非对称Y分支光波导分路器的设计

在分析了非对称Y分支平面光波导理论的基础上,利用BPM算法,对Ti:LiNbO3分支波导进行了计算和仿真,得到了其分叉角与功率分配的关系;同时对几个Y分支级联所构成的非对称分路器进行了研究,结果表明利用非对称光分路器分配光功率,可以满足不同用户的需求.这为制作光分支器提供了一种新的设计思路.     

一种带有锥形多模过渡区的Y分支光波导

为减小Y分支波导的分支损耗,提出在输入波导和两输出波导间引入锥形多模过渡波导.与已被用于减小Y分支波导分支损耗的矩形多模过渡波导相比,所引入的锥形多模过渡波导,不仅可以减小过渡波导的长度,还可进一步减小分支损耗.利用三维有限差分光束传播法,对具有锥形过渡波导的退火质子交换铌酸锂Y分支光波导进行了数值模拟.数值结果为该类Y分支光波导的设计和制备提供参考.     

两种不同Y分支光波导的弯曲损耗研究

针对低损耗S型弯曲Y分支的分析与设计,分别用弯曲损耗理论和有限差分光束传输法分析了两种不同的S型弯曲Y分支的损耗特性,比较了不同的波导宽度、分支间距和分支张角对波导输出损耗特性的影响,得出了一组最优化的Y分支波导设计参数.     

余弦型Y分支结构参数的性能分析

针对低损耗余弦型Y分支光波导的分析与设计,首先对其弯曲损耗进行理论推导,其次对光传播损耗特性起主要影响作用的三个结构参数(波导宽度、过渡区长度、分支高度),利用有限差分光束传播法(FD-BPM)进行了逐个性能优化分析.结果表明:传输损耗随波导宽度的增加而减小,随过渡区长度的增长而减小,随分支高度的增加而增大,此结果可为各种Y分支的选取提供参考.     

Y分支波导耦合器中弯曲损耗的研究

本论文围绕着一种用于光纤陀螺光收发模块的Y分支波导耦合器进行设计和模拟。主要对Y分支的弯曲损耗做了理论分析,在相同波导长度和分支高度下,对比余弦弯曲和正弦弯曲;TE、TM场;不同边界条件等参数和结构。通过对各项参数和结构的比较,用基于BPM(Beam propagation method)法的BPM-CAD软件对波导耦合器进行仿真模拟,得到各种结构和参数下不同Y分支波导的归一化功率和波导长度的关系,从而确定其功率损耗,最终设计出一种有效减少功率损耗的Y分之波导结构。     

Y分支3维光波导横截面折射率分布

为了实现一个表达式同时反映Y分支光波导在纵横两方向上的折射率分布,通过对玻璃结构和离子交换过程进行分析,采用逆向分离变量法提出了基于横向和纵向两个方向折射率分布函数乘积的横截面折射率分布函数,并利用MATLAB软件对优化结果进行了编程模拟。利用Tl+-Na+离子交换法在BK7玻璃基底上制备了Y分支12型3维光波导,利用雅明干涉法对光波导横截面的折射率分布进行了测量。结果表明,利用改折射率分布函数模拟得到的Y分支光波导横截面折射率分布与雅明干涉法实验测得的结果吻合。该改进型折射率分布函数可以对Y分支光波导横截面折射率分布进行模拟,能准确快捷地对Tl+-Na+离子交换Y分支3维光波导横截面折射率分布进行重建。     

Y分支结构输出特性的优化

文章分析了平面光波导Y分支的输出特性，通过优化Y分支中扩模波导的长度和插入一根适当长度直波导对Y分支的输出均匀性进行了优化，通过这种优化设计可以获得具有均匀输出特性的Y分支。     

双M-Z干涉仪中Y分支波导设计与分析

介绍了分支波导和S形弯曲波导,设计了对称双Y分支S形弯曲波导的结构,并计算了其弯曲损耗。对1/2Y和1/4Y分支波导的传输及弯曲损耗随长度的变化进行了模拟仿真,结果表明,设计的双Y分支波导达到了低损耗的要求。最后对双M-Z干涉仪的光场传输进行了二维各向同性仿真,得到其光场传输图和折射率分布图。结果表明,设计的双M-Z干涉仪的分光比可达1∶1∶1∶1。     

非对称X结波导混合耦合器的改进型设计

为了减小非对称X结波导混合耦合器的串音和功耗,增大实现模式分离的非对称端分支角,提出了一种改进型设计.用光束传播法结合有效折射率法模拟分析了改进后的非对称X结波导混合耦合器的串音与功耗,结果表明其串音比原来有了大幅度的减小,而且功耗也得到了改善.     

