Wavelength shifted third harmonic generation in an exposed-core microstructured optical fiber

We demonstrate the ability to control the wavelength of third harmonic generated visible light within an exposed-core microstructured optical fiber. This is achieved by coating dielectric nanofilms onto the exposed-core, which shifts the intermodal phase matching position. A shift of up to 30 nm was achieved using a 50 nm thick tantalum oxide coating. This work paves the way for tuning the position of the phase matching position for the reverse process of triple photon generation for quantum optics applications.