Nanofabrication of high Q, transferable, diamond resonators

Advancement of diamond based photonic circuitry requires robust fabrication protocols of key components - including diamond resonators and cavities. Here, we present 1D (nanobeam) photonic crystal cavities generated from single crystal diamond membranes utilising a metallic tungsten layer as a restraining, conductive and removable hard mask. The use of tungsten instead of a more conventional silicon oxide layer enables good repeatability and reliability of the fabrication procedures. The process yields high quality diamond cavities with quality factors (Q-factors) approaching 1 × 104. Finally, we show that the cavities can be picked up and transferred onto a trenched substrate to realise fully suspended diamond cavities. Our fabrication process demonstrates the capability of diamond membranes as modular components for broader diamond based quantum photonic circuitry

Bottom up engineering of single crystal diamond membranes with germanium vacancy color centers

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. Color centers in diamond have garnered significant attention for applications in integrated quantum photonics. The availability of thin (~ hundred of nanometers) diamond membranes is paramount to achieve this goal. In this paper, we describe in detail a robust, reproducible and cost effective fabrication method that enables engineering high quality thin diamond membranes with uniform distribution of germanium vacancies employing microwave plasma chemical vapor deposition. We use a combination of different germanium precursors for homogeneous doping of the membranes to increase the probability of germanium incorporation into the diamond lattice. Our fabrication methodology can be further extended to implementation of other color centers in thin diamond membranes and be used for engineering quantum photonic devices

Photonic devices fabricated from (111)-oriented single crystal diamond

Diamond is a material of choice in the pursuit of integrated quantum photonic technologies. So far, the majority of photonic devices fabricated from diamond are made from (100)‐oriented crystals. In this work, we demonstrate a methodology for the fabrication of optically active membranes from (111)‐oriented diamond. We use a liftoff technique to generate membranes, followed by chemical vapor deposition of diamond in the presence of silicon to generate homogenous silicon vacancy color centers with emission properties that are superior to those in (100)‐oriented diamond. We further use the diamond membranes to fabricate microring resonators with quality factors exceeding ~ 3000. Supported by finite‐difference time‐domain calculations, we discuss the advantages of (111)‐oriented structures as building blocks for quantum nanophotonic devices

Bottom-Up Synthesis of Single Crystal Diamond Pyramids Containing Germanium Vacancy Centers

Diamond resonators containing color-centers are highly sought after for application in quantum technologies. Bottom-up approaches are promising for the generation of single-crystal diamond structures with purposely introduced color centers. Here the possibility of using a polycrystalline diamond to grow single-crystal diamond structures by employing a pattern growth method is demonstrated. For, the possible mechanism of growing a single-crystal structure with predefined shape and size from a polycrystalline substrate by controlling the growth condition is clarified. Then, by introducing germanium impurities during the growth, localized and enhanced emission from fabricated pyramid shaped single-crystal diamonds containing germanium vacancy (GeV) color centers is demonstrated. Finally, linewidth of ∼500 MHz at 4 K from a single GeV center in the pyramid shaped diamonds is measured. The method is an important step toward fabrication of 3D structures for integrated diamond photonics

Single Crystal Diamond Membranes and Photonic Resonators Containing Germanium Vacancy Color Centers

Copyright © 2018 American Chemical Society. Single crystal diamond membranes that host optically active emitters are highly attractive components for integrated quantum nanophotonics. In this work we demonstrate bottom-up synthesis of single crystal diamond membranes containing germanium vacancy (GeV) color centers. We employ a lift-off technique to generate the membranes and perform chemical vapor deposition in the presence of a germanium source to realize the in situ doping. Finally, we show that these membranes are suitable for engineering of photonic resonators such as microdisk cavities with quality factors of ∼1500. The robust and scalable approach to engineer single crystal diamond membranes containing emerging color centers is a promising pathway for the realization of diamond integrated quantum nanophotonic circuits on a chip