%0 Journal Article
%T Efficient supercontinuum generation in quadratic nonlinear waveguides without quasi-phase matching
%A Hairun Guo
%A Binbin Zhou
%A Michael Steinert
%A Frank Setzpfandt
%A Thomas Pertsch
%A Hung-ping Chung
%A Yen-Hung Chen
%A Morten Bache
%J Physics
%D 2014
%I arXiv
%R 10.1364/OL.40.000629
%X Efficient supercontinuum generation (SCG) requires excitation of solitons at the pump laser wavelength. Quadratic nonlinear waveguides may support an effective self-defocusing nonlinearity so solitons can directly be generated at common ultrafast laser wavelengths without any waveguide dispersion engineering. We here experimentally demonstrate efficient SCG in a standard lithium niobate (LN) waveguide without using quasi-phase matching (QPM). By using femtosecond pumps with wavelengths in the $1.25-1.5 \mu\rm m$ range, where LN has normal dispersion and thus supports self-defocusing solitons, octave-spanning SCG is observed. An optimized mid-IR waveguide design is expected to support even broader spectra. The QPM-free design reduces production complexity, allows longer waveguides, limits undesired spectral resonances and effectively allows using nonlinear crystals where QPM is inefficient or impossible. This result is important for mid-IR SCG, where QPM-free self-defocusing waveguides in common mid-IR nonlinear crystals can support solitons directly at mid-IR ultrafast laser wavelengths, where these waveguides have normal dispersion.
%U http://arxiv.org/abs/1412.3226v1