高功率1060 nm半导体激光器波导结构优化

针对高功率1060 nm半导体激光器的外延结构,分析了影响器件功率进一步提高的原因.根据分析,优化了激光器的量子阱结构和波导结构,并理论模拟了波导宽度对模式和输出功率的影响.根据不同模式的光场分布,对量子阱有源区的位置进行了优化,并设计了非对称、宽波导结构.对不同模式的限制因子进行了计算,结果表明,优化后的非对称波导结构能够在降低基模的限制因子的同时,增加高阶模式的损耗.     

Polarization rotation in periodic loaded rib waveguides

Polarization rotation in an asymmetric periodic loaded rib waveguide is analyzed by a scalar coupled-mode theory with vector correction. The scalar modes of the dielectric loaded rib waveguide are calculated by using a simple variational method. The polarization rotation is found to be caused by a geometric effect due to the asymmetric loading of the waveguide. By phase-matching the two polarized modes through the periodic loading, complete polarization rotation can be achieved     

Self-switching in hollow waveguides with a Kerrlike nonlinearpermittivity

The dispersion relations, stability, and excitation of the stationary nonlinear transverse electric (TE) waves guided by a nonlinear hollow waveguide are examined numerically. This waveguide consists of a self-focusing nonlinear film bounded by two identical linear claddings of the higher refractive index. Since a minimum power for guidance of the stationary waves always exists, the nonlinear hollow waveguide acts as a lower threshold device. A stability analysis using the beam propagation method shows that all the stationary TE_n modes, including the asymmetric TE₀ mode, are stable on the positively sloped branch (dP/dβ>0) of the nonlinear dispersion curve. The lower threshold device using the nonlinear hollow waveguide exhibits very sharp power-switching characteristics, and the required device length is fairly short     

非对称单脊波导的积分方程法分析

基于积分方程法的分析途径，本文提出计算任意截面柱形金属波导中主模和高次模的特征值和特征向量的数值方法。本文运用此方法对非对称单脊波导进行了深入的理论和实验研究，给出了该种波导的本征值、电中心线偏移量、壁电流分布、带宽特性、损耗和功率容量等的理论计算结果，这些结果对非对称单脊彼导共线裂缝阵天线单元设计有较高的实用价值。     

Low-loss design method for a planar dielectric-waveguide branch:effect of a taper of serpentine shape

A design method is proposed for a planar dielectric waveguide Y branch with low loss caused by radiation. In contrast to the usual design methods, in which the generation of the radiation wave is kept as small as possible, the present method positively uses, for the first time, the behavior of such a radiation wave. The radiation wave at any local position along a taper section of the Y branch is intentionally generated, and its power conversion and reconversion with the surface-wave mode are controlled to reduce the insertion loss for the surface-wave mode. A design example shows that the low-loss Y branch should have a serpentine-shaped taper, which is an unexpected shape compared to the usual design. The effectiveness of the design method presented is confirmed by comparing the numerical results with those of the usual types of Y branches and with measurements     

LiNbO3 1×2非对称电极Y分叉数字光开关的研究

文章提出一种关于非对称电极低串扰数字光开关的新型设计方案，在Y分叉后端引入S弯曲波导，通过在Y分叉处的非对称电极和弯曲波导的弯曲电极处施加一定的同步电压，实现了比没有S弯曲的开关更低的串扰。此种设计采用有限差分光束传播方法（FDBPM）来分析，模拟结果显示，在光波长为1．55μm时，开关电压8V．串扰〈-25dB。     

Guided modes of a parabolic-core slab waveguide

A formulation for analysing guided modes of a parabolic-core slab waveguide with asymmetric cladding is developed. This method gives the exact solution. The propagation characteristics of the fundamental mode of the TE wave are evaluated.     

Analysis of distributed feedback semiconductor lasers bytwo-dimensional theory

The two-dimensional theory of distributed feedback (DFB) lasers to take account of the planar waveguide structure which was presented in a previous paper (see ibid., vol.26, no.3, p.467-72, 1990) is applied to the analysis of the DFB laser threshold conditions with respect to the effects of the waveguide structure and the facet reflection. The asymmetric properties of the transverse functions of the coupled modes with respect to the Bragg frequency in the dispersion relations are found to be enhanced by the asymmetric index waveguide structure and by the asymmetric facet reflectivity. Therefore, the resulting confinement factor differences in the grating layer between the two adjacent lasing modes on both sides of the Bragg frequency give large threshold gain differences     

TE modes of graded-index slab waveguides

An analysis of the TE modes of a slab waveguide with graded refractive-index distribution is presented. The refractive index is approximated by a piecewise-linear distribution for which exact solutions of the guided-wave problem can be obtained. For multimode guides, useful approximate solutions can be worked out with the help of the Wentzel-Kramers-Brillouin (WKB) approximation. A formula is given for the total number of guided TE modes supported by the waveguide. The coupling efficiency of a prism coupler is investigated by studying the radiation losses of the guided modes escaping from the waveguide through the coupling prism. It is found that the radiation losses of the modes of the graded-index waveguide are more nearly constant than those of the asymmetric slab waveguide.