Nonlinear optical spectrum of diamond at femtosecond regime
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-10-24 |
| Journal | Scientific Reports |
| Authors | Juliana M. P. Almeida, Charlie Oncebay, Jonathas P. Siqueira, SĂ©rgio Ricardo Muniz, Leonardo De Boni |
| Institutions | Universidade de SĂŁo Paulo |
| Citations | 49 |
| Analysis | Full AI Review Included |
Technical Documentation and Analysis: Nonlinear Diamond Photonics
Section titled âTechnical Documentation and Analysis: Nonlinear Diamond PhotonicsâExecutive Summary
Section titled âExecutive SummaryâThis document analyzes the research on the third-order nonlinear optical properties of CVD diamond at femtosecond regimes, crucial for advancing integrated quantum and nonlinear optics platforms. 6CCVD provides the specialized material specifications required to replicate and scale this highly technical research.
- Core Achievement: First comprehensive measurement of the third-order nonlinear spectrum of diamond, spanning 0.83-4.77 eV (1500-260 nm), determining the two-photon absorption coefficient ($\beta$) and nonlinear refractive index (n2).
- Material Focus: Experiments relied on high-purity, type-IIa Single Crystal Diamond (SCD) grown by Chemical Vapor Deposition (CVD), specifically requiring ultra-low nitrogen (N < 5 ppb) and nitrogen vacancy (NV < 0.03 ppb) concentrations.
- Key Findings ($\beta$): The two-photon absorption coefficient ($\beta$) ranged from 0.07 to 0.23 cm/GW, increasing as photon energy approached the 5.54 eV bandgap.
- Key Findings (n2): The nonlinear refractive index (n2) varied from zero to $1.7 \times 10^{-19}$ m2/W, exhibiting positive values characteristic of ultrafast electronic nonlinearity.
- Ultrafast Response Confirmed: Optical Kerr Gate (OKG) measurements confirmed an instantaneous, pure electronic nonlinear response time of 130 fs, matching the laser pulse duration.
- Dominant Mechanism: Results demonstrate that phonon-assisted two-photon absorption is the dominant mechanism determining the third-order nonlinear susceptibility dispersion in indirect bandgap diamond.
- 6CCVD Value: 6CCVD specializes in delivering the ultra-high purity SCD plates (Ra &lt; 1 nm) and custom dimensions necessary for high-fidelity replication and future device integration based on these fundamental findings.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical material parameters and measured performance metrics extracted from the study, focusing on requirements for integrated photonics.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Material Type | Type-IIa Single Crystal Diamond (SCD) | N/A | CVD grown, highest purity optical grade |
| Sample Dimensions | $2 \times 2 \times 0.53$ | mmÂł | Single crystal plate used for Z-scan |
| Band Gap Energy ($E_{g}$) | 5.54 | eV | Fundamental material property of diamond |
| Nitrogen Impurities | &lt; 5 (usually &lt; 1) | ppb | Ultra-high purity requirement for optical studies |
| Nitrogen Vacancies (NV) | &lt; 0.03 | ppb | Low NV concentration confirmed by fluorescence |
| Polishing Roughness (Ra) | &lt; 5 | nm | On the {100} face |
| Z-scan Wavelength Range | 1500 to 260 | nm | Corresponds to 0.83-4.77 eV |
| Two-Photon Absorption ($\beta$) Range | 0.07 to 0.23 | cm/GW | Measured range as $E$ approached $E_{g}$ |
| Nonlinear Refractive Index ($n_{2}$) Range | 0 to $1.7 \times 10^{-19}$ | m2/W | Maximum observed positive value |
| Nonlinear Response Time | 130 | fs | Confirmed by Optical Kerr Gate (OKG) measurements |
| Excitation Regime | Femtosecond (120-150 fs) | Pulse Duration | Required to confirm pure electronic nonlinearity |
Key Methodologies
Section titled âKey MethodologiesâThe study successfully characterized the third-order nonlinear optical response of diamond using established ultrafast techniques tailored for wide spectral range analysis:
- Material Selection: A commercially sourced, high-purity, Type IIa SCD plate was used. The material purity (N < 5 ppb) and low defect concentration were confirmed via confocal fluorescence imaging.
