An ultrafast diamond nonlinear photonic sensor

At a Glance

Metadata	Details
Publication Date	2025-09-25
Journal	Nature Communications
Authors	Daisuke Sato, Junjie Guo, Takuto Ichikawa, Dwi Prananto, Toshu An
Institutions	University of Tsukuba, Japan Advanced Institute of Science and Technology
Analysis	Full AI Review Included

Ultrafast Diamond Nonlinear Photonic Sensor: 6CCVD Technical Analysis

This document analyzes the requirements and achievements detailed in the research paper, “An ultrafast diamond nonlinear photonic sensor,” and maps them directly to the advanced Single Crystal Diamond (SCD) and fabrication capabilities offered by 6CCVD.

Executive Summary

The research successfully demonstrates a novel diamond-based sensor achieving unprecedented spatio-temporal resolution for electric field mapping, opening new avenues for nano-material characterization.

Core Achievement: Development of an ultrafast diamond nonlinear photonic sensor utilizing shallow Nitrogen-Vacancy (NV) centers in a nanotip geometry.
Resolution Breakthrough: Achieved temporal resolution of ≤100 fs and spatial resolution of ≤500 nm (with projected potential down to ~10 nm).
Sensing Mechanism: The sensor operates via the Pockels electro-optic (EO) effect, which is enabled by the breaking of spatial inversion symmetry (χ⁽²⁾ ≠ 0) due to the presence of NV defects.
Material Foundation: The probe was fabricated from electronic-grade, (100)-oriented Single Crystal Diamond (SCD) with ultra-low nitrogen impurity (<5 ppb).
Fabrication Method: NV centers were generated via precise 30 keV ¹⁴N⁺ ion implantation (~40 nm depth), followed by high-precision laser cutting and Focused Ion Beam (FIB) milling to create the nanotip.
Application Demonstrated: Successful measurement of ultrafast carrier screening dynamics and local electric fields on prototypical semiconductors (n-GaAs) and 2D materials (WSe₂).

Technical Specifications

The following hard data points were extracted from the experimental results and methodology:

Parameter	Value	Unit	Context
Diamond Material Grade	Electronic-Grade SCD	N/A	CVD-grown, ultra-low impurity
Crystal Orientation	(100)	N/A	Substrate orientation
Initial Nitrogen Impurity	<5	ppb	Required for high-quality NV centers
NV Center Generation	¹⁴N⁺ Ion Implantation	N/A	Followed by 900 °C annealing
Implantation Energy	30	keV	Used to control NV depth
Implantation Depth (Estimated)	~40	nm	Deduced from SRIM simulation
Annealing Temperature	900	°C	For 1 hour in Ar atmosphere
Pump Laser Pulse Length	≤10	fs	Ti: sapphire oscillator
Pump Laser Wavelength	660 to 940	nm	Near-infrared range (1.88 to 1.32 eV)
Temporal Resolution (Achieved)	≤100	fs	FWHM of shortest EO response
Spatial Resolution (Achieved)	≤500	nm	Limited by NV tip apex diameter (~800 nm)
EO Signal Amplitude (Local)	~1/42	N/A	Ratio compared to macroscopic n-GaAs measurement
Estimated Sensitivity (n-GaAs)	~1 x 10^-2	V µm^-1 Hz^-1/2	Based on 1s measurement time at 10 Hz

Key Methodologies

The experimental success relies on precise material engineering and integration of advanced microscopy techniques:

High-Purity Material Selection: Utilization of (100)-oriented, electronic-grade CVD Single Crystal Diamond (SCD) with nitrogen impurity levels strictly controlled to below 5 ppb.
Shallow NV Layer Creation: Precise generation of NV centers via ¹⁴N⁺ ion implantation at 30 keV, targeting a shallow depth of approximately 40 nm from the surface.
Thermal Annealing: Post-implantation annealing performed at 900 °C for 1 hour in an Argon atmosphere to promote vacancy mobility and NV center formation.
Nanoprobe Fabrication: The SCD was shaped using two high-precision techniques:
- Initial shaping via laser cutting.
- Final tip refinement via Gallium ion (Ga⁺) Focused Ion Beam (FIB) milling to achieve the required nanotip geometry.
AFM Integration: The diamond NV probe was attached to a self-sensing cantilever, enabling Atomic Force Microscopy (AFM) operation in “pin-point mode” (vertical approach/retraction) to maintain quasi-zero distance (0.1-0.3 nm) between the tip and sample surface.
Ultrafast Pump-Probe Setup: Implementation of a reflective electro-optic (EO) sampling scheme using a 10-fs pulsed Ti: sapphire laser, optimized with a reflective (Schwarzschild) objective lens to minimize dispersion and achieve ultrafast time resolution.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the foundational materials and custom fabrication services required to replicate, scale, and advance this cutting-edge research in ultrafast diamond quantum sensing.

Applicable Materials for Replication and Extension

Research Requirement	6CCVD Material Solution	Technical Specification Alignment
Electronic-Grade SCD	Optical Grade Single Crystal Diamond (SCD)	Guaranteed ultra-low nitrogen content (<5 ppb) essential for high-coherence NV centers and minimal background noise. Available in (100) orientation.
Substrate Thickness	SCD Wafers and Substrates	SCD thickness from 0.1 µm up to 500 µm, and substrates up to 10 mm thick, providing robust material for nanotip fabrication.
Surface Quality	Precision Polished SCD	Standard polishing achieves Ra < 1 nm, ensuring an atomically smooth surface critical for precise, shallow ion implantation (30 keV, ~40 nm depth).
Future Power Applications	Boron-Doped Diamond (BDD)	For extending sensing to power device materials (e.g., SiC) or high-conductivity applications, 6CCVD offers BDD with tunable doping levels.

Customization Potential for Advanced Probes

The fabrication of the diamond NV nanotip requires specialized shaping and integration capabilities, which 6CCVD provides:

Custom Dimensions and Shaping: 6CCVD offers custom laser cutting and shaping services to prepare the SCD substrates for subsequent FIB milling, ensuring the precise geometry required for cantilever attachment and nanotip formation.
Large-Area Polycrystalline Diamond (PCD): While the paper uses SCD, 6CCVD can provide large-area PCD plates (up to 125 mm diameter) with Ra < 5 nm for scaling up non-quantum-critical applications or for use as robust, large-area heat spreaders in integrated systems.
Metalization Services: The paper notes that conventional NV sensing requires metallic contacts for external microwaves. 6CCVD offers in-house metalization (Au, Pt, Pd, Ti, W, Cu) for integrating microwave strip lines or ohmic contacts directly onto the diamond surface, facilitating the development of integrated quantum circuits.

Engineering Support

6CCVD’s in-house team of PhD material scientists and engineers specializes in optimizing CVD diamond properties for quantum and electro-optic applications.

Ion Implantation Consultation: We provide expert consultation on material preparation (orientation, surface termination, polishing) necessary to maximize the yield and control the depth profile of ¹⁴N⁺ or other ion species (e.g., SiV, GeV) for similar Ultrafast Electro-Optic Sensing projects.
Material Selection Optimization: Our team assists researchers in selecting the optimal diamond grade (e.g., Optical Grade SCD vs. High Purity SCD) based on specific experimental parameters, such as required coherence time and operating temperature.

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

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41467-025-63936-8