Laser-induced luminescent centers in diamond - influence of exposure and duration of short laser pulses
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | Оптика и спектроскопия |
| Authors | П. А. Данилов, S. I. Kudryashov, A. O. Levchenko, E. A. Oleynichuk, O. E. Koval’chuk |
| Institutions | VNIIGIS, P.N. Lebedev Physical Institute of the Russian Academy of Sciences |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This study investigates the precise formation of luminescent point defects, specifically Nitrogen Vacancy (NV) centers, deep within natural IaA-type diamond using ultrashort laser pulses (USLP) in the visible range (515 nm).
- Core Achievement: Successful, non-destructive volume writing of negatively charged NV centers (NV-) at a depth of ~200 µm without inducing visible damage or graphitization traces.
- Defect Confirmation: Confocal Raman spectroscopy confirmed the formation of NV centers, characterized by a strong luminescence peak around 640 nm.
- Optimal Processing: A pulse duration of 1.0 ps yielded the highest luminescence amplitude (NV center concentration) compared to 0.3 ps and 2.4 ps durations.
- Kinetics Established: The luminescence yield of the formed NV centers exhibits a linear dependence on the total exposure time (number of pulses) across tested energies (up to 600 nJ).
- Methodology: Utilized 515 nm USLP (100 kHz repetition rate) with energies ranging from 60 nJ to 600 nJ, demonstrating high contrast and stability of the formed luminescent marks.
- Value Proposition: This technique is highly promising for creating stable, high-contrast, “invisible” micro-marks and for fabricating solid-state quantum devices within diamond.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Material | IaA-type Natural Diamond | - | Colorless, transparent cube (~4 mm side) |
| Processing Wavelength | 515 | nm | Second Harmonic (SH) of Ytterbium fiber laser |
| Pulse Duration (Tested) | 0.3, 1.0, 2.4 | ps | Varied using built-in compressor |
| Repetition Rate | 100 | kHz | Constant during processing |
| Pulse Energy (Tested) | 60 to 600 | nJ | Range used for defect matrix formation |
| Maximum Pulse Energy (System) | 3.6 | µJ | Before optical scheme losses |
| Writing Depth | ~200 | µm | Volume writing location |
| Focal Spot Size (R1/e) | 2.2 ± 0.2 | µm | Measured in air |
| Numerical Aperture (NA) | 0.25 | - | Micro-objective (OB1) |
| Exposure Time (Range) | 30 to 360 | s | Corresponds to total pulse count |
| Total Pulses per Point (N) | (3-36) * 106 | Pulses | Calculated from exposure time |
| Defect Formed | Negatively Charged NV Center | NV- | Confirmed by spectroscopy |
| Optimal Pulse Duration | 1.0 | ps | Yielded maximum luminescence amplitude |
| Luminescence Peak (Observed) | ~640 | nm | Associated with NV centers |
| Excitation Wavelength (Analysis) | 532 | nm | Continuous pump laser for confocal spectroscopy |
| Diamond Raman Shift | 1331 | cm-1 | Characteristic diamond line |
Key Methodologies
Section titled “Key Methodologies”The experiment utilized a direct laser writing setup combined with advanced confocal spectroscopy for visualization and analysis.
- Material Preparation: IaA-type natural diamond was pre-characterized using spectrophotometry (200-1100 nm range), confirming the presence of N3 centers (absorption peak at 415 nm).
- Laser Setup and Focusing: The 515 nm second harmonic (SH) of a 100 kHz ytterbium fiber laser was used. The pulse duration was varied between 0.3 ps and 2.4 ps. Radiation was focused to a depth of ~200 µm using a micro-objective (NA = 0.25).
- Defect Matrix Writing: Point defects were written in a matrix pattern by varying two primary parameters:
- Pulse Energy (60 nJ to 600 nJ).
- Exposure Time (30 s to 360 s), corresponding to (3-36) * 106 pulses per point.
- Initial Structural Analysis: Optical microscopy was performed on the surface and volume of the irradiated areas to confirm the absence of graphitization or visible structural damage.
- Luminescence and Raman Analysis: A 3D scanning confocal Raman microscope (532 nm pump laser) was used to generate 2D fluorescent images and record luminescence spectra of the formed defects.
- Yield Quantification: The luminescence yield was quantified based on the amplitude maximum (~640 nm peak) of the difference spectra (defect minus background). This yield was plotted against the number of pulses for various durations (0.3, 1.0, 2.4 ps) and energies (150 nJ, 300 nJ) to determine formation kinetics.
Commercial Applications
Section titled “Commercial Applications”The precise, non-destructive formation of NV centers deep within diamond volume has significant implications for several high-tech sectors:
- Quantum Technologies: NV centers are critical solid-state qubits. This method enables the deterministic fabrication of NV center arrays for quantum computing architectures and quantum memory devices.
- Quantum Sensing: NV centers are highly sensitive sensors for magnetic fields, electric fields, and temperature. The ability to write these centers deep inside the material allows for robust, integrated sensor fabrication.
- High-Security Micro-marking: The technique provides a method for “invisible” laser micromarking of high-value diamonds (gems, industrial tools) for anti-counterfeiting and traceability, as the marks are luminescent but do not involve visible graphitization damage.
- Advanced Photonics: Creating stable, optically active point defects can be used for fabricating integrated optical components, such as waveguides and single-photon sources, within diamond substrates.
- Optical Data Storage: Utilizing the stable nature of the formed defects for high-density, three-dimensional optical data storage within dielectric crystals.
View Original Abstract
The optical properties of point luminescent centers formed in the volume IaA-type natural diamond under the action of ultrashort laser pulses in the visible range (515 nm) with durations of 0.3-2.4 ps were investigated. The analysis using confocal Raman spectroscopy demonstrates the formation of nitrogen vacancy centers (NV) and there are no graphitization traces in processing areas. The luminescence amplitude of NV centers depends linearly on the exposure time at different durations of ultrashort laser pulses. Keywords: ultrashort laser pulses, luminescence, luminescent centers in diamond, NV centers.