Compact, low-crosstalk, and low-propagation-loss quantum-well Y-branch switches

We demonstrate a quantum-well Y-branch switch designed for low crosstalk, low propagation loss, and compact size. The active waveguide core is composed of InGaAsP-InP quantum wells for reverse-bias electrorefractive switching. We achieve -20-dB crosstalk and 2-dB/cm propagation loss with a 2-mm-long switch.     

Weighted-coupling Y-branch optical switch in InGaAs/InGaAlAsquantum well electron transfer waveguides

We demonstrate the first weighted-coupling Y-branch switch in semiconductors. The active waveguide core contains an InGaAs/InGaAlAs chopped quantum well electron transfer structure which provides large voltage-controlled refractive index changes near 1.55 μm with high speed capability. We obtain polarization-independent switching over a wide operating range, from 1.52 to 1.58 μm wavelength. We show that shaping the Y-branch results in significant improvements in voltage-length product and crosstalk performance over conventional, non-shaped Y-branches. In push-pull configuration, the drive voltage requirement is only 3.5 V for a 550 μm active length switch     

基于热光效应的1×4聚合物数字光开关

提出了基于热光型聚合物的集成有S弯曲光衰减器的1×4 Y分叉数字光开关.利用开关与光纤阵列耦合用的S弯曲,将其设计成可变光衰减器,这使得器件更紧凑,并获得低串扰和大分叉角.在小于200mW的驱动功耗下,器件串扰可低至-35dB.     

Design and demonstration of weighted-coupling digital Y-branchoptical switches in InGaAs/InGaAlAs electron transfer waveguides

We have designed and demonstrated the first semiconductor digital optical switches that use weighted-coupling Y-branches. Using the beam propagation method we model both conventional Y-branches as well as weighted-coupling, shaped Y-branches with two angles. Theoretically we find that optimal shaping of the branch can provide, for the same device length, enhanced crosstalk performance and voltage efficiency. These features are confirmed by our experimental results on switches fabricated in InGaAs/InGaAlAs chopped quantum well electron transfer waveguides. In the shaped Y-branch switch, we measure a voltage-length product of 4 V-mm with single-arm drive, while that for the conventional Y-branch is 8 V-mm, With dual arm drive in the push-pull configuration, the shaped switch only requires 3.7 V for a 550 μm active length. This switch also has polarization and wavelength insensitive switching characteristics, with less than 1.0 dB variation in crosstalk over a wide operating range from 1.52 to 1.58 μm wavelength     

Low drive voltage Y-branch digital optical switch

A Y-branch digital optical switch with reduced drive voltage and low crosstalk is reported. The local full branch angle of separating waveguides is decreased from the branching point to the end of the branch.<>     

Performance and modeling of advanced Ti:LiNbO3 digitaloptical switches

High-performance Y-branch digital optical switches realized in Ti:LiNbO₃ are presented. Their switching response functions have been optimized in terms of switch voltage and crosstalk ratio. The optimization is based on analyzing different types of waveguide shaping and switching arrangements using coupled mode theory and computer simulations. Excellent switching characteristics are achieved with devices exploiting a specially shaped waveguide branch in a dilated switch arrangement. Demonstrated performances include switching voltage as low as 9 V with crosstalk suppression better than 45 dB and fiber-to-fiber losses as low as 4 dB. Polarization independence with crosstalk suppression better than 40 dB over a 1520- to 1570-nm wavelength range is achieved for any applied switch voltage greater than 18 V. These optimized digital optical switches have further demonstrated the capability to reshape electrical input signals at switching rates of several hundred megahertz     

保偏光纤环与Y波导芯片直接耦合技术研究

光纤陀螺光路结构中,Y波导器件与保偏光纤环通过尾纤熔接的方式连接形成闭合回路来敏感系统相对惯性空间的转动信息,而熔接点引入的偏振交叉耦合以及背向反射是制约光纤陀螺测量精度进一步提高的主要因素.为此,提出了一种实现保偏光纤环与Y波导芯片直接耦合的方法,并制作了两者直接耦合的敏感环光路.经实验测试,光路中Y波导器件的插入损耗典型值为2.7 dB,分光比优于48/52～52/48,偏振串音优于-30 dB,性能指标与常规的Y波导器件相当.该光路模块理论上有利于减小光纤陀螺系统噪声和提高测量精度.     

