when coupled to the diamond microsphere showed whispering-gallery modes with a spacing of 0.33 nm and high-quality factors of 105. By carefully engineering these high-quality factor resonances, and further exploiting the properties of existing nitrogen-vacancy centers in diamond microspheres and diamond waveguides in such configurations, it should be possible to realize filtering, sensing and nonlinear optical applications in integrated diamond photonics.