共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhongyan Sheng 《Fiber and Integrated Optics》2003,22(6):373-383
A novel passband flattening method for a planar waveguide demultiplexer based on an etched diffraction grating is presented. A strongly confined taper is formed by etching air trenches at both sides of the input waveguide. The geometric parameters of the taper are optimized by considering the figure of merit, ripple, and loss. Numerical simulation for a design example is given to illustrate the passband flattening method. 相似文献
2.
低插损平坦谱响应阵列波导光栅解复用器优化设计 总被引:4,自引:4,他引:0
通过在输入波导与输入平板波导之间加入一种模式转换结构,获得了一个具有平坦光谱响应,低插损,光谱响应对称的阵列波导光栅型波分复用器,该模式转换结构由一个与输入波导的输出端连接的第一锥形波导,一个与此锥形波导输出端连接的细直波导,一个与细直波导输出端连接的第二个锥形波导以及一个连接输入平板波导和第二个锥形波导的梯形波导组成,通过优化设计梯形波导和第二个锥形波导的形状可以获得较宽的1dB通带带宽和较低的插损,同时光谱响应具有非常好的平坦性,而且通过对第一个锥形波导和细直波导的优化设计,在不引入明显的额外插损的条件下,能大大减小由于输入波导的弯曲引入的光谱响应的不平坦. 相似文献
3.
A flat-topped etched diffraction grating(EDG)demultiplexer with a low polarization-dependent loss(PDL)is designed.A design and simulation method based on the method of moment(MoM)is proposed.A 65-channel EDG demultiplexer with channel spacing of 100 GHz is considered as a design example.A tapered multi-mode interferometer(MMI)is used to flatten the passband of the EDG demultiplexer.The numerical results show that the exit width of the tapered waveguide impacts the loss of the TE case more than that of the TM case.Based on this fact,the exit width of the taper is optimized to obtain the lowest PDL.The tapering angle is also optimized where the minimal ripple is obtained.The designed EDG demultiplexer has an excellent flat-topped spectral response and a very low PDL. 相似文献
4.
提出并设计了一种基于电光聚合物的锥形波导,可用于单模光纤与电光聚合物波导器件之间的连接.锥形波导中采用了宽度锥形和折射率锥形结构.宽度锥形采用劈形形状,通过宽度和折射率的缓慢变化实现模场转换.劈形形状的宽度锥形具有较小的损耗且易于制作,折射率锥形可采用灰度掩膜光刻技术制作.研究了锥形波导的传输损耗与锥形波导的长度、波导宽度和厚度、材料吸收损耗等参数的关系及其优化,分析了锥形波导中的功率传输、模场分布与模式转换效率.结果显示锥形波导的传输损耗小于0.37 dB,光纤-波导-光纤的连接损耗优于1.62 dB,对插入损耗的改善达到8.78 dB,模场转换效率达到了83.7%. 相似文献
5.
利用一维变周期谐振腔阵列和非线性缓变边界,可以实现光波从脊波导到光子晶体平面波导 (PCW)的高效耦合.基于平面波展开法(PWE)和时域有限差分法(FDTD),深入分析和讨 论了普通脊波导、2D-PCW结构和本征模以及工作模式、缓变边界形状等对耦合效率的影响, 从而得出光波从脊波导到2D-PCW、再返回脊波导的统一图景.指出考虑模式转换和采用缓变 边界条件可以极大提高PCW与脊波导间的耦合效率.对PC-PW边界采用线性和非线性缓变结构 进行了仿真,讨论了边界缓变程度对耦合效率的影响.结果表明,采用模式耦合和PC-PW余弦 缓变边界时的耦合效率在较宽的带宽内超过了95%.
关键词:
光子晶体波导
脊波导
PWE
FDTD
耦合边界 相似文献
6.
Analysis and design of the taper in metal-grating periodic slow-wave structures for rectangular Cerenkov masers 下载免费PDF全文
The hybrid-mode dispersion equation of the metal-grating periodic slow-wave structure for a rectangular Cerenkov maser is derived by using the Borgnis function and field-matching methods.An equivalent-circuit model for the taper of the groove depth that matches the smooth waveguide to the metal-grating structure is proposed.By using the equivalentcircuit method,as well as the Ansoft high frequency structure simulator(HFSS) code,an appropriate electromagnetic mode for beam-wave interaction is selected and the equivalent-circuit analysis on the taper is given.The calculated results show that a cumulative reflection coefficient of 0.025 for the beam-wave interaction structure at a working frequency of 78.1 GHz can be reached by designing the exponential taper with a TE z10 rectangular waveguide mode as the input and the desired TE x10 mode as the output.It is worth pointing out that by using the equivalent-circuit method,the complex field-matching problems from the traditional field-theory method for taper design can be avoided,so the taper analysis process is markedly simplified. 相似文献
7.
Shunkang Liu 《International Journal of Infrared and Millimeter Waves》2004,25(3):471-480
Large signal operating equations in TWT have been solved by numerical solve method. The relations between interaction efficiency and design parameters in TWT are analyzed. A fast engineering design method of enhancing efficiency for folded waveguide TWT by velocity resynchronization is described. The computation is shown that the efficiency of Ka-band folded waveguide TWT with double taper can be enhanced over twice as original tube. This method of approach is very useful for tube designer. 相似文献
8.
