Higher order mode supercontinuum generation in tantalum pentoxide (TaO) channel waveguide.

We fabricated tantalum pentoxide (TaO) channel waveguides and used them to experimentally demonstrate higher-order mode supercontinuum (SC) generation. The TaO waveguide has a high nonlinear refractive index which was in an order magnitude of 10 cm/W and was designed to be anomalously dispersive at the pumping wavelength. To the best of our knowledge, this is the first time a higher-order mode femtosecond pump based broadband SC has been measured from a nonlinear waveguide using the phase-matching method. This enabled us to demonstrate a SC spectrum spanning from 842 to 1462 nm (at - 30 dB), which corresponds to 0.83 octaves, when using the TM waveguide mode. When using the TE mode, the SC bandwidth is slightly reduced for the same excitation peak power. In addition, we theoretically estimated and discussed the possibility of using the broadband higher-order modes emitted from the TaO waveguide for trapping nanoparticles. Hence, we believe that demonstrated TaO waveguide are a promising broadband light source for optical applications such as frequency metrology, Raman spectroscopy, molecular spectroscopy and optical coherence tomography.