Analyses of All-Optical Ultra-Fast Gate Switches Using Cascaded Second-Order Nonlinear Effect in Periodically Poled Lithium Niobate Waveguides: Methods of Performance Enhancement and Effects of Device Fabrication Errors

We analyze the switching performance of all-optical ultra-fast gate switches employing the cascade of second harmonic generation and difference frequency mixing in periodically poled lithium niobate waveguides with consideration for crosstalk effect and device fabrication errors. An appropriate time offset between the gate and signal pulses can improve the switching efficiency, and the use of the nonlinear optical tensor element d₃₁ is favorable for efficient ultra-fast operation when compared to the use of the commonly used maximum tensor element d₃₃. On the other hand, while the switching performance is almost independent of the random duty-cycle error, small amount of the random period error causes significant decrease in the switching efficiency.