Tunable multimode interference coupler

An electrically tunable multimode interference (MMI) coupler/splitter is demonstrated. The device operates by modifying the phase of the multiple self-images that are formed around the midpoint of the MMI structure. This provides a simple way to fine-tune the 50:50 output power split ratio or other arbitrary ratio.     

1×3多模干涉型光功分器的研究

本文采用导模传输分析法,在GaAs/GaAlAs单异质结外延材料上设计了1×3MMI（多模干涉）型光功分器。根据所确定的器件结构参数,结合器件设计和制作过程中可能遇到的因素,详细分析了器件中自映像效应多模波导的宽度和长度、输入单模波导的宽度等结构参数对器件性能的影响。本文基于RSoft软件,对所设计的器件结构参量进行了仿真。模拟结果表明,所设计的器件实现了1×3光功分器功能,具有插入损耗低和均匀性好的特点。     

Multimode interference-based photonic crystal waveguide power splitter

A compact power splitter based on the multimode interference (MMI) effect in photonic crystal waveguides is designed and analyzed. The device size reduction compared with the conventional MMI power splitter can be attributed to the large dispersion of the photonic crystal waveguides. The Massachusetts Institute of Technology Photonic-Bands code is used to calculate the band structures of photonic crystal waveguides. The finite-difference time-domain method is adopted to simulate the relevant structures.     

质子交换铌酸锂波导MMI光功分器

利用三维非旁轴近似光束传输法对退火质子交换铌酸锂渐变折射率分布波导中的自镜像效应进行分析与模拟.在此基础上,利用退火质子交换技术在X切Y传铌酸锂衬底上进一步制作了1×8 MMI光功分器.测试表明器件实现了1路分成8路的光功分功能.     

一种紧缩型的SOI 3-dB多模干涉耦合器

采用线锥形结构,在silicon-on-insulator (SOI)材料上设计并实现了一种新的紧缩型3-dB多模干涉耦合器(MMI).与普通的矩形结构3-dB MMI耦合器相比,该器件长度减少了40%.耦合器输出均衡度为1.3dB,过剩损耗为2.5dB.     

Wideband Criterion for Multimode Interference Splitters

A wideband criterion for multimode interference (MMI) splitter is proposed. The basic principle is based on reducing the interference length difference and making it shorter than the spot size for constructive mode interference. Simulation results show the spectra of proposed MMI splitter is wide enough (1.26-1.70 mum) to cover the fiber communication band and the size of the splitter is more compact than that of the conventional MMI or Y-branch splitter     

可调谐高分子MMI光波导功率分配器的研究

设计了一种基于多模干涉(MMI)波导结构的可调谐功率分配器,利用高分子含氟聚酰亚氨材料的热光效应,调节多模波导中局部区域的折射率,可实现两单模输出导模的输出功率比在较大范围内连续可调谐.BPM防真证实了这一结果.     

Analysis of generalized Mach-Zehnder interferometers forvariable-ratio power splitting and optimized switching

The nonideal integrated optical N×N generalized Mach-Zehnder interferometer (GMZI) employing multimode interference (MMI) couplers is analyzed using transfer matrix techniques. Deviations in the phase relations and the power splitting ratio of the MMI couplers are included in the theory, along with the effects of phase errors in the interferometer arms. The predictions of the theory are compared to the response of a 4×4 GMZI which has been fabricated. The device is operated as both a variable-ratio power splitter and a switch by compensating for the phase errors in the interferometer arms, but the performance is ultimately limited by the nonideal imaging in the MMI couplers. The practicality of these applications is investigated by performing a tolerance analysis for the operation of 1×N power splitters and switches for N up to 10     

Optimal design of a multi-mode interference splitter based on SOI

In this paper, the multimode waveguide lengths and the output port locations of a SOI （silicon on insulator） material-based 1×4 MMI （multimode interference） optical splitter are optimized by means of FD-BPM （finite difference - beam propagation method）. An improved 1×4 MMI optical splitter is designed. Compared with an usual optical splitter, a smaller loss 0. 12dB and a better output port power uniformity 0.11dB are achieved for the optical signal transmission.     

Shortened Polarization Beam Splitters With Two Cascaded Multimode Interference Sections

This letter presents a design for shortening the length of a polarization beam splitter (PBS) by using two cascaded multimode interference (MMI) sections with different widths. By optimizing the MMI parameters, a short PBS of good performance is achieved. The total length of the PBS is reduced to about 1/28 of that of a conventional design.      

