In order to enhance the conversion performance of all-optical logic gates, conversion efficiency of all-optical logic AND gate is explored. The three-level transition rate equations of quantum dot semiconductor optical amplifier (QD-SOA) and the light field transfer equations are solved by Newton method and the forth-order Runge-Kutta method. The conversion efficiency and the bit error rate of all-optical logic AND gate are discussed. The experiment results indicate that the conversion efficiency of all-optical logic AND gate can be raised by increasing the pulse width, maximum modal gain and by decreasing the loss coefficient, the transition time of electrons from excited state (ES) to the ground state (GS).As the length of the active region increases, the conversion efficiency increases first and then decreases. When pulse width is 2.0 ps, loss coefficient is 160/m, the length of the active region is 2.0 mm, the transition time of electrons from ES to GS is 0.16 ps and maximum modal gain is 3000/m, the conversion efficiency is improved to 7.1475 dB. However, it is necessary to choose appropriate length of the active region, pulse width and the transition time of the electron from ES to GS, because there is a certain discrepancy between the higher conversion efficiency and the lower bit error rate. Therefore, the conversion efficiency and bit error rate should be considered when choosing parameters, so as to improve the conversion efficiency of all-optical logic AND gate and reduce the bit error rate.%为了提高全光逻辑门的转换性能,对全光逻辑与门的转换效率进行研究.采用牛顿法和四阶龙格库塔法求解量子点半导体光放大器(QD-SOA)的三能级跃迁速率方程和光场传输方程,讨论全光逻辑与门的转换效率和误码率.结果显示:增加脉冲宽度、最大模式增益以及减小损耗系数、电子从激发态(ES)到基态(GS)的跃迁时间,都会提高全光逻辑与门的转换效率,而增大有源区长度使得转换效率先增大后减小.分别取脉冲宽度为2.0 ps,损耗系数为160/m,有源区长度为2.0 mm,电子从ES到GS的跃迁时间为0.16 ps,最大模式增益为3000/m时,转换效率提高至7.1475 dB.但是,选取有源区长度、脉冲宽度和电子从ES到GS的跃迁时间须适当,因为同时获得较高的转换效率与较低的误码率之间存在一定的矛盾.因此,选取参数时要兼顾转换效率和误码率,以提高全光逻辑与门的转换效率,同时减小误码率.
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