Seong Soo Park Seog Tae Han Yong Moon Cho Do Heung Je Kwang Dong Kim Dong Chul Park 《International Journal of Infrared and Millimeter Waves》2003,24(6):941-951
In this paper, a design method of an iris-coupled waveguide bandpass filter having 0.1 dB passband ripple and 3.5% ripple bandwidth at the center frequency of 41 GHz is described. Mode matching method is used to analyze H-plane discontinuity of waveguide and an equivalent circuit of the thick inductive obstacle is obtained from the results of the analysis. Simulation and experimental results show the validity of waveguide bandpass filter design method using mode matching method. 相似文献
9.
We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections: an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively. 相似文献
10.
We proposed a simple low-cost acrylic and metal-based Y-branch plastic optical fiber (POF) splitter which utilizes a low cost
optical polymer glue NOA63 as the main waveguiding medium at the waveguide taper region. The device is composed of three sections:
an input POF waveguide, a middle waveguide taper region and output POF waveguides. A desktop high speed CNC engraver is utilized
to produce the mold inserts used for the optical devices. Short POF fibers are inserted into the engraved slots at the input
and output ports. UV curable optical polymer glue NOA63 is injected into the waveguide taper region and cured. The assembling
is completed when the top plate is positioned to enclose the device structure and connecting screws are secured. Both POF
splitters have an average insertion loss of 7.8 dB, coupling ratio of 55: 45 and 57: 43 for the acrylic and metal-based splitters
respectively. The devices have excess loss of 4.82 and 4.73 dB for the acrylic and metal-based splitters respectively. 相似文献
11.
对1.5μm波导型声光TE-TM模式转换光滤波器进行了研究。采用了可降低驱动功率的表面声波导结构。在1.5 ̄1.6μm波段实现了可调滤光,通带宽度小于2nm,达到97¥以上转换率所需的射频驱动功率约80mW(19dBm),器件总插入损耗约9dB。 相似文献
12.
We developed a flat passband acoustooptic filter. For the passband flattening, cascaded bandpass and notch filters with different mode converter lengths and conversion strengths were used. We attained a flat passband with flatness of less than 1 dB in the 2 nm range using the device with a second- to first-stage mode converter length ratio of 1.2. 相似文献
13.
An acrylic-based Y-branch plastic optical fiber (POF) with a middle suspended waveguide taper has been developed. The suspended
high index contrast waveguide taper structure has been designed in such a way that it is surrounded by air-cladding. Non-sequential
ray tracing has been performed on the device giving an insertion loss of 4.68 dB and coupling ratio of 50: 50. The middle
waveguide taper is constructed on the acrylic block itself without using any additional optical waveguiding medium injected
into the engraved taper region. Fabrication of the devices is done by producing the device structures on an acrylic block
using high speed computer numerical control (CNC) machining tool. Input and output POF fibers are inserted into this device
structure in such a way that they are passively aligned to the middle waveguide taper structure. The device shows an insertion
loss of 5.9 dB, excess loss of 2.9 dB and a splitting ratio of 50: 50. 相似文献
14.
《Optics Communications》1987,61(1):11-15
A method for the formation of gradient index tapered optical waveguides with predicted shape is proposed and described analytically. The method is applicable for structures fabricated by electric-field assisted ion-exchange in glass. The technique is based on the control of the taper shape by applying a non-uniform electrical field during the waveguide formation process. For experimental verification optical waveguides with tapers were formed by electrically induced migration of K+ ions. An optical coupler based on such a tapered waveguide has demonstrated 1.2° outcoupled beam divergence. The method proposed can be used to form different integrated optical elements, e.g. mode filters, horn structures etc. 相似文献
15.
《Optik》2014,125(24):7215-7221
Tapered waveguide are used in number of integrated optic devices such as directional couplers, modulators, switches mode converters, etc. Most of the methods analyzing tapered waveguide are numerical in nature. In this paper we present a simple, fast and accurate semi analytical method for z-varying waveguide. However, very few idealized structures can be analyzed directly. The present method consists of separating transverse and longitudinal variation in the wave equation, leading to a differential equation with z-varying coefficients for the field variation along z-axis. For the transverse variation local normal theory is applied. Now this equation is applied to specific taper geometries like linear down taper. Computational are done assuming typical values. We observe variation of power mode profile and mode width. Waveguide loss is also including in the analysis. Finally the analytical simulation results have been verified by the commercial Opti-BPM software. 相似文献
16.
17.
18.
19.
用级联缓变结构实现光子晶体波导和传统波导的耦合 总被引:4,自引:4,他引:0
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
20.
An ultra-low-loss coupler for interfacing a silicon-on-insulator ridge waveguide and a single-mode fiber in both polarizations is presented. The inverted taper coupler, embedded in a polymer waveguide, is optimized for both the transverse-magnetic and transverse-electric modes through tapering the width of the silicon-on-insulator waveguide from 450 nm down to less than 15 nm applying a thermal oxidation process. Two inverted taper couplers are integrated with a 3-mm long silicon-on-insulator ridge waveguide in the fabricated sample. The measured coupling losses of the inverted taper coupler for transverse-magnetic and transverse-electric modes are ∼ 0.36 dB and ∼ 0.66 dB per connection, respectively. 相似文献