【作者】 张浩；

【导师】 许孝芳；

【作者基本信息】 江苏大学 ， 光学工程（专业学位）， 2022， 硕士

【摘要】 随着信息技术的飞速发展,人类对信息传输和处理的速度有着更高的要求,当前以电子作为信息载体的电子器件发展遇到了瓶颈。而与电子器件相比,以光子作为信息载体的光子器件具有传递信息量大、功耗低、带宽大、响应时间短等优点,使用光子器件代替电子器件已成为推动信息技术发展的一种方法。由于光子晶体具有优秀的控制光子的能力,使用光子晶体设计的光子器件具有设计灵活、易于集成、结构紧凑、响应时间短等优点,因此使用光子晶体设计光子器件成为了研究的热点。本文基于向列相液晶设计了一种传输效率可调控的光子晶体波导和一种输出可调控的1×4光子晶体分束器,同时基于BPSK信号设计了一种光子晶体逻辑门和一种光学半加器。文中采用平面波展开法和有限元分析法对所设计的几种光子晶体器件进行了模拟分析。具体的研究内容如下:（1）通过在“Z”型光子晶体波导两个水平通道之间的倾斜通道中放置液晶组件,设计了一种传输效率可调控的光子晶体波导。对液晶组件施加电压可以改变其内部向列相液晶的折射率。当不对波导中任何一个液晶组件施加电压时,波导的传输效率非常高;当对波导中所有的液晶组件施加电压时,波导的传输效率非常低。对不同数量和不同位置的液晶组件施加电压,可以有效调控光子晶体波导的传输效率。通过在1×4光子晶体分束器的分束端口放置液晶组件,设计了一种输出可调控的1×4光子晶体分束器。对不同分束通道中所有液晶组件施加电压,可以控制光从指定的输出端口输出;对不同分束通道中单个液晶组件施加电压,可以在保证较高传输效率的情况下调控各个输出端口的分光比。（2）在基于BPSK信号设计的光子晶体逻辑门和光学半加器中,输入端口的逻辑状态由入射光的初始相位决定,输出端口的逻辑状态由输出光的光强决定。通过在光子晶体结构中构建两个波导和一个包含Si O₂介质柱的微腔,设计了一种光子晶体逻辑门。不同初始相位的两束入射光经过微腔耦合后,会在逻辑门中产生干涉,使输出端口输出光的光强大小改变,逻辑门两个输出端口分别可以实现XOR和XNOR逻辑。通过对所设计的逻辑门引入初始相位固定的参考光束,设计了一种光学半加器。参考光束会与经过微腔耦合的入射光在光学半加器中产生干涉,使输出端口输出光的光强大小改变。我们所设计的逻辑门和光学半加器具有结构简单、占地面积小、响应时间短,输出信号边缘差大等优点。更多还原

【Abstract】 With the rapid development of information technology,human beings have higher requirements for the speed of information transmission and processing.At present,the development of electronic devices with electronics as information carrier has encountered a bottleneck.Compared with electronic devices,photonic devices with photons as information carriers have the advantages of large amount of information transmission,low power consumption,large bandwidth and short response time.Using photonic devices instead of electronic devices has become a method to promote the development of information technology.Because photonic crystals have excellent ability to control photons,photonic devices designed with photonic crystals have the advantages of flexible design,easy integration,compact structure and short response time.Therefore,the use of photonic crystals to design photonic devices has become a research hotspot.In this paper,a photonic crystal waveguide with tunable transmission efficiency and a 1×4photonic crystal beam splitter with adjustable output are designed based on nematic liquid crystal.At the same time,a photonic crystal logic gate and an optical half adder are designed based on BPSK signal.In this paper,several photonic crystal devices designed are simulated and analyzed by plane wave expansion method and finite element analysis method.The specific research contents are as follows:（1）A photonic crystal waveguide with adjustable transmission efficiency is designed by placing liquid crystal components in the inclined channel between two horizontal channels of"Z"photonic crystal waveguide.Applying a voltage to the liquid crystal component can change the refractive index of the internal nematic liquid crystal.When no voltage is applied to any liquid crystal component in the waveguide,the transmission efficiency of the waveguide is very high;when voltage is applied to all liquid crystal components in the waveguide,the transmission efficiency of the waveguide is very low.The transmission efficiency of photonic crystal waveguides can be effectively controlled by applying voltage to different numbers and positions of liquid crystal components.A 1×4 photonic crystal beam splitter with adjustable output is designed by placing liquid crystal components at the beam splitting port of the 1×4 photonic crystal beam splitter.Applying voltage to all liquid crystal components in different beam splitting channels can control the output of light from the specified output port;applying voltage to a single liquid crystal component in different beam splitting channels can control the light splitting of each output port while ensuring high transmission efficiency.（2）In the photonic crystal logic gates and optical half adders designed based on BPSK signals,the logic state of the input port is determined by the initial phase of the incident light,and the logic state of the output port is determined by the light intensity of the output light.A photonic crystal logic gate is designed by constructing two waveguides and a microcavity containing Si O₂dielectric column in the photonic crystal structure.After two beams of incident light with different initial phases are coupled through microcavity,they will interfere in the logic gate and change the light intensity of the output light at the output port.The two output ports of the logic gate can realize XOR and XNOR logic respectively.An optical half adder is designed by introducing a reference beam with fixed initial phase into the designed logic gate.The reference beam will interfere with the incident light coupled through the microcavity in the optical half adder,so that the light intensity of the output light at the output port will be slightly changed.The logic gates and optical half adders we designed have the advantages of simple structure,small footprint,short response time,and large edge difference of output signals.更多还原