- Laser System: Femtosecond pulses (150 fs, 775 nm, 1 kHz repetition rate) from a Ti:sapphire chirped pulse amplifier system were used to pump an Optical Parametric Amplifier (OPA). The OPA provided tunable 120 fs pulses from 2000 nm down to 260 nm.
- Z-Scan Technique: Open-aperture Z-scan measurements were conducted to determine the nonlinear absorption coefficient ($\beta$). Closed-aperture Z-scan measurements were used simultaneously (via a dual-arm setup) to determine the nonlinear refractive index ($n_{2}$).
- Nonlinear Absorption Detection: Two-Photon Absorption (2PA) was specifically detected only for photon energies $\ge$ 3.18 eV (390 nm), confirming its role as the dominant nonlinear absorption mechanism in this range.
- Optical Kerr Gate (OKG) Measurement: The time response of the nonlinearity was investigated using an OKG setup, employing strong pump and weak probe beams polarized at 45° relative angle. This confirmed the ultrafast (130 fs) pure electronic nature of the induced birefringence.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD is uniquely positioned to supply the advanced MPCVD diamond substrates required to not only reproduce this fundamental research but also scale these findings into next-generation integrated photonic and quantum devices.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate and extend this research on third-order nonlinearities, researchers require ultra-high purity Single Crystal Diamond (SCD) with superior optical performance and structural integrity.
- Material Recommendation: Optical Grade Single Crystal Diamond (SCD).
- This material matches the high-purity, Type-IIa specifications used in the paper (low N, low NV centers), essential for minimizing competing absorption mechanisms (e.g., cascade absorption by free carriers) that can distort true 2PA measurements.
- Bandgap Utilization: Given the measurements utilize photon energies near 4.77 eV (UV region), 6CCVDâs low-loss SCD ensures maximum transmission and minimized linear background absorption, vital for high signal-to-noise ratio in Z-scan setups.
Customization Potential
Section titled âCustomization PotentialâThe experimental findings lay the groundwork for integrated nonlinear optical platforms. 6CCVD offers extensive customization services required for device prototyping and fabrication.
| Requirement from Paper/Future Integration | 6CCVD Custom Capability | Benefit for Researchers |
|---|---|---|
| Purity & Quality | SCD with Ra &lt; 1 nm polishing | Exceeds the paperâs Ra &lt; 5 nm specification, providing atomically smooth surfaces crucial for minimizing scattering loss in integrated waveguides and resonators. |
| Custom Dimensions | Plates/wafers up to 125 mm (PCD); Substrates up to 10 mm thick | Enables scalability from benchtop experiments (like the $2 \times 2 \times 0.53$ mmÂł sample) to inch-size integrated photonics wafers. |
| Precise Thickness Control | SCD thickness from 0.1 ”m up to 500 ”m | Critical for optimizing light confinement and maximizing nonlinear interaction length in integrated diamond micro-resonators and waveguides. |
| Metalization for Integration | In-house capability for Au, Pt, Pd, Ti, W, Cu | Supports immediate post-growth processing for creating electrodes, ohmic contacts, or mirror layers necessary for high-speed quantum and nonlinear circuits (e.g., optical modulators or frequency conversion devices). |
Engineering Support
Section titled âEngineering SupportâThis research validates diamondâs ultrafast electronic response (130 fs) and high nonlinear coefficients, making it a powerful alternative to silicon for high-speed photonics.
- 6CCVDâs in-house PhD team provides specialized engineering consultation to assist clients transitioning from fundamental material characterization to integrated device fabrication. We offer expert support in material selection, orientation, and doping levels (e.g., selecting optimal SCD crystal orientation, such as the {100} face used in this study, and managing Boron Doping Density for electro-optic modulation projects).
- We specifically assist with material selection for similar Ultrafast Nonlinear Optics and Integrated Quantum Optics projects, ensuring material parameters (purity, defect control) are optimized for the intended application bandwidth and power regime.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We offer global shipping via DDU (default) or DDP (upon request).