1/spl times/2 and 1/spl times/4 electrooptic switches

We describe the design, fabrication, and testing of two packaged electrooptic switches built from poled LiTaO/sub 3/ crystals. The 1/spl times/2 switch requires a driving voltage of 1200 V and exhibits insertion loss of 2.4 dB and crosstalk of -39.2 dB; the 1/spl times/4 switch exhibits insertion loss and crosstalk of 2.8 dB and -40.6 dB, respectively, and operates using a 1100-V voltage source. The maximum deflection time between the channels is 86 ns.     

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.     

Two-mode interference photonic waveguide switch

Based on the two-mode interference principle and the free-carrier plasma dispersion effect, a two-mode interference (TMI) photonic waveguide switch with double carrier injection has been designed and fabricated for application in fiber-optic communications. It consists of an input Y-branch with single-mode ridge waveguides, a TMI waveguide coupling section, and an output Y-branch with single-mode ridge waveguides. The single-mode waveguides and the two-mode waveguide are composed of a SiGe waveguide layer on a Si substrate. The width of the TMI region of the switch is two times that of the single-mode waveguide. On the top of the TMI region and one side of the TMI region, two abrupt p-n junctions are made to inject the carriers into the optical modulation region; on the other side of the TMI region, an abrupt carrier collection region is made to collect the carriers when they are forward biased, so that the double carrier injection photonic waveguide switch has the lowest injection current density. The waveguide layers are made of SiGe/Si material, and the rib waveguides are realized by reactive ion etching. The carrier injection regions and the carrier collection region are formed by ion implantation. The input and output facets of the waveguides were ground and polished by a mechanical method. The switch was characterized by using a 1310-nm InGaAsP/InP heterostructure laser diode. Its insertion loss and ON-state crosstalk were measured to be 2.74 and -15.5 dB, respectively, at a total switching current of 110 mA. The switching time is 180 ns, and the fastest switching time is up to 30 ns.     

Polarization-independent dilated InP-based space switch with lowcrosstalk

A polarization-independent dilated switch with a low crosstalk level has been realized. In this switch, the crosstalk signal is attenuated by using controllable electrooptical attenuators which do not disturb the input signal. A reverse bias of 20 V on the attenuators reduces the crosstalk value of the dilated switch from -32 dB to -40 dB. The excess loss of the total switch is about 9 dB     

4×4热光SOI波导开关阵列

设计并制作了阻塞型和完全无阻塞型4×4热光SOI(silicon-on-insulator)波导开关阵列。开关单元采用了多模干涉耦合器(MMI)-MZI(Mach-Zehnder interferometer)结构的2×2光开关。阻塞型光开关附加损耗为4.8～5.4dB,串扰为-21.8dB～-14.5dB。完全无阻塞型光开关阵列附加损耗为6.6～9.6dB,串扰为-25.8～-16.8dB。两者的消光比都在17～25dB内变化,开关单元功耗小于230mW。器件的开关时间小于3μs。功耗和开关速度都明显优于SiO2基和聚合物基的开关阵列。     

2×2多模干涉光开关的设计与制作

以多模干涉耦合器为主体,通过载流子注入效应所引起的折射率改变来调整二重像之间的相位差,当折射率下降所引起的相位改变达到π相位时完成开关功能。在AlGaAs/GaAs/AlGaAs外延材料上,利用两步湿法腐蚀工艺,实际制作了2×2光开关并进行了测试。测试结果表明,工作在1.55μm波段,当注入电流达到160mA时,完成了开关功能。     

低串扰载流子注入型光开关的设计

针对载流子注入马赫-曾德尔干涉型光开关,提出使用输出比可调的3dB耦合器,补偿相移臂上通过载流子注入实现π相位调制所产生的吸收损耗,从而降低光开关的串扰。使用传输矩阵方法计算分析了载流子注入所伴随的吸收损耗对光开关串扰的影响,同时计算了可调3dB耦合器对光开关串扰性能的改进。计算结果表明,可调3dB耦合器的引入可以有效补偿相移臂的吸收损耗,对改善光开关的串扰性能有着明显的作用。     

