Invention:
Innovators at the University of Arizona have overcome the non-uniformity issue of thin-film Lithium Niobate. Adaptive profile poling is promising to realize high nonlinear efficiency with strong material second-order nonlinearity. Nonlinear efficiency can actually increase quadratically with length using this method.
It was shown that the optical momentum mismatch caused by the thickness variation of thin-film Lithium Niobate wafers limits the overall nonlinear efficiency. In contrast to standard periodic poling where the domain inversion period is fixed, a near-ideal sinc function second-harmonic spectrum can be recovered.
Background:
Lithium Niobate is inert and difficult to etch. For decades, waveguides have used ion diffusion or proton exchange which suffer small index contrast and bulky, non-scalable, and expensive devices which require a large driving voltage. Furthermore, uncertainties in the ion implantation depth and chemical-mechanical polishing rate cause thickness variations of the device layer.
This non-uniformity has prevented the repeatable demonstration of high-performance nonlinear devices, as well as the large-scale photonic circuits based on thin-film Lithium Niobate. By implementing adaptive profile poling of nanophotonic Lithium Niobate waveguides, the innovators offer the potential for high overall nonlinear efficiency and future chip-scale integration of classical and quantum photonic systems.
Applications:
- Electro-optic modulation
- High nonlinear efficiency
- Tailored waveguide functionality
- Near-ideal sinc function second-harmonic spectral recovery
- Chip-scale integration of classical and quantum photonic systems
Advantages:
- Possess higher nonlinear coefficients and is more transparent over a wide spectral window than competing AlN, GaAs and GaP materials.
- Outperforms competing periodically poled waveguides which achieved ultrahigh normalized efficiency 20 times higher than state-of the-art diffused waveguides in 2018
