Cerenkov configuration second harmonic generation in proton-exchanged lithium niobate guides

Single Domain Wall Effect on Parametric Processes via Cherenkov-Type Phase Matching

“…When the phase velocity of the fundamental beam v in the waveguide is larger than the phase velocity of second harmonic (SH) v in the substrate, the harmonic radiation emits into the substrate at Cherenkov angle. [2][3][4] We can see that the pattern of CSHG is determined by the geometry of the stimulated nonlinear polarization material. In our experiment of CSHG at domain wall, the well-collimated CSH indicates only the planar domain wall to be the only stimulated nonlinear polarization material, the typical width of which is believed to be less than 100 nm in ferroelectrics.…”

“…It can be seen that CR occurs only when v > v . A similar phenomenon called Cherenkov second harmonic generation (CSHG) is observed in nonlinear optics processes, [2][3][4] when the phase velocity of nonlinear polarization propagates faster than the phase velocity of free light of second harmonics in medium. While these two processes are similar, CSHG has unique features.…”

Overview of Nonlinear Optics

“…The harmonic wave has a phase velocity beyond cutoff www.intechopen.com for the waveguide, so that it propagates freely in the substrate material, acting as the source of the observed Cerenkov radiation. This phase-matching technique creates a beam at a small angle to the waveguide and has been observed in lithium niobate (Li, 1990; as well as nonlinear photonic crystal waveguides (Zhang, 2008). Cerenkov SHG can be important in applications where guided SHG is not desired.…”

Quasi-accord de phase et interactions non linéaires en optique intégrée

“…Cet angle 9 satisfait automatiquement la condition d'accord de phase n d( (ü>) = n(2co) cos8, ce qui permet encore une fois d'avoir une plage d'accord de phase très étendue. Une conception adaptée du guide [38], ou une combinaison avec les techniques de quasi-accord de phase [39], permet de garder 9 petit ce qui maximise le recouvrement et la longueur d'interaction. Les meilleurs résultats obtenus dans cette configuration sont rapportés par K. Yamamoto [40], qui a obtenu 1,6 mW dans le bleu, à partir de lOOmW d'infrarouge couplé dans le guide.…”