The combination of proton-exchange technique and electron-beam lithography for integrated waveguides

We proposed a new method to fabricate waveguides with low loss and reduced dimension. This method combines the conventional proton-exchange technique for long straight segments of waveguide made of Lithium Niobate and the Electron-beam (E-beam) lithography for splitting/bending points. Advantages of both techniques allow low loss of propagation in long distance, and a near-zero loss at sharp splitting/bending angle. They therefore allow reduced size of waveguides to several tens micrometers or smaller. Transmission of light with wavelength lambda₀ of 632.8 nm on proton exchanged waveguides was measured. The extraction ratio between two outputs was measured as 1.03. The simulation of the photonic crystal waveguide for the replacement of light splitting part was also carried out, and demonstrated the functionality for low loss light transmission. The combined method is appropriate for many applications like waveguides, modulators, divider, etc.