Laser micromachining of diamond - A viable photonic and optofluidic platform
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | EPJ Web of Conferences |
| Authors | Ottavia Jedrkiewicz, Akhil Kuriakose, Argyri N. Giakoumaki, Giulio Coccia, Monica Bollani |
| Institutions | Politecnico di Milano, Istituto di Fotonica e Nanotecnologie |
| Citations | 1 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research details the successful application of ultrafast laser writing techniques to fabricate integrated photonic, electrical, and microfluidic components within Chemical Vapor Deposition (CVD) diamond, establishing it as a robust platform for advanced sensing technologies.
- Integrated Platform: Demonstrated the fabrication of multiple functional building blocksâNV centers, optical waveguides, graphitic wires, microchannels, and through-holesâwithin a single diamond substrate.
- Quantum Sensing Foundation: NV centers (Nitrogen-Vacancy) were generated and integrated into waveguides, forming the basis for prototype quantum-based electric and magnetic field sensors.
- Electrical Control: Tailored graphitic wires were laser-written using Bessel beams (2 ”J to 11 ”J pulse energy) to enable electrical interfacing and control of quantum emitters within the diamond.
- High-Quality Photonics: Low-loss optical waveguides (loss < 0.5 dB/cm at 635 nm) were fabricated, capable of guiding light over 50 mm lengths.
- Microfluidic Integration: Developed techniques for creating deep surface microchannels (V-shaped or square) and through-holes in 500 ”m thick diamond, crucial for lab-on-chip (LOC) applications.
- Core Methodology: The technique relies on tailoring the laser processing (single pass Bessel, multiple pass Gaussian) to achieve specific material modifications (photonic, graphitic, or ablative).
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Thickness (Tested) | 500 | ”m | Thickness of CVD diamond sample used for graphitic wires and through-holes. |
| Waveguide Length (Fabricated) | 50 | mm | Length of integrated optical waveguides. |
| Waveguide Loss (635 nm) | < 0.5 | dB/cm | Measured propagation loss at the near-IR wavelength. |
| Waveguide Mode Field Diameter (MFD) | 10 | ”m | MFD measured at 635 nm wavelength. |
| Laser Pulse Energy (Graphitic Wires) | 2 to 11 | ”J | Range of pulse energies used for Bessel beam writing. |
| Microchannel Shape (Single Pass) | V-shaped | N/A | Result of single pass Bessel beam ablation (high aspect ratio). |
| Microchannel Shape (Multiple Pass) | Regular square | N/A | Result of multiple pass Gaussian writing technique. |
| Microchannel Application | N/A | N/A | Suitable for microfluidics and biosensing applications. |
| Through-Hole Technique | Bessel + Trepanning | N/A | Used for micro-drilling through thick diamond samples. |
Key Methodologies
Section titled âKey MethodologiesâThe fabrication relies entirely on the ultrafast laser writing technique, utilizing different beam profiles and processing parameters to achieve distinct material modifications within the diamond lattice.
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NV Center Generation:
- Ultrafast laser pulses are used to create vacancies and incorporate nitrogen atoms, forming NV centers (quantum emitters).
- The concentration of laser-formed NVs can be precisely tuned by controlling the laser parameters.
- Ensemble NVs were written and integrated within waveguides to increase measurement sensitivity.
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Photonic Waveguide Fabrication:
- Laser writing is used to create refractive index modifications, forming optical waveguides (50 mm long) for efficient light delivery and collection.
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Graphitic Wire Generation (Electrical Interfacing):
- Beam Type: Bessel beams were employed.
- Process: Laser writing was performed throughout the 500 ”m thick CVD diamond sample without requiring sample translation.
- Purpose: To create conductive graphitic modifications for electrical control of quantum emitters (charge state and stimulated emission).
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Surface Microchannel Fabrication (Ablation):
- Deep Ablation: Used for creating surface microchannels for microfluidics.
- Technique 1 (High Aspect Ratio): Single pass writing using Bessel beams resulted in deep, V-shaped trenches with a micrometer-sized central channel.
- Technique 2 (Standard Channels): Multiple pass writing using a standard technique (likely Gaussian beams) resulted in regular square-shaped channels.
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Through-Hole Microfabrication:
- Process: A micro-drilling method combining Bessel machining with a trepanning-like technique.
- Integration: These through-holes allow for the integration of surface microchannels with internal structures, enabling complete lab-on-chip prototypes (Fig. 4).
Commercial Applications
Section titled âCommercial ApplicationsâThe integrated diamond platform developed using ultrafast laser writing is highly relevant for industries requiring robust, high-performance quantum and microfluidic devices.
- Quantum Sensing and Metrology:
- Development of prototype quantum-based electric field sensors.
- Development of prototype quantum-based magnetic field sensors (utilizing NV centers).
- Integrated Photonics:
- Fabrication of robust, low-loss optical networks and waveguides for quantum communication and on-chip light manipulation.
- Microfluidic and Biosensing Devices:
- Creation of diamond lab-on-chip (LOC) prototypes, leveraging diamondâs chemical inertness and biocompatibility.
- Applications in biosensing due to the ability to create precise, square-shaped microchannels.
- Advanced Electrical Interfacing:
- Use of laser-written graphitic wires to provide electrical control and readout for quantum devices operating in harsh environments.
View Original Abstract
We describe how the ultrafast laser micromachining technique applied with different writing methods can be used for the creation of various building blocks essential for the realization of a photonic and optofluidic diamond platform. Waveguides, NV centers, conductive wires, microchannels and microholes can be obtained thanks to laser microfabrication with suitable pulse parameters, making use not only of standard Gaussian laser beams but also of non-diffracting Bessel beams, the latter especially in all those cases where single pass high aspect-ratio microstructures or ablated areas are needed.