A New Architecture for Nonblocking Optical Switching Networks

With the current technology, all-optical networks require nonblocking switch architectures for building optical cross-connects. The crossbar switch has been widely used for building an optical cross-connect due to its simple routing algorithm and short path setup time. It is known that the crossbar suffers from huge signal loss and crosstalk. The Clos network uses a crossbar as building block and reduces switch complexity, but it does not significantly reduce signal loss and crosstalk. Although the Spanke's network eliminates the crosstalk problem, it increases the number of switching elements required considerably (to 2N ² - 2N). In this paper, we propose a new architecture for building nonblocking optical switching networks that has much lower signal loss and crosstalk than the crossbar without increasing switch complexity. Using this architecture we can build non-squared nonblocking networks that can be used as building block for the Clos network. The resulting Clos network will then have not only lower signal loss and crosstalk but also a lower switch complexity.     

Design for Y-branch waveguides with wide angle and low loss

A novel method to design Y-branch waveguides is proposed by using total internal reflection, and the optical properties areanalyzed. The simulated results show that the optical loss values of two Y-branch waveguides with the branching angles of 12° and 30° are only 0.310 dB and 0.645 dB, respectively. Compared with conventional Y-branch waveguides, the opticalperformance of the proposed ones is well improved, which has many advantages such as wide angle, low loss, simplestructure and easy for fabrication.     

A rearrangeable multichannel free-space optical switch based onmultistage network configuration

A rearrangeable 128×128-channel optical switch based on a multistage network configuration is demonstrated. The properties of optical components required for achieving up to 1000×1000-channel switches are discussed, taking into account the diffraction limit and liquid crystal light modulator (LCLM) crosstalk. An examination of the insertion loss and crosstalk properties of the switch reveals an average loss and crosstalk of 7.9 and -21.2 dB, respectively, and worst-case loss and crosstalk of 11.0 and -12.8 dB, respectively. Such low-loss and low-crosstalk properties indicate that the proposed switch structure is suitable for a large-scale rearrangeable switch     

High-Speed High-Isolation 2$, times ,$2 Fiber-Optic Switch for Wideband Radar Photonic Beamforming Controls

A new high-performance 2$, times ,$2 fiber-optic switch is designed and demonstrated for wideband radar photonic beamforming controls. The switch deploys two bulk acoustooptic deflectors (AODs) in an imaging free-space symmetric optical design that exploits image inversion control via a Dove prism to form a 2$, times ,$2 fully reversible low crosstalk noise high-speed switching structure. Experiments at the 1550-nm test wavelength show the switch to handle 0.5-W level optical input powers, $≪ {hbox{2.2-}}mu$s switching time, $≪ $2.6-dB fiber-to-fiber optical loss, better than 56-dB optical crosstalk levels, and $≪$0.2-dB polarization-dependent loss (PDL).      

Low-Loss Y-Branch Waveguides Designed by Wavefront Matching Method

In this paper, we describe the procedure for designing low-loss Y-branch waveguides by the wavefront matching (WFM) method, and report experimental results as proof of concept. The designed Y-branches were fabricated using silica-based planar lightwave circuit (PLC) technology. A Y-branch fabricated with a 0.45%-Delta waveguide exhibited a low excess loss of less than 0.2 dB over a wide wavelength range of 1250 to 1650 nm. In addition, we demonstrate that the WFM-designed Y-branches enable us to provide compact 1 times 32 splitters with an average insertion loss of 16.0 dB at a wavelength of 1550 nm. In addition, we present some experimental results obtained using samples with different Delta values, and show that our design method is more efficient for a higher Delta waveguide suitable for functional PLC devices.     

Carrier-injection type optical S3 switch withtraveling-wave amplifier

A carrier-injection-type semiconductor optical switch for photonic switching in which a traveling-wave optical amplifier is integrated in the optical single-slip structure (S³) switch to improve insertion loss and crosstalk is discussed. Preliminary experimental results are described. These results suggest that the carrier-injection-type optical S³ switch with traveling-wave amplifier has the potential to realize a small-size but large-capacity optical switch array for photonic switching