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6CCVD Research

Integrated diamond Raman laser pumped in the near-visible

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2018-01-11
JournalOptics Letters
AuthorsPawel Latawiec, Vivek Venkataraman, Amirhassan Shams-Ansari, Matthew Markham, Marko Lončar
InstitutionsHarvard University, Element Six (United Kingdom)
Citations32
AnalysisFull AI Review Included

Technical Analysis and Documentation for Integrated Diamond Raman Lasers

Section titled “Technical Analysis and Documentation for Integrated Diamond Raman Lasers”

Executive Summary

Section titled “Executive Summary”

This research demonstrates the successful integration of a Continuous-Wave (CW) Raman laser utilizing high-quality Single Crystal Diamond (SCD) microresonators, a critical step toward visible-light integrated photonics.

  • Core Achievement: First demonstration of an integrated CW Raman laser pumped in the near-visible region (750 nm pump).
  • Performance Metrics: Achieved ultra-low lasing threshold of 20 mW input pump power, leading to efficient Stokes output (>1 mW).
  • Material Quality: Utilized electronic-grade SCD to achieve ultra-high quality factors (Q > 300,000 for TE pump modes), representing an order-of-magnitude improvement over previous state-of-the-art results in this wavelength range.
  • Broad Tunability: Demonstrated Stokes emission tunable over a 150 nm (60 THz) bandwidth, corresponding to 17.5% of the center frequency (800 nm - 950 nm range).
  • Integrated Platform: Successfully interfaced the SCD microresonator with directly-written, high-power-handling doped-glass waveguides via an end-fire coupling interface.
  • Future Relevance: This platform directly supports next-generation integrated optics in the visible spectrum, specifically mentioning co-integration with color centers like the Silicon-Vacancy (SiV) for hybrid nonlinear-quantum optics applications.

Technical Specifications

Section titled “Technical Specifications”
ParameterValueUnitContext
Material TypeElectronic-Grade SCDN/A[001]-oriented surface, utilized for high Q.
Q-Factor (TE Pump)301,000N/AMeasured at 750.88 nm pump wavelength.
Q-Factor (TE Stokes)85,000N/AMeasured at 834.34 nm Stokes wavelength.
Q-Factor (TM Pump)75,000N/AReduced Q due to polarization effects.
Q-Factor (TM Stokes)35,000N/ALowest Q-factor measured.
Raman Shift Frequency39.99THzCharacteristic high-frequency optical phonon shift of diamond.
Raman Threshold20mWInput pump power for TE-TE lasing process.
Maximum Stokes Power>1mWObserved at 120 mW input pump power.
External Conversion Efficiency1.7%Measured near the lasing threshold.
Internal Conversion EfficiencyUp to 85%Close to the theoretical maximum (90%).
Effective Raman Gain3.2cm GW-1Calculated value, lower than bulk due to imperfect confinement.
Device Thickness~30”mThinned SCD layer transferred to fused silica.
Waveguide Cross-Section300 x ~300nmWidth and height of finished ring resonators.
Tuning Bandwidth>150 (60)nm (THz)Observed output range (800 nm to 950 nm).

Key Methodologies

Section titled “Key Methodologies”

The fabrication process relied heavily on precise material handling, thinning, and high-resolution lithography on the Single Crystal Diamond (SCD) substrate.

  1. SCD Preparation: Started with a 1x1 mm, ~30 ”m thick, [001]-oriented electronic-grade SCD sample.
  2. Initial Bonding & Thinning: Diamond was loosely adhered to a sapphire carrier, etched (Ar/Cl2 cycled with O2), flipped, cleaned, and etched again to achieve the desired film thickness.
  3. Transfer Bonding: The thinned SCD was debonded using hydrofluoric acid and then re-bonded to a fused silica substrate. The silica surface was activated using O2 plasma (300 mT, 100 W, 1 minute) immediately prior to bonding.
  4. Adhesion Layer Deposition: A ~2 nm thick monolayer of Al2O3 was deposited via Atomic Layer Deposition (ALD) to promote adhesion of the subsequent e-beam resist.
  5. Waveguide Definition: FOx-16 spin-on glass resist was written using multi-pass Electron Beam exposure to define the 60 ”m diameter ring resonators and the 300 nm x 300 nm waveguides.
  6. Impurity Mitigation Annealing (ALD Film): Sample was annealed at 460 °C for 1 hour in O2 to drive impurities out of the ALD film.
  7. Coupling Waveguide Fabrication: Directly-written doped-glass waveguides (using FOx-16 mixed with titanium butanate, Ti(OBu)4) were defined via E-beam lithography to act as spot-size converters for efficient end-fire coupling.
  8. Final Impurity Mitigation Annealing (Waveguides/Surface): Sample was annealed at 460 °C for 3 hours in O2 to remove residual impurities, etch graphitized carbon, and terminate the diamond surface in oxygen bonds.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

