共查询到18条相似文献,搜索用时 78 毫秒
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设计了一种缺陷模迁移光子晶体微腔全光开关. 两条二维三角晶格空气孔光子晶体波导由一个光子晶体微腔连接, 在微腔的点缺陷中填充掺有少量偶氮聚合物的苯乙炔类液晶. 通过调节控制光的偏振态, 使偶氮聚合物发生顺-反异构化反应, 带动液晶分子重新取向, 从而改变光子晶体微腔的谐振波长, 进而实现光的通过与截止. 运用时域有限差分法和平面波展开法分析 了二维光控液晶光子晶体微腔全光开关的光学特性. 数值计算结果表明: 对于1.55 μ通信波段通过外界偏振光控制所填充的向列相液晶 的折射率可以实现对光波的导通与截止. 分析结果显示, 此开关具有阈值低, 消光比较大, 体积小等优点.
关键词:
二维光子晶体微腔
波导
时域有限差分(FDTD)
液晶 相似文献
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液晶调制光子晶体微腔光衰减器 总被引:4,自引:1,他引:3
设计了一种二维液晶调制光子晶体微腔光衰减器。两条二维三角晶格空气孔光子晶体波导由一个光子晶体微腔连接,在微腔的点缺陷中填充苯乙炔类液晶。通过施加不同电压,电场诱导液晶取向以改变液晶的折射率,从而改变光子晶体微腔的谐振波长,进而实现光传播强度调节。运用时域有限差分方法和平面波展开法分析了二维液晶调制光子晶体微腔光衰减器的光学特性。数值计算结果表明:对于1.55μm通信波段,通过外界电场控制所填充的向列相液晶的方向可以对这种二维液晶调制光子晶体微腔光衰减器实现3.40%~99.58%的可调谐光输出。 相似文献
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为了提高光子晶体波导与传统介质波导的耦合效率,设计了级联缓变结构.先将传统介质波导中的光耦合进尺寸相当的光子晶体W5波导中,然后W5波导中的光被耦合进尺寸较小些的W3波导中,最后光被耦合进尺寸最小的W1波导.各级波导之间由半径逐渐增大的空气孔连接,空气孔半径逐渐变化相当于波导有效折射率在变化,所以各级波导可以看作是被折射率缓变结构连接起来.由于折射率的缓变,使得光从前一级波导耦合进相邻的后一级波导时反射很小,从而能有效地提高耦合效率.数值计算表明,在光子晶体禁带范围内,除了波导有限长度和波导微小禁带造成的微小不通带外,耦合系数一般能达80%左右,最高可达到95%. 相似文献
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设计优化了用于截断二维正方格子介质柱光子晶体波导的分布布拉格反射波导的结构.二维时域有限差分数值模拟结果显示,在上述两种波导联接处的反射系数可以在大部分光子晶体波导导波的频谱范围内降到1%以下.将这种分布布拉格反射波导和通常的吸收边界条件相结合可以构成用于光子晶体波导的吸收边界条件,其反射率可以降低到-40dB以下,吸收层的厚度可取为晶格长度的1.3倍.
关键词:
吸收边界条件
光子晶体波导
时域有限差分 相似文献
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提出并优化了用于二维介质柱光子晶体波导与单模平面介质波导对接的基于分布布拉格反射波导的喇叭波导接头,提高了这两种波导之间的传输效率.二维时域有限差分仿真结果表明,在大部分光子晶体波导导模的频谱范围内,传输效率高于98%.传输效率最高可以达到99.85%.
