Single Frequency Laser Inside a Crystal

Project Information

GRAIL

Grant agreement ID: 101026739

DOI

10.3030/101026739

Project closed

EC signature date 26 April 2021

Start date 1 September 2022

End date 31 August 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 160 932,48

EU contribution

€ 160 932,48

Coordinated by

UNIVERSIDAD DE LA LAGUNA
Spain

Periodic Reporting for period 1 - GRAIL (Single Frequency Laser Inside a Crystal)

Reporting period: 2022-09-01 to 2024-08-31

Summary of the context and overall objectives of the project

The outstanding development of photonic technologies that has occurred in recent decades has allowed their implementation with great success in a wide variety of areas such as high-speed communications, sensors, high-precision medicine tools, scientific instrumentation, space technologies, etc. Driven by this trend, the Global Photonics Market was valued at USD 722.31 billion in 2021, and it is expected to reach USD 1089.00 billion by 2027[1]. However, to push forward photonic technologies, two fundamental aspects need to be addressed.

On the one hand, to create manufacturing processes for the fabrication at sub-micrometric scales that are cost-efficient and provide reproducible results at industrial level to evolve photonic and nanophotonic technologies in the same way that the integrated circuit evolved electronics in the second half of the 20th century.
On the other hand, the design and functional demonstration of a family of versatile and robust photonic devices able to work under harsh environmental conditions to address the requirements of the most demanding applications.

Funded by the Marie Skłodowska-Curie Actions programme, the GRAIL Project focused on the study, application and improvement of a novel 3D nanolithography fabrication technique for the development of fully monolithic and crystalline photonic elements (e.g. waveguides, diffraction gratings, etc) and devices (e.g. full laser cavity), emphasizing on miniaturization, reproducibility and capabilities to bring the technique to high levels of integration and mass production.

The GRAIL project successfully demonstrated the feasibility of utilizing the 3DLW technique in combination with giant wet-etching selectivity to fabricate photonic components relying on pronounced refractive index steps. Additionally, the project explored the use of 3DLW for controlled small refractive index modulations, uncovering evidence of both positive and negative changes. This breakthrough significantly broadens the possibilities for producing advanced 3D microphotonic devices in both crystalline and non-crystalline materials.

Moreover, the strong collaboration with industrial partners during the project facilitated the demonstration of nanoscale and optical-grade structures produced using current state-of-the-art industrial equipment with minimal adaptations. These achievements not only validate the industrial viability of the techniques but also pave the way for future advancements in photonic device manufacturing.


[1] PHOTONICS MARKET - GROWTH, TRENDS, COVID-19 IMPACT, AND FORECASTS (2022 - 2027), Mordor Intelligence Inc.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The project made advancements in the design and fabrication of photonic crystal waveguides (PCWs), successfully demonstrating experimental PCWs in both undoped and doped YAG materials. By optimizing key fabrication parameters, such as pulse repetition rate, scanning speed, and energy calibration, the project achieved the production of submicron structures with high precision. Valuable insights were gained into the optimization of wet-etching for large-scale PCWs based on steep refractive index changes, providing a pathway for refining future fabrication protocols.

The project also explored the control of permanent small refractive index modulations, unlocking new possibilities for diverse photonic devices and enabling the fabrication of microphotonic components without relying on wet-etching. In collaboration with Wooptix S.L. refractive index changes were systematically characterized versus applied energy dosage using wavefront phase imaging technique (WFPI). Furthermore, the 3DLW technique was validated on state-of-the-art industrial equipment at LightFab GmbH, demonstrating its feasibility for large-scale production of photonic components with minimal adaptations.

The findings were disseminated through open-access publications and presentations at international conferences. The project engaged industrial stakeholders through research visits and collaborative meetings, fostering knowledge transfer and encouraging further collaboration within the EU. Outreach activities targeted diverse audiences, ranging from pre-university students to established researchers.

In summary, the GRAIL project has contributed to the development of the 3DLW technique for creating photonic structures in optical materials, including widely used crystals like YAG, while demonstrating the potential for mass production. The knowledge gained in PCW design provides a robust foundation for future innovations. This work aligns with European policy objectives, promoting technological innovation, industrial competitiveness, and sustainable growth.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The GRAIL project demonstrated that 3DLW can be effectively utilized to fabricate monolithic photonic components in both crystalline and non-crystalline materials, whether doped or undoped. Various experimental waveguide designs were successfully produced by embedding nanopores, nanoplanes, and nanoblocks with slight refractive index changes, either positive or negative. Also, a wet-etching process was employed to remove photomodified material and create voids for specific designs. These waveguides can achieve lengths of several tens of millimeters along the Z-axis, with transverse dimensions in the XY-plane reduced to just a few micrometers. Furthermore, diffractive gratings composed of nanopores, nanoplanes, and nanoblocks with separations ranging from nanometers to millimeters were also fabricated.

The robustness and reliability of the fabrication processes explored in GRAIL pave the way for the mass production of highly integrable and durable devices. These advancements represent a step forward in the development of next-generation photonic devices with promising applications in telecommunications, healthcare, and environmental sensing.

logo-grail.png