Second Harmonic Enhanced with Photonic Weyl “Fermi Arcs” on LNOI Chips

Our new paper titled “Probing rotated Weyl physics on nonlinear lithium niobate-on-insulator chips” is published in Physical Review Letters.

In this work, we report the first topological device on a lithium niobate-on-insulator (LNOI) chip. We design a 1D quaternary waveguide lattice on a LNOI chip. Based on this system, we obtain Weyl points and the Fermi arc edge states induced by them with the aid of a synthetic parameter space. We also explore the intriguing rotated Weyl physics in a 3D synthetic space. We find whether the interface between two Weyl structures can host gapless topological interface states or not, is determined by the relative rotational angle of the two Weyl structures. If the two Weyl structures rotate in the same (opposite) direction, topological interface states presence (absence). We also observed experimentally the second-order nonlinear enhancement of the topological interface state due to the second-order nonlinearity of the lithium niobate material.

Our work shows that LNOI provides a flexible platform for many other topological devices. It also opens up a new paradigm for experimentally exploring various applications in integrated nonlinear and quantum optics.

Fig. 1.(a) Cross section diagram of a unit cell that consists four waveguides which simulates the Weyl physics in (b). (c)Domain wall between two Weyl systems formed with waveguides on LNOI chips.

For full text:

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.013901

July 2021