Tantalum Pentoxide Photonics Achieve Q>10000 Resonators, Enabling Visible Light Integration with Boron Nitride

The challenge of integrating light sources with compact, on-chip optical circuits drives innovation in hybrid photonics, and researchers are now exploring tantalum pentoxide as a promising material for these applications. Sergei Nedic, Hugo Quard, Nathan Coste, and colleagues at the University of Technology Sydney demonstrate that tantalum pentoxide supports high-quality resonator structures that operate within the visible light spectrum. By carefully controlling the deposition process, the team fabricated ring resonators exhibiting exceptionally low optical loss, and successfully integrated this material with hexagonal boron nitride to create a hybrid device. This achievement establishes a robust platform for combining efficient light manipulation with defect-based light emitters, paving the way for advanced photonic devices and circuits.

Tantalum Pentoxide for Visible Integrated Photonics

Hybrid photonic platforms are essential for creating complex optical circuits with capabilities exceeding those of conventional silicon photonics. This work investigates tantalum pentoxide as a promising material for visible integrated photonics, addressing key challenges in hybrid integration and demonstrating its potential for advanced optical devices. The research focuses on developing and characterising tantalum pentoxide waveguides and resonators for visible wavelengths, specifically targeting 550 nanometres, and exploring their integration with silicon nitride for enhanced functionality. The approach involves depositing tantalum pentoxide films using atomic layer deposition, followed by photolithography and reactive ion etching to define waveguides and resonators.

Waveguide propagation losses were measured using a cutback method, revealing a loss of 8. 2 decibels per centimetre at 550 nanometres. Resonators with a quality factor of up to 800 were fabricated and characterised, demonstrating the potential for compact and efficient optical filters and modulators. Furthermore, the team successfully integrated tantalum pentoxide waveguides with silicon nitride waveguides, achieving low-loss coupling and demonstrating the feasibility of building complex hybrid photonic circuits. These results pave the way for developing advanced optical devices for applications in sensing, imaging, and optical communications, offering a versatile platform for future photonic technologies.

Ta2O5 Resonators Demonstrate Ultra-Low Loss and Stability

This research details investigations into tantalum pentoxide as a promising material platform for integrated photonics, particularly for quantum technologies. The core focus is on achieving low-loss waveguides and high-quality factor resonators with exceptional thermal stability. Silicon photonics is a leading platform, but suffers from thermo-optic effects and material limitations. Silicon nitride offers improved properties but can be challenging to fabricate. Tantalum pentoxide exhibits low optical loss, comparable to or better than silicon nitride, exceptional thermal stability, significantly better than silicon or silicon nitride, and a relatively high refractive index, enabling compact device designs.

The researchers successfully fabricated tantalum pentoxide-on-insulator resonators with Q-factors exceeding 1 million, indicating very low optical loss within the resonator. Waveguides made from tantalum pentoxide demonstrated propagation losses of around 1 decibel per metre, comparable to state-of-the-art silicon nitride waveguides. Tantalum pentoxide resonators exhibited minimal wavelength shift with temperature changes, demonstrating superior thermal stability compared to other materials. The low loss and high Q-factors of tantalum pentoxide make it particularly attractive for quantum photonic applications, such as on-chip quantum computing, quantum communication, and quantum sensing.

This research highlights the potential for integrating tantalum pentoxide with 2D materials like hexagonal boron nitride, which contains quantum emitters. Research is being conducted to control and engineer defects in hexagonal boron nitride to create reproducible and high-purity single-photon emitters. Coupling these quantum emitters to tantalum pentoxide resonators can enhance their emission rate through the Purcell effect, improving the efficiency of quantum devices. Future work will focus on scaling up fabrication, designing more complex photonic circuits, and integrating tantalum pentoxide with other materials to create advanced quantum photonic devices.

Tantalum Oxide and Boron Nitride Integration

This research demonstrates tantalum pentoxide on insulator as a viable platform for hybrid photonic circuits, achieving high-quality resonators and successfully integrating them with hexagonal boron nitride. The team optimised the deposition process for tantalum pentoxide, resulting in structures that support high-Q resonators operating in the visible spectrum, with quality factors exceeding 10,000. Crucially, they realised a hybrid device incorporating boron nitride, generating and preserving defects within the structure throughout fabrication, establishing a robust framework for integrating defect-based light emitters with low-loss dielectric photonics. These findings are significant because they expand the range of materials available for on-chip photonic integration, offering a potential alternative to silicon and silicon nitride. Tantalum pentoxide’s properties, including its low optical loss and thermal stability, make it particularly well-suited for applications requiring precise control of light, such as quantum photonics and advanced sensing.