A 12-channel phased-array wavelength multiplexer with multimodeinterference couplers

A compact 12-channel phased-array wavelength-division multiplexer based on multimode interference (MMI) couplers and useful for application with multiwavelength lasers is proposed. A suitably-chosen 1×12 MMI nonuniform power splitter is used to suppress the sidelobes of the multiplexer spectral response. Simulated results for the multiplexer designed in an InP-InGaAsP rib waveguide system and with 1-nm channel spacing at a wavelength of 1550 nm are presented. The multiplexer has a length of 3.2 mm and an insertion loss of 1.7 dB     

Proposal for an Ultracompact Polarization-Beam Splitter Based on a Photonic-Crystal-Assisted Multimode Interference Coupler

An ultracompact polarization-beam splitter (PBS) combining a multimode interference (MMI) coupler and some photonic crystal (PC) structures is presented. The MMI coupler is designed to collect polarized powers reflected by or transmitted through an internal PC structure. The simulation result shows that the designed PBS is very short (about 50 mum), and has a low insertion loss, a high extinction ratio, and a broad bandwidth     

硅基槽波导级联多模干涉耦合器型偏振分束器

提出了一种基于硅基槽波导的级联多模干涉(MMI)耦合器型偏振分束器,由锥形及矩形结构MMI耦合器构成.级联结构使器件长度无需为两偏振模自镜像长度的公倍数,不仅能有效减小器件尺寸,而且提高设计灵活性.同时,利用槽波导的高双折射特性及MMI耦合器的锥形结构,可进一步缩短器件尺寸.分析结果表明,所提器件能够有效实现偏振束分离,两级MMI工作区总长度仅为42μm,准TE与准TM模的偏振消光比分别为29.8和31.4d B,1.55μm波长下的插入损耗分别为0.395和0.699 d B,偏振消光比大于20 d B时光带宽为43 nm,覆盖整个C波段.最后,详细分析了器件关键参数的制造误差对器件性能的影响.     

Theoretical Investigation of Polarization-Insensitive Multimode Interference Splitters on Silicon-on-Insulator

An ultracompact polarization-insensitive 1times2 multimode interference (MMI) splitter based on silicon-on-insulator is investigated theoretically. The impact of the insulator index on the size of the MMI and the polarization-dependent performance is analyzed. A polarization-insensitive 1times2 MMI splitter of 4 mum by 16.5 mum is shown as an example. Relaxed tolerances on MMI width (> plusmn100 nm) and length (> plusmn0.7 mum) are obtained for both polarizations while the polarization differential loss is kept in range of 0.1 dB and its excess loss is kept below 0.5 dB. In addition, a wide operation wavelength window of 150 nm is obtained for both polarizations as well.     

An InP-based optical multiplexer for 100-GHz pulse-train generation

A 100-GHz optical pulse train is generated using an InP-based optical multiplexer. This device is based on a waveguide array with five paths of different lengths separated by a 10-ps propagation time. We used a multimode interference (MMI) splitter at the input and a taper-type combiner at the output. This device is well-suited for optical time-division multiplexing (OTDM) applications     

蝶形多模干涉耦合器的数值分析

设计蝶形多模干涉(MMI)耦合器时,需要根据所要求的功率分割比率确定器件的结构参量。作为矩形多模干涉耦合器的特征参量的耦合长度,通过数值分析对称干涉型矩形多模干涉耦合器的成像位置而得到,从而可利用模传输分析(MPA)法的公式设计出蝶形多模干涉耦合器的理论预期结构。使用有限差分波束传输法(FD-BPM)对设计参量进行校正,并且数值算出器件实际实现的功率分割比率。针对基于SOI晶片的设计实例表明,仿真得到的蝶形多模干涉耦合器的长度较理论预期大2～4 μm,实际实现的功率分割比率较理论预期值低且器件形状越偏离矩形,其值相差越大。     

Design and performance evaluation of 1-by-64 multimode interferencepower splitter for optical communications

A 1-by-64 multimode interference power splitter in SiO₂ has been designed for use in fiber-optics communication systems. The splitter exhibits a minimum loss of 0.5 db and a uniformity of 1.7 dB at a wavelength of 1.55 μm. The polarization sensitivity is below 0.14 dB, the reflection level below -55 dB, and the optical bandwidth 30 nm. The fabrication tolerances are ±0.1 mm on the length and ±3.5 μm on the width of the multimode section of the splitter. In comparison with a branching-type splitter it is found that the designed device is approximately 30% shorter than the branching-type device for comparable losses     

Experimental demonstration of all-optical regeneration using anMMI-SOA

A novel all-optical 2R regenerator based on a multimode interference coupler (MMI) semiconductor optical amplifier is presented. Static measurements of the transfer function reveal a digital transfer characteristic and a high increase in extinction ratio. The experiments are in good agreement with simulations, which have been done using a modified beam propagation method program. The device has a high tolerance to the MMI length. It has been fabricated in an all-active layout, avoiding the need for active/passive integration and is very compact     

采用多模输入/输出波导的多模干涉型SOI分束器

一个适用于光纤通信系统中的1×8多模干涉功率分束器被设计并通过ICP刻蚀方法成功研制.这种基于SOI材料的功率分束器是采用多模波导作为输入/输出波导;经过光束传播方法模拟,该器件显示出了优良的性能.测试结果表明,在1550nm波长处器件的传波损耗低于0.80dB,损耗均匀性为0.45dB,而且偏振相关损耗低于0.70dB.器件的尺寸只有2mm×10mm.     

Reduced reflections from multimode interference couplers

A 3 dB multimode interference (MMI) coupler optimised for low reflections is presented. The MMI was designed, fabricated and characterised. For comparison, MMIs with non-optimised layout have been included on the same sample. The measurement results show a reduction in reflectivities of more than 10 dB.