Giant nonlinear optical effects induced by nitrogen-vacancy centers in diamond crystals

At a Glance

Metadata	Details
Publication Date	2019-10-22
Journal	Optics Express
Authors	Mari Motojima, Takara Suzuki, Hidemi Shigekawa, Yuta Kainuma, Toshu An
Citations	25
Analysis	Full AI Review Included

Technical Analysis and Material Sourcing Guide: NV Center Induced Nonlinear Optical Effects

This document analyzes the research paper “Giant nonlinear optical effects induced by nitrogen-vacancy centers in diamond crystals” (Motojima et al.) to highlight the technical requirements for replicating and advancing this research. It details how 6CCVD’s specialized MPCVD diamond capabilities align with the demands of high-purity quantum material studies and nonlinear photonics.

Executive Summary

The research successfully demonstrates that Nitrogen-Vacancy (NV) centers significantly enhance nonlinear optical effects (Optical Kerr Effect, OKE, and Two-Photon Absorption, TPA) in high-purity Single Crystal Diamond (SCD) using femtosecond laser pulses.

Core Achievement: Nonlinear optical effects, particularly OKE, are enhanced by the controlled introduction of NV centers in high-purity Type-IIa CVD diamond.
Dose Dependence: Signal enhancement is maximized at the highest N⁺ implantation dose investigated (1.0 x 10¹² N⁺/cm²).
Methodological Finding: Time-resolved reflectivity measurements (ΔR/R) revealed a signal enhancement several times greater than conventional transmission (Z-scan), confirming that the enhanced effects are highly localized to the surface region (30-40 nm).
Physical Mechanism: The dominant enhancement of OKE is attributed to “cascading OKE,” where the high density of NV centers near the surface breaks the natural inversion symmetry of the diamond lattice.
Material Requirement: The experiment required ultra-high purity, low-defect [100] orientation Type-IIa CVD diamond to ensure nonlinear effects originated specifically from NV-related electronic transitions rather than bulk impurities.
Application Relevance: These findings open new avenues for developing all-optical quantum sensing and computing technologies, including diamond waveguides, nanopillars, and ring resonators operating at telecom wavelengths.

Technical Specifications

The following table extracts critical hard data points and material parameters required for successful replication of the observed nonlinear optical phenomena.

Parameter	Value	Unit	Context
Substrate Material	Type-IIa [100] Orientation	N/A	High-Purity MPCVD Single Crystal Diamond (SCD)
Substrate Dimensions	3.0 x 3.0 x 0.3	mm	Thickness (L) = 300 µm
Initial Nitrogen Purity ([N])	< 1	ppm	Essential for defect control
Initial Boron Purity ([B])	< 0.05	ppm	Essential for defect control
Implantation Species	N⁺ (Nitrogen Ions)	30 keV	Used to create NV precursors
Low N⁺ Dose	2.0 x 10¹¹	N⁺/cm²	Exhibited significant enhancement
High N⁺ Dose	1.0 x 10¹²	N⁺/cm²	Achieved maximum OKE enhancement
NV Center Depth (TRIM)	30-40	nm	Localized near the surface
Annealing Temperature	900-1000	°C	Required for vacancy mobilization and NV formation
Annealing Atmosphere	Argon	N/A	1 hour duration
Laser Pulse Duration (τ_p)	≈40	fs	Required for ultrafast nonlinear effects
Laser Wavelength (λ)	≈800	nm	Near-infrared excitation
Max Non-linear Refraction (n₂)	24.2 ± 0.50 x 10^-20	m²/W	Heavily implanted sample (1.0 x 10¹² N⁺/cm², ΔR/R measurement)
Max Non-linear Absorption (β)	1.75 ± 0.09 x 10^-1	cm/GW	Mid implanted sample (2.0 x 10¹¹ N⁺/cm², ΔR/R measurement)

Key Methodologies

The experiment combined precise material synthesis and defect engineering with specialized ultrafast optical measurements to isolate surface-specific nonlinear phenomena.

Substrate Fabrication: High-purity [100] orientation diamond crystals were grown using the MPCVD method (Element Six Type-IIa equivalent), ensuring extremely low initial nitrogen and boron content ([N] < 1 ppm, [B] < 0.05 ppm).
NV Center Creation (Implantation): Diamond samples were implanted with 30 keV Nitrogen ions (N⁺) at controlled doses (2.0 x 10¹¹ N⁺/cm² and 1.0 x 10¹² N⁺/cm²) to generate vacancies and localized defects 30-40 nm below the surface.
NV Center Activation (Annealing): Post-implantation annealing was performed at 900-1000 °C for 1 hour in an Argon atmosphere, allowing vacancies to diffuse and trap N atoms, thereby forming NV centers (estimated production efficiency of ≈1%).
Z-Scan Measurement (Bulk/Transmission): A closed-aperture Z-scan setup utilized a regenerative amplifier system (40 fs, 800 nm pulses) to measure nonlinear refraction (OKE) and absorption (TPA) through changes in transmittance.
Pump-Probe Measurement (Surface/Reflectivity): A reflection-type femtosecond pump-probe system was employed to measure time-resolved transient reflectivity (ΔR/R) at room temperature, providing sensitivity primarily to nonlinear effects localized near the surface.
Data Fitting: Experimental data was fitted using Z-scan models (Eq. 2) and transient reflectivity models (Eq. 3 and 4) to derive the third-order nonlinear coefficients, $n_{2}$ and $\beta$.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the advanced diamond materials required to replicate or extend this groundbreaking research in quantum nonlinear optics. Our core MPCVD capabilities guarantee the high purity and structural control essential for controlling NV defects.

