Waveguide design for minimum nonlinear effectivearea and switchingenergy in AlGaAs at half the bandgap

Optical frequency conversion in integrated devices [Invited]

“…AlGaAs has been termed "the silicon of nonlinear optics" [26] due to its excellent nonlinear performance [26,[35][36][37][38]. In addition to the highest Kerr nonlinearity among the candidates for all-optical signal processing (n 2~1 0 -17 m 2 /W at λ=1.55 μm [36]), it also has a high refractive index allowing for a tight mode confinement for even more efficient nonlinear interactions.…”

All-optical switching in lithium niobate directional couplers with cascaded nonlinearity

“…In the temperature range where large phase shifts occur with small depletion, i.e., T , T PM , the switching curves are nearly identical to the switching curves obtained from x ͑3͒ -based nonlinear directional couplers (NLDC's). 4 Figure 2(a) shows a switching curve at a crystal temperature of 343.5 ± C, where fundamental depletion is still small. We observed an increase in the power required for switching when operating at temperatures even further below T PM , i.e., at larger average wave-vector mismatches and hence decreased cascading nonlinearity.…”

“…However, the current devices switch at peak powers orders of magnitude larger than those of the best x ͑3͒ -based NLDC's. 4 The goal here was to demonstrate that cascading could be used to implement highcontrast switching in a complicated device such as a NLDC with minimal loss to SHG. In the current implementation, the waveguides with their large effective core areas were not optimized to minimize the switching powers, and the geometry used in LiNbO 3 has a relatively small value of x ͑2͒ .…”

“…This should dramatically reduce the power levels required for a given application. Although both all-optical switching and solitonlike propagation based on the nonlinear refractive index have been successfully demonstrated during the past decade, 4,5 the first experiments to conf irm the predictions that typical all-optical x ͑3͒ phenomena can be mimicked with the cascaded second-order nonlinearity were performed only a few years ago. Specifically, in LiNbO 3 channel and slab waveguides the nonlinear phase shifts have been measured, 6 one-dimensional spatial solitons have been observed in planar waveguides, 7 and the nonlinear phase shift was used for what was to our knowledge the f irst demonstration of all-optical switching in a hybrid Mach-Zehnder interferometer.…”

El acoplador direccional en cristales fotónicos planares

“…Esta idea ha sido implementada en distintos tipos de tecnologías entre las que cabe destacar la de AlGaAs donde existen resultados experimentales [Vil92]. Esta tecnología presenta un material con un coeficiente Kerr bastante elevado y que minimiza los efectos nocivos que limitan la nolinealidad [Vil95,Del90]. Más recientemente se ha trasladado esta configuración al campo de los cristales fotónicos [Loc04] donde se espera obtener una mejor eficiencia fruto del alto confinamiento de la señal.…”