Measurement of two-photon absorption coefficient of 1030 nm ultrashort laser pulses on natural diamond color centers

At a Glance

Metadata	Details
Publication Date	2022-01-01
Journal	Оптика и спектроскопия
Authors	Gulina Y.S.
Institutions	P.N. Lebedev Physical Institute of the Russian Academy of Sciences
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Analysis: Two-Photon Absorption in Diamond Color Centers

Executive Summary

This research confirms the critical role of material purity and defect density in the nonlinear optical performance of diamond under high-intensity ultrashort laser irradiation. The findings directly support the use of high-purity synthetic diamond for advanced optical applications.

Core Mechanism Confirmed: Two-Photon Absorption ($\beta_{2}$) is the dominant attenuation mechanism in diamond at 1030 nm wavelength and intensities up to 10 TW/cm².
Measured Coefficient: The TPA coefficient ($\beta_{2}$) was determined to be 4.1 $\pm$ 0.3 cm/TW for both 0.3 ps and 10 ps pulses.
Purity Criticality: The nonlinear absorption is explicitly attributed to induced color centers (defects), underscoring the necessity of using materials with minimal intrinsic nitrogen and vacancy concentrations.
6CCVD Solution: 6CCVD specializes in high-purity, optical-grade Single Crystal Diamond (SCD) grown via MPCVD, offering superior defect control compared to the natural diamond used in this study.
Application Relevance: This data is vital for engineers designing high-power laser systems, laser micromachining tools, and quantum optics platforms requiring ultra-low loss dielectric materials.
Custom Optical Components: 6CCVD provides custom, highly polished, plane-parallel SCD plates up to 500 µm thick, ensuring optimal transmission and minimal scattering losses for high-intensity experiments.

Technical Specifications

The following table summarizes the key experimental parameters and the resulting two-photon absorption data extracted from the study.

Parameter	Value	Unit	Context
Material Studied	Natural Diamond	N/A	1 mm thick, plane-parallel plate
Laser Wavelength ($\lambda$)	1030	nm	Fiber Yb⁺³ ion laser source
Pulse Duration ($\tau$)	0.3 and 10	ps	Used for TPA measurement
Pulse Repetition Rate	2	kHz	Experimental setup parameter
Maximum Intensity ($I_{0}$)	10	TW/cm²	Limit where TPA dominates
Two-Photon Absorption Coefficient ($\beta_{2}$)	4.1 $\pm$ 0.3	cm/TW	Key result for 1030 nm pulses
Focusing Objective NA	0.55	N/A	High numerical aperture
Focal Length ($f’$)	5	mm	Short focal length
Focal Spot Radius ($w_{0}$)	1.17	µm	Calculated radius (1/e energy level)
Sample Depth Focused	100	µm	Under the front surface

Key Methodologies

The experiment utilized a Z-scan-like transmission measurement setup to determine the nonlinear absorption coefficient.

Sample Preparation: A 1 mm thick, plane-parallel plate of natural diamond, polished on both sides, was used as the test sample.
Laser Source: A Fiber Yb⁺³ ion laser (Amplitude Systemes Satsuma) provided 1030 nm, linearly polarized ultrashort pulses at a 2 kHz repetition rate. Pulse durations of 0.3 ps and 10 ps were tested.
Focusing System: Laser radiation was focused 100 µm beneath the front surface of the sample using a high-NA microscope objective (NA = 0.55, $f’$ = 5 mm).
Transmission Measurement: An energy meter (Ophir PD10-C) was positioned beneath the sample to record the energy transmitted through the diamond plate.
Data Analysis: Nonlinear transmission ($T_{NL}$) was measured as a function of incident intensity ($I_{0}$). The data was fitted to the theoretical model (Equation 3) to confirm the two-photon nature of the absorption ($n=2$) and calculate the coefficient $\beta_{2}$.

6CCVD Solutions & Capabilities

The research highlights that nonlinear absorption in diamond is primarily driven by color centers (defects). 6CCVD’s expertise in high-purity MPCVD diamond growth provides a direct solution for minimizing these defects, enabling superior performance in high-intensity laser applications.

Applicable Materials for Replication and Extension

To replicate this research with higher fidelity and extend it to higher power regimes, 6CCVD recommends materials engineered for ultra-low defect density:

6CCVD Material	Description & Advantage	Relevance to Study
Optical Grade SCD	High-purity Single Crystal Diamond (SCD) with extremely low nitrogen content (< 1 ppb). Type IIa equivalent.	Minimizes intrinsic color centers (e.g., NV centers), leading to lower linear and nonlinear absorption ($\beta_{2}$) and higher laser damage threshold (LDT).
Standard SCD	General purpose SCD, suitable for thermal management and moderate optical use.	Cost-effective option for initial testing, but Optical Grade is recommended for critical TPA measurements.
Polycrystalline Diamond (PCD)	Available in large areas (up to 125 mm), suitable for large-aperture optics where grain boundaries are acceptable.	Useful for scaling up large-area optical components, though SCD is preferred for minimizing scattering and maximizing purity in TPA studies.

Customization Potential for Advanced Research

The study utilized a specific 1 mm thick, polished, plane-parallel plate. 6CCVD can precisely match or exceed these specifications:

Custom Dimensions and Thickness:
- We provide SCD plates with thicknesses ranging from 0.1 µm up to 500 µm, allowing researchers to optimize sample thickness for specific TPA path lengths.
- Custom laser cutting services ensure precise lateral dimensions required for integration into complex optical setups.
Superior Polishing:
- The study requires highly polished, plane-parallel surfaces to minimize reflection and scattering losses.
- 6CCVD guarantees ultra-smooth polishing: Ra < 1 nm for SCD and Ra < 5 nm for inch-size PCD, significantly reducing surface-induced damage and scattering.
Metalization Services:
- While this study focused on bulk transmission, future integration into high-power systems may require electrical contacts or reflective coatings.
- 6CCVD offers in-house metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu, for creating custom electrodes or reflective surfaces directly on the diamond substrate.

Engineering Support

6CCVD’s in-house PhD engineering team specializes in the material science of MPCVD diamond for high-power optics and quantum applications.

Material Selection Consultation: We assist researchers in selecting the optimal diamond grade (SCD vs. PCD, purity level) and orientation for projects involving high-intensity laser structuring, micromachining, or nonlinear optics.
Defect Engineering: For researchers intentionally studying color centers (e.g., NV centers for quantum applications), 6CCVD offers controlled nitrogen doping and post-growth processing to achieve specific defect densities, extending the scope of this TPA research.
Global Logistics: We ensure reliable global shipping (DDU default, DDP available) of sensitive optical components.

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

View Original Abstract

An experimental study of nonlinear absorption process of ultrashort laser pulses in bulk of natural diamond has been carried out. The results of experimental studies on measuring nonlinear transmission of 1 mm thick plane-parallel plate made of diamond irradiated with focused by micro lens (NA=0.55 with focal length f’=5 mm) 0.3 and 10 ps laser pulses with 1030 nm wavelength are presented. It is shown that in this sample the main attenuation mechanism of ultrashort laser pulses with 1030 nm wavelength at intensities not exceeding 10 TW/cm 2 is two-photon absorption at color centers, the absorption coefficient β 2 =4.1 ± 0.3 cm/TW is determined. Keywords: femtosecond laser pulses, nonlinear absorption, natural diamond, multiphoton absorption, color centers.

Tech Support

Original Source

DOI: https://doi.org/10.21883/eos.2022.04.53730.60-21