Diamond optomechanical crystals
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-11-17 |
| Journal | Optica |
| Authors | Michael J. Burek, Justin Cohen, SeĂĄn M. Meenehan, Nayera El-Sawah, Cleaven Chia |
| Institutions | Harvard University, University of Waterloo |
| Citations | 157 |
| Analysis | Full AI Review Included |
DIAMOND OPTOMECHANICAL CRYSTALS: Material Requirements & 6CCVD Solutions
Section titled âDIAMOND OPTOMECHANICAL CRYSTALS: Material Requirements & 6CCVD SolutionsâExecutive Summary
Section titled âExecutive SummaryâThis documentation analyzes the key findings of research into high-performance diamond Optomechanical Crystals (OMCs), highlighting the necessary material specifications and connecting them directly to 6CCVDâs advanced CVD diamond offerings for quantum and optomechanical applications.
- Platform Validation: Demonstrates Single-Crystal Diamond (SCD) OMCs operating in the resolved-sideband regime, establishing diamond as a superior platform for high-frequency quantum transduction.
- Record Cooperativity: Achieved record room-temperature optomechanical cooperativity (C â 20) in diamond, necessary for strong mechanical driving and effective laser cooling.
- Ultra-High Q-Factor: Realized exceptional mechanical quality factors (Qm) up to Qm ~ 7700 at 9.45 GHz, corresponding to an f·Q product of ~7.3 x 1013 Hzâamong the highest reported for monolithic room-temperature diamond oscillators.
- High Purity Requirement: The successful fabrication relied on ultra-high purity MPCVD SCD substrates (nitrogen content ~1 ppb N) to minimize optical absorption and thermal dissipation effects.
- Key Functionality: The devices co-localize 200 THz photons (telecom band) and 5-10 GHz acoustic phonons, enabling critical phenomena like Optomechanically Induced Transparency (OMIT) and phonon lasing.
- Quantum Interface Potential: The system is explicitly designed to interface with diamond color centers (NV, SiV) for realizing hybrid quantum systems leveraging phonons as quantum information carriers.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Optical Resonance (λ0) | 1529.2 | nm | Telecom C-Band (Ï0/2Ï ~ 196 THz) |
| Intrinsic Optical Q-factor (Qi) | 2.70 x 105 | Dimensionless | High quality SCD optical cavity |
| Optical Linewidth (Îș/2Ï) | 1.114 | GHz | Total cavity decay rate |
| Mechanical Resonance (Flapping Mode) | 5.52 | GHz | Acoustic flapping mode |
| Mechanical Q-factor (Flapping Mode) | ~4100 | Dimensionless | Measured at room temperature |
| Mechanical Resonance (Swelling Mode) | 9.45 | GHz | Acoustic swelling mode |
| Mechanical Q-factor (Swelling Mode) | ~7700 | Dimensionless | Highest Qm achieved, room temperature |
| Mechanical f·Q Product | 7.3 x 1013 | Hz | Figure of merit for mechanical resonators |
| Single-Photon Coupling (g0/2Ï) | 118 ± 6 | kHz | Experimental estimate (Flapping Mode) |
| Maximum Cooperativity (Cmax) | ~20 | Dimensionless | Achieved with EDFA input power |
| Intracavity Photon Capacity (nc,max) | ~162,000 | Photons | Inferred maximum capacity at Cmax |
| Diamond Purity (N content) | ~1 | ppb | Required for low dissipation (via EPR) |
| Substrate Roughness (Initial) | < 5 | nm RMS | Commercial polishing specification |
| Substrate Roughness (Final Prep) | < 1 | nm RMS | Achieved via pre-fabrication plasma etch |
Key Methodologies
Section titled âKey MethodologiesâThe Diamond OMC fabrication relies on extreme material purity and sophisticated nanoscale etching techniques to create the suspended nanobeam structures:
- High-Purity Material Input: Use of synthetic single-crystal diamond (SCD) synthesized via MPCVD, specifically engineered for ultra-low nitrogen content (~1 ppb N) to minimize optically active defects and absorption.
- Crystallographic Alignment: Diamond substrates oriented with a (100) surface normal and nanobeam axis aligned to the in-plane [110] crystallographic direction to enhance robustness against fabrication imperfections.
- Advanced Surface Preparation: A two-step ICP-RIE pre-etch (using Ar, Cl2, O2 plasma sequences) was performed to reduce substrate surface roughness to below 1 nm RMS and relieve strain from mechanical polishing.
- Patterning: Electron Beam Lithography (EBL) used with a silica etch mask (HSQ resist) defined the 1D photonic crystal cavity structure (elliptical air holes) with defect regions.
