Multi-gigahertz laser generation based on monolithic ridge waveguide and embedded copper nanoparticles
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-01-01 |
| Journal | Chinese Optics Letters |
| Authors | Chi Pang, Rang Li, Ziqi Li, Ningning Dong, Jun Wang |
| Institutions | Wuhan University, Shanghai Institute of Optics and Fine Mechanics |
| Citations | 7 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Multi-Gigahertz Laser Generation using Embedded Copper Nanoparticles
Section titled âTechnical Documentation & Analysis: Multi-Gigahertz Laser Generation using Embedded Copper NanoparticlesâThis document analyzes the research paper âMulti-gigahertz laser generation based on monolithic ridge waveguide and embedded copper nanoparticlesâ to highlight key technical achievements and propose superior material solutions leveraging 6CCVDâs expertise in MPCVD diamond fabrication.
Executive Summary
Section titled âExecutive SummaryâThis research successfully demonstrates a compact, high-frequency mode-locked laser integrated onto a monolithic chip, validating a critical pathway for next-generation integrated photonics.
- Monolithic Integration: A pulsed laser device was realized on a single Nd:YAG chip by combining ion implantation (for saturable absorber synthesis) and diamond saw dicing (for ridge waveguide fabrication).
- High-Speed Performance: The device achieved a fundamental repetition rate of 7.8 GHz and an ultra-short pulse duration of 24.8 ps at 1064 nm.
- Novel Saturable Absorber (SA): Copper (Cu) nanoparticles (NPs), synthesized via direct Cu+ ion implantation, acted as the SA through localized surface plasmon resonance (LSPR) and evanescent field coupling.
- High Nonlinearity: The Cu NPs exhibited pronounced saturable absorption at 1030 nm, with a calculated saturation intensity of 12.9 GW/cm2.
- Low Loss Waveguiding: The fabricated ridge waveguide demonstrated superior optical quality, achieving a low waveguide loss of 0.68 dB at the operating wavelength.
- 6CCVD Relevance: The fabrication techniques (precision dicing, custom dimensions, integration of functional layers) align directly with 6CCVDâs core capabilities, offering a clear path to transition this technology to high-performance diamond substrates.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Repetition Rate | 7.8 | GHz | Mode-locked pulsed laser output |
| Pulse Duration | 24.8 | ps | Single pulse width |
| Maximum Output Power | 58 | mW | Achieved at 836 mW launched power |
| Laser Threshold | 214 | mW | Launched power |
| Operating Wavelength | 1064 | nm | Nd3+ ion 4F3/2 â 4I11/2 transition |
| Saturable Absorption (SA) Wavelength | 1030 | nm | Measured via Z-scan technique |
| Saturation Intensity (Is) | 12.9 | GW/cm2 | Nonlinear optical response of Cu NPs |
| Modulation Depth | 1.5 | % | Saturable absorption characteristic |
| Waveguide Loss (α) | 0.68 | dB | Measured at 1064 nm (TM polarization) |
| Ridge Waveguide Width | 23.5 | ”m | Defined by diamond saw dicing |
| Cu NP Mean Diameter | 2.16 | nm | Synthesized via ion implantation |
| Cu+ Implantation Fluence | 1 x 1017 | ions/cm2 | Used for NP synthesis |
| C4+ Irradiation Fluence | 6 x 1014 | ions/cm2 | Used for planar waveguide formation |
Key Methodologies
Section titled âKey MethodologiesâThe monolithic ridge waveguide chip with embedded Cu NPs was fabricated using a combination of ion beam engineering and precision mechanical processing:
- Substrate Selection: A Nd:YAG crystal (10 mm x 10 mm x 2 mm) was utilized as the base material.
- Nanoparticle Synthesis: Cu+ ions were implanted into the Nd:YAG surface at an energy of 100 keV and a fluence of 1 x 1017 ions/cm2. This process aggregated the impurity atoms to form Cu NPs, primarily distributed between 50 nm and 125 nm depth.