Applicable Materials

To achieve the controlled, defect-driven nonlinear enhancement demonstrated in this paper, researchers require the highest quality precursor material.

Material: Optical Grade Single Crystal Diamond (SCD)
- Specification Alignment: Our SCD wafers are the functional equivalent of the high-purity Type-IIa material used in this study. We guarantee extremely low native nitrogen and boron concentrations, which is critical for ensuring that any subsequent nonlinear phenomena are solely dependent on the engineered NV centers, not bulk impurities.
- Crystal Orientation: Standard [100] orientation SCD substrates are available, matching the material used for reliable NV formation.
Alternative Materials (Extension):
- High-Purity Polycrystalline Diamond (PCD): While SCD was preferred for symmetry control, high-purity PCD (up to 125mm size) may be investigated for large-area quantum sensing arrays or for studies where grain boundary effects on nonlinear cascading OKE are of interest.

Customization Potential

The experimental setup outlined requires specific dimensions and precise surface preparation capabilities offered by 6CCVD.

Requirement in Paper	6CCVD Customization Capability
Substrate Dimensions (3x3x0.3 mm)	Custom Dimensions and Thickness Control: We provide SCD plates up to 125mm (PCD) and offer thickness control from 0.1 µm up to 500 µm, perfectly accommodating the required 300 µm thickness. Precision dicing/laser cutting services are available.
Surface Sensitivity (ΔR/R method)	Ultra-Low Roughness Polishing: Our standard SCD polishing achieves roughness $R_{a}$ < 1 nm, ensuring an atomically smooth surface ideal for surface-sensitive reflection measurements and minimizing scattering losses in photonic integration.
Photonic Integration (Waveguides, Nanopillars)	Custom Metalization and Structuring: For future integration into quantum photonic devices (as suggested in the paper’s conclusion, Refs [39-41]), 6CCVD offers in-house deposition of thin films including Au, Pt, Ti, W, and Pd. We support engineers designing electrodes or optical routing structures.
Defect Control (NV Precursor Supply)	Controlled Nitrogen Doping: While this paper used implantation, 6CCVD can supply SCD with precisely controlled, low levels of in-situ nitrogen (N) doping during MPCVD growth, acting as a precursor for bulk NV creation or customized BDD materials.
Global Access	Seamless Global Logistics: We ensure reliable global shipping (DDU default, DDP available) of sensitive, high-value diamond materials directly to your laboratory.

Engineering Support

6CCVD’s in-house team of material scientists and PhD engineers are experts in MPCVD diamond synthesis and post-processing requirements for quantum applications.

Material Selection for Nonlinear Quantum Sensing: Our engineering staff can assist researchers in optimizing the precursor SCD purity and thickness based on target NV density and preferred creation method (implantation vs. in-situ doping).
Post-Processing Consultation: We offer advisory support regarding optimal annealing parameters (temperature and atmosphere control) necessary to maximize NV creation efficiency while maintaining the integrity of the high-purity substrate.
Integration Support: Assistance is provided in defining specifications for surface finishing and metal contacts necessary for complex quantum devices leveraging OKE or TPA effects in diamond photonics.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

We investigate the effect of nitrogen-vacancy (NV) centers in single crystal diamond on nonlinear optical effects using 40 fs femtosecond laser pulses. The near-infrared femtosecond pulses allow us to study purely nonlinear optical effects, such as optical Kerr effect (OKE) and two-photon absorption (TPA), related to unique optical transitions by electronic structures with NV centers. It is found that both nonlinear optical effects are enhanced by the introduction of NV centers in the N + dose levels of 2.0×10 11 and 1.0×10 12 N +/cm 2. In particular, our data demonstrate that the OKE signal is strongly enhanced for the heavily implanted type-IIa diamond. We suggest that the strong enhancement of the OKE is possibly originated from cascading OKE, where the high-density NV centers effectively break the inversion symmetry near the surface region of diamond.

Tech Support

Original Source

DOI: https://doi.org/10.1364/oe.27.032217