- Angled-Etching Fabrication: Anisotropic oxygen-based plasma etching was performed at an oblique angle (using a specialized Faraday cage) to undercut and suspend the nanobeam structures, resulting in the required triangular cross-section.
- Thermal Annealing: Post-fabrication annealing at 450 °C in a high-purity oxygen environment for 8 hours was critical for cleaning and stabilizing the devices prior to spectroscopy.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis demanding research requires materials and processing capabilities that are core strengths of 6CCVD. We offer the specific high-purity materials and customization services needed to replicate, scale, and extend this work toward commercial quantum devices.
Applicable Materials
Section titled âApplicable MaterialsâThe foundation of this research is ultra-high purity single-crystal diamond (SCD) for its superior mechanical, thermal, and optical properties.
| Material | Specification | 6CCVD Capability & Advantage |
|---|---|---|
| Optical Grade SCD | High purity (low ppb N), necessary for large intracavity photon capacity and low optical loss in the telecom band. | 6CCVD provides SCD with exceptional purity, controlled nitrogen/impurity levels for optimal optical transmission and low mechanical damping. Thicknesses available from 0.1 ”m up to 500 ”m. |
| Quantum Grade SCD | Required for future integration of high-coherence color centers (NV/SiV) mentioned in the conclusions. | 6CCVD can supply SCD substrates optimized for targeted defect incorporation (e.g., tailored vacancy concentration or implantation sites). |
| Boron-Doped Diamond (BDD) | (Future consideration) For applications requiring electrical conductivity or specific thermal properties in hybrid systems. | 6CCVD offers customizable BDD films and substrates with precise doping concentrations. |
Customization Potential
Section titled âCustomization PotentialâThe experimental success hinged on precise geometry, crystallographic alignment, and ultra-smooth surfaces. 6CCVD excels in providing these exact specifications.
| Requirement from Paper | 6CCVD Customization Service | Value Proposition |
|---|---|---|
| Substrate Dimensions & Thickness | Custom plates/wafers up to 125 mm (PCD equivalent size) and SCD thicknesses up to 500 ”m. | We provide large-format, thick SCD wafers essential for supporting high-aspect ratio free-standing nanostructures. |
| Surface Finish (Ra < 1 nm) | SCD Polishing Service: Guaranteed Ra < 1 nm (Atomic smoothness). | Our polishing exceeds the experimentâs initial requirement (< 5 nm), reducing surface scattering and minimizing strain precursors prior to the final ICP-RIE clean. |
| Crystallographic Orientation | Custom laser cutting and machining services aligned precisely to the [110] or [100] crystallographic directions. | Ensures optimal device alignment necessary for precise photo-elastic coupling calculations and robust device symmetry against etching imperfections. |
| Metalization Integration | Custom deposition of Au, Pt, Pd, Ti, W, Cu layers. | Essential for creating contacts, bonding pads, or integrating superconducting circuits (as required for quantum readout, ref. 6). |
Engineering Support
Section titled âEngineering SupportâThe realization of high-performance diamond OMCs requires specialized knowledge spanning material science, nanofabrication, and quantum physics.
6CCVDâs in-house PhD team specializes in the physics and fabrication of CVD diamond for advanced applications. We can assist engineers and researchers with:
- Material Selection: Advising on optimal purity, thickness, and crystallographic orientation for quantum optomechanical or color center integration projects.
- Thermal/Strain Management: Consultation on minimizing thermo-optic bistability and managing intrinsic strain, critical factors that limited the maximum observed cooperativity in the reported experiments.
- Advanced Polishing: Ensuring the starting substrates meet or exceed the roughness specification (< 1 nm Ra) necessary for high-Q optical cavities operating at 200 THz.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We ship globally (DDU default, DDP available).
View Original Abstract
Cavity-optomechanical systems realized in single-crystal diamond are poised to benefit from its extraordinary material properties, including low mechanical dissipation and a wide optical transparency window. Diamond is also rich in optically active defects, such as the nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers, which behave as atom-like systems in the solid state. Predictions and observations of coherent coupling of the NV electronic spin to phonons via lattice strain have motivated the development of diamond nanomechanical devices aimed at the realization of hybrid quantum systems in which phonons provide an interface with diamond spins. In this work, we demonstrate diamond optomechanical crystals (OMCs), a device platform to enable such applications, wherein the co-localization of âŒ200 THz photons and few to 10 GHz phonons in a quasi-periodic diamond nanostructure leads to coupling of an optical cavity field to a mechanical mode via radiation pressure. In contrast to other material systems, diamond OMCs operating in the resolved-sideband regime possess large intracavity photon capacities (>10^5) and sufficient optomechanical coupling rates to reach a cooperativity of âŒ20 at room temperature, allowing for the observation of optomechanically induced transparency and the realization of large-amplitude optomechanical self-oscillations.