6CCVD is an expert provider of high-purity, tailor-made MPCVD diamond, uniquely positioned to supply the materials required to replicate, scale, and advance this cutting-edge integrated Raman laser technology. The superior Q-factors and low thresholds achieved in this research rely fundamentally on the quality of the diamond material and the precision of the substrate preparation—both core strengths of 6CCVD.

Applicable Materials

Section titled “Applicable Materials”

To replicate the high-Q performance necessary for near-visible integrated photonics, researchers require low-loss material platforms.

  • Optical Grade Single Crystal Diamond (SCD): This material is essential for replicating the results. 6CCVD provides Electronic or Optical Grade SCD with extremely low nitrogen content, ensuring minimal absorption in the visible and near-infrared spectrum (750 nm - 950 nm) used for the pump and Stokes wavelengths.
  • Specific Orientation Control: The research utilized a [001]-oriented substrate. 6CCVD offers SCD with specific crystallographic orientations, which is critical for controlling Raman gain dependence and polarization conversion in integrated photonic devices.
  • Custom Thickness SCD Films: The paper required diamond thinned to approximately 30 ”m. 6CCVD offers SCD films grown and supplied in thicknesses ranging from 0.1 ”m up to 500 ”m, allowing engineers to select the optimal thickness for transfer, bonding, and waveguide confinement.

Customization Potential

Section titled “Customization Potential”

The success of this integrated device hinges on tight dimensional control and clean interfacing layers.

Requirement in Paper6CCVD Customization SolutionValue Proposition for the Customer
Small DimensionsCustom Laser Cutting6CCVD provides precision laser cutting and dicing for custom geometries (e.g., 1x1 mm chips, specific facet orientations) from large MPCVD wafers (up to 125mm).
Polishing QualityUltra-Low Roughness PolishingOur in-house polishing achieves Ra < 1 nm for SCD. This surface quality is mandatory for minimizing scattering losses in high-Q microresonators (Q > 300,000) and for reliable substrate bonding.
Integration/MetalizationCustom Metal Stack DepositionAlthough the paper used ALD Al2O3, future hybrid devices often require customized metal contacts (e.g., Ti/Pt/Au, W/Pt). 6CCVD offers internal, precise metalization services to facilitate electrode integration alongside photonic components.

Engineering Support

Section titled “Engineering Support”

This research confirms the critical role of high-quality SCD in advancing integrated quantum and nonlinear optics in the visible spectrum. Specifically, the paper notes the relevance to co-integrating diamond with Silicon-Vacancy (SiV) centers.

6CCVD’s in-house team of PhD material scientists and technical engineers can assist researchers and developers with:

  • Material Selection: Optimizing SCD grade (e.g., low-strain, specific NV/SiV implantation characteristics) for complex projects combining nonlinear Raman effects with quantum emission centers.
  • Substrate Preparation: Consulting on orientation, thickness, and surface termination specifications necessary for successful heterogeneous integration (like the fusion bonding described in the paper).
  • Scale-Up Strategy: Transitioning processes developed on small chips (1x1 mm) to 6CCVD’s large-area PCD or SCD wafers (up to 125 mm).

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly. We deliver globally, with DDU default shipping and DDP available upon request.

View Original Abstract

Using a high-Q diamond microresonator (Q>300,000) interfaced with high-power-handling directly-written doped-glass waveguides, we demonstrate a Raman laser in an integrated platform pumped in the near-visible. Both TM-to-TE and TE-to-TE lasing is observed, with a Raman lasing threshold as low as 20 mW and Stokes power of over 1 mW at 120 mW pump power. Stokes emission is tuned over a 150 nm (60 THz) bandwidth of approximately 875 nm wavelength, corresponding to 17.5% of the center frequency.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2013 - Optical Engineering of Diamond [Crossref]

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