In the realm of laser technology, a trio of researchers from the Swiss Federal Institute of Technology in Lausanne (EPFL) have made a significant stride in second-harmonic generation (SHG), a process crucial for converting laser light to higher frequencies. Nikolai Kuznetsov, Zihan Li, and Tobias J. Kippenberg have demonstrated a new approach that could enhance the power and efficiency of laser systems used in various energy and scientific applications.
Second-harmonic generation is a fundamental process in laser technology that enables the conversion of light to higher frequencies. Traditional methods using bulk crystals or ridge waveguides have limitations in efficiency and power output. Recently, integrated photonic circuits using periodically poled lithium niobate (PPLN) have shown promise, but their low optical damage threshold restricts the power output to below one watt.
The researchers have overcome this challenge by using periodically poled thin-film lithium tantalate (PPLT) waveguides. Lithium tantalate offers a higher optical damage threshold than lithium niobate, allowing for higher power outputs. Despite its lower nonlinearity, the team achieved a continuous-wave (CW) output of over one watt with a short waveguide, demonstrating the potential of PPLT circuits for high-power applications.
The team optimized the electrode geometry and poling conditions to achieve reproducible results, despite lithium tantalate’s higher coercive field. Their work, published in the journal Nature Photonics, shows that PPLT waveguides can generate over 0.5 watts of off-chip output at 775 nm under 4.5 watts of pump power. This advancement could lead to more efficient and powerful laser systems for use in integrated lasers, quantum photonics, atomic, molecular, and optical (AMO) physics, optical clocks, and frequency metrology.
For the energy sector, this research could pave the way for more efficient solar power conversion, advanced sensing technologies for oil and gas, and improved laser systems for various industrial applications. The ability to achieve high power outputs with short waveguides could also simplify fabrication processes and reduce costs.
In summary, the researchers have demonstrated a significant improvement in second-harmonic generation using PPLT waveguides, overcoming the limitations of previous methods. Their work opens up new possibilities for high-power laser applications in various fields, including the energy sector.
This article is based on research available at arXiv.