关键词:
光子晶体波导
平面介质波导
时域有限差分 相似文献
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The zero dispersion point of an index-guided photonic crystal fiber with triangular lattice of air holes has been shifted to 0.65 μm by varying the diameter of air hole of different rings. Using FDTD method, we have estimated group velocity dispersion, effective refractive index, the fiber parameter, and the mode field of the fundamental mode. It has been realized that the value of zero dispersion point is mainly decided by the air holes of the first ring. This fiber can be used for biomedical application, spectroscopy, and supercontinuum generation. 相似文献
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Design of Two 8-Channel Optical Demultiplexers Using 2D Photonic Crystal Homogeneous Ring Resonators
ABSTRACTRing resonators have always been referred to as a highly flexible structure for designing optical devices. In this paper, we have designed and evaluated two 8-channel optical demultiplexers using photonic crystal ring resonators. The purpose of this study is to investigate the flexibility of this type of resonator for designing and manufacturing optical devices based on photonic crystals. To the extent that we have investigated the literature, there is no report so far on such a study. For this purpose, two structures with the same structural parameters, but only with a difference in the type of lattice constant (square or triangular) are used. Both structures have a common photonic band gap within a proper range for telecommunication applications used in wavelength-division multiplexing (WDM) systems. Both designed structures have an average crosstalk of ?26 dB. For the demultiplexer structure with a square lattice constant, the quality factor and the transmission coefficient are 3,046 and 93.7% respectively, and its channel spacing is 1.97 nm. For the structure with a triangular lattice constant, the quality factor and the transmission coefficient are 1577.7 and 94.5%, respectively and its channel spacing is equal to 4 nm. To obtain the photonic band gap of the structures, the plane wave expansion (PWE) method is used and the output spectrum of the structures is obtained using the finite-difference time-domain (FDTD) method. The good results obtained in this study is through designing and simulating optical demultiplexer structures only by creating a change in the type of lattice constant used. This undoubtedly justifies the high flexibility of ring resonators, when used in the design of optical devices, as well as their suitability for the use in WDM systems 相似文献
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提出了一种在二维三角晶格光子晶体线缺陷波导中放置椭圆空气孔的耦合腔波导结构。基于平面波展开法,利用MPB对线缺陷波导的能带结构进行了计算并给出能带图。基于时域有限差分法(FDTD),利用MEEP对椭圆空气孔在波导中的排列方式、数量、尺寸进行优化设计,并对频率位于微腔共振频率处的光波在耦合腔波导结构中的品质因子和传输特性进行研究与比较,给出了电场分布图。仿真结果表明,当椭圆空气孔的长轴方向纵向排列时,相应的微腔共振频率在光子禁带内可获得90%以上的透射率,对应的品质因子Q可达104量级;选择合适的参数,获得的Q可高达107量级,对应共振频率的透射率仍在60%以上。 相似文献
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利用非线性折射率系数较大且非线性时间响应较快的CdSxSe1-x玻璃为材料,设计并制备了非线性一维光子晶体波导光双稳器件,该器件的折射率空间分布呈正弦形式。实验测得双稳开关的阈值功率密度为1.60×105W/cm2,开关时间为63ps。采用时域有限差分方法讨论了光子晶体带隙随入射光强变化而移动的情况,随着入射光功率密度的增加,光子晶体的带隙中心向短波方向移动。同时计算了该器件的双稳特性,理论计算得到双稳开关的阈值功率密度为1.40×105W/cm2,开关时间约为50ps。获得了理论与实验基本一致的结果。 相似文献
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Abstract A detailed theoretical analysis is presented to characterize wave propagation at 1,550 nm inside a glass (SiO2) microring resonator implemented using photonic crystal technology. A photonic crystal reflection is used at each microring resonator corner to enhance the bending efficiency. The characteristics of both photonic crystal beam splitter and microring resonator bending losses are analyzed and investigated using both effective refractive index and finite difference time domain methods. Analytical expressions are also derived to describe the field enhancement inside the microring resonator, the transfer function of the microring resonator, and the main parameters characterizing the resonator such as resonator band width and quality factor. The analysis is also extended to characterize a drop filter implemented using photonic crystal-based microring resonator. The results indicate clearly that the effective refractive index method can give accurate results if one starts the calculations with finite difference time domain-estimated beam splitter parameters. Further, bending efficiency as high as 99% can be obtained using a ten-post layer photonic crystal mirror at each microring resonator corner. 相似文献
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