Polycrystalline diamond photonic waveguides realized by femtosecond laser lithography

Hanafi H, Kroesen S, Lewes-Malandrakis G, Nebel C, Pernice W, and Denz C

Abstract

In recent years, the perception of diamond has changed from it being a pure gemstoneto a universal high-tech material. In the field of photonics, an increased interest is emerging due toits outstanding optical properties, such as its high refractive index, a spectrally wide transmissionwindow, and high Raman coefficient. Furthermore, the capability to host color defects for roomtemperature single photon generation makes diamond an attractive platformfor quantum photonics.Known as nature's hardest material, the fabrication and handling of crystalline diamond forintegrated optics remains challenging. Here, we report on the fabrication of three-dimensionalType III depressed cladding waveguides in polycrystalline diamond substrates by direct laserwriting. Single mode waveguiding is demonstrated in the near-infrared telecommunicationC-band. We believe that this enables the fabrication of three-dimensional large-scale photoniccircuits, which are essential for advanced classical and quantum diamond photonics.