- Planar Waveguide Formation: C4+ ions were subsequently irradiated into the sample at 15 MeV with a fluence of 6 x 1014 ions/cm2, creating a low-index damage layer approximately 10 ”m thick beneath the surface, thus forming a planar optical waveguide.
- Ridge Waveguide Fabrication: A rotating diamond blade (2000 r/min) was employed for high-speed dicing to create parallel air grooves, defining the 23.5 ”m wide ridge waveguide structure.
- Nonlinear Characterization: The ultrafast nonlinear optical response was measured using an open-aperture Z-scan system excited by a 340 fs pulsed laser at 1030 nm to confirm saturable absorption.
- Laser Implementation: An end-face coupling system was used to launch the 808 nm pump laser and implement mode-locking via evanescent field interaction between the waveguide mode and the embedded Cu NPs.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful integration of high-speed laser generation on a monolithic chip, as demonstrated in this paper, requires exceptional material quality, thermal management, and precision fabricationâall core competencies of 6CCVD. By transitioning this technology to MPCVD diamond, researchers can achieve superior performance, especially in high-power or high-temperature environments.
| Research Requirement/Challenge | 6CCVD Solution & Capability | Technical Advantage |
|---|---|---|
| Thermal Management (Critical for high-power GHz operation) | Optical Grade Single Crystal Diamond (SCD) | SCD offers the highest known thermal conductivity (> 2000 W/mK), enabling orders of magnitude better heat dissipation than Nd:YAG, crucial for scaling output power and maintaining stability. |
| Precision Waveguide Fabrication (Required 23.5 ”m ridge definition) | Custom Dicing and Laser Cutting Services | 6CCVD utilizes high-precision diamond dicing and laser cutting to define complex ridge, channel, or rib waveguide structures on SCD and PCD substrates with micron-level accuracy. |
| Large Area Integration (Scaling monolithic chips) | Large-Format PCD Wafers | We supply Polycrystalline Diamond (PCD) plates up to 125 mm in diameter, facilitating the scale-up and mass production of integrated photonic circuits. |
| Ultra-Low Loss Surface Quality (Required Ra < 1 nm for low scattering) | Superior Polishing Specifications | SCD substrates are polished to an industry-leading surface roughness of Ra < 1 nm, minimizing scattering losses critical for evanescent field coupling and low waveguide loss (0.68 dB achieved in the paper). |
| Integration of Functional Layers (Cu NPs used as SA) | Custom Metalization Services | 6CCVD offers in-house deposition of plasmonic and contact metals (Au, Pt, Pd, Ti, W, Cu) directly onto diamond surfaces, allowing for the integration of custom saturable absorbers or electrodes. |
| Applicable Materials | Boron-Doped Diamond (BDD) Films | BDD, available in thicknesses from 0.1 ”m to 500 ”m, can function as a robust, wide-band saturable absorber, providing a diamond-native alternative to external NP layers for mode-locking applications. |
| Thickness Requirements (Waveguide thickness ~10 ”m) | Custom SCD/PCD Thicknesses | We provide SCD and PCD films in precise thicknesses ranging from 0.1 ”m to 500 ”m, allowing engineers to optimize waveguide geometry and evanescent field interaction depth. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD engineering team specializes in the material science and application of MPCVD diamond for high-power optics and integrated photonics. We offer consultation services to assist researchers in selecting the optimal diamond grade (SCD, PCD, or BDD) and defining custom fabrication parameters (dimensions, metalization, polishing) required to replicate or extend this high-performance integrated laser research onto a diamond platform.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Copper (Cu) nanoparticles (NPs) are synthesized under the near-surface region of the Nd:Y3Al5O12 (Nd:YAG) crystal by direct Cu+ ions implantation. Subsequently, the monolithic ridge waveguide with embedded Cu NPs is fabricated by C4+ ions irradiation and diamond saw dicing. The nonlinear optical response of the sample is investigated by the Z-scan technique, and pronounced saturable absorption is observed at the 1030 nm femtosecond laser. Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal, 1 ÎŒm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes, reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz. The work combines waveguides with NPs, achieving pulsed laser devices based on monolithic waveguide chips.