Characteristics of all-optical ultrafast gate switches using cascade of second-harmonic generation and difference frequency mixing in quasi-phase-matched lithium niobate waveguides
Characteristics of all-optical ultrafast gate switches using cascade of second-harmonic generation and difference frequency mixing in quasi-phase-matched lithium niobate waveguides
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DOI：
10.1109/jqe.2005.845357
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发表时间：
2005-05-01
影响因子：
2.5
通讯作者：
Maeda, J
中科院分区：
文献类型：
--
作者：
Fukuchi, Y;Akaike, M;Maeda, J
在采用准相位匹配(QPM)铌酸锂(LN)器件二次谐波产生和差频混频级联的全光门开关中，基波脉冲和二次谐波脉冲之间的走离会导致开关的串扰。数值计算了考虑串扰影响的准PM-LN光波导器件的开关性能，并讨论了LN晶体中非线性光学张量元件的有利选择。在分析中，在串扰保持在由切换信号的允许功率损失确定的临界水平以下的条件下，对于给定的比特率，器件长度被最大化。结果表明，门脉冲和信号脉冲之间的时间偏差可以补偿走离，并能显著提高开关效率。在超过1Tbps的超快操作中，发现与使用通常使用的最大张量元件d(33)相比，使用非线性光学张量元件d(31)是有利的。
In all-optical gate switches that employ the cascade of second-harmonic generation and difference frequency mixing in quasi-phase-matched (QPM) lithium niobate (LN) devices, walkoff between the fundamental and second-harmonic pulses causes crosstalk of the switch. We numerically calculate the switching performance of QPM-LN waveguide devices with consideration for the crosstalk effect, and discuss the favorable choice of the nonlinear optical tensor element for the LN crystal. In the analyses, the device length is maximized for a given bit rate under the condition that the crosstalk is maintained below a critical level that is determined by the allowable power penalty for the switched signal. It is shown that the time offset between the gate and signal pulses can compensate for the walkoff, and can significantly improve the switching efficiency. In ultrafast operation beyond 1 Tbps, the use of the nonlinear optical tensor element d(31) is found to be favorable when compared to the use of the commonly used maximum tensor element d(33).