双向波长上下路光分插复用器

通过对科技文献的归纳总结和分析比较,介绍了四种实现双向波长上下路的光分插复用器结构和工作原理,它们是：（1）基于FBG和多口光环形器;（2）基于波导光栅路由器和FBG;（3）基于阵列波导光栅（AWG）;（4）基于解复用器／复用器对和光开关的OADM结构。     

Design considerations in optical add/drop multiplexers based ongrating-assisted null couplers

The performance of a fully optimized optical add/drop multiplexer (OADM), based on null couplers and tilted Bragg gratings, is studied in detail. It is shown that maximization of the device performance involves three main optimization steps. First, the waveguide asymmetry (V₂ /V₁ ratio) should be optimized in order to minimize the extinction ratio of the unwanted mode at the null coupler waist. Second, the coupler taper shape should he optimized in order to further minimize the aforementioned extinction ratio. Third, the grating tilt angle and relative width can be also optimized to give negligible backreflections at the input port and minimize radiation losses. The results show that the proposed high-performance OADM configuration can meet stringent telecom specifications     

Thermooptic planar polymer Bragg grating OADMs with broad tuningrange

Tunable optical add/drop multiplexers (OADMs) were achieved by combining thermally tunable planar polymer Bragg gratings with optical circulators. The gratings exhibit better than 45-dB reflection with no detectable out-of-band reflection. Apodization was utilized to achieve strong sidelobe suppression, and symmetric gratings with uniform strength across the core and cladding layers were used to minimize coupling to cladding modes. These OADMs have a high-bandwidth utilization (BWU) factor of 0.92, with a minimum channel spacing of 75 GHz. They are tunable at a rate of -0.256 nm/°C. Tuning over a 20-nm range was demonstrated with a single device     

Reconfigurable OADM and OXC designed by a new optical switch

A new dynamically selective optical add/drop multiplexer (OADM) and optical cross-connect (OXC) configuration for dense wavelength division multiplexed (DWDM) networks are proposed. The selective devices are based on fiber Bragg gratings (FBGs), single-sided micro-mirror optical switches (OSWs), and optical circulators (OCs). They are flexible, expandable, and high capacity in DWDM networks if the basic units are cascaded in series. In this paper, fiber collimators in coupling are analyzed in order to characterize the insertion loss and output power equalization in OADM and OXC. “Off-the-shelf” DWDM communication products are used for analysis; as a result, the main insertion loss in the system comes from circulators while the maximum insertion loss deviation comes mainly from FBGs and micro-mirrors. As compared to the other existing reconfigurable OADMs and OXCs, the number of mirrors in the optical switch could be dramatically reduced. The reliability of optical switch operation, therefore, can be enhanced.     

Optical add-drop multiplexers with low crosstalk

We propose and demonstrate three new optical add-drop multiplexer (OADM) architectures with simple and compact configuration and excellent crosstalk performance. The OADMs use a single multiport optical circulator and either one or two narrow-band fiber Bragg gratings, depending on the crosstalk requirement     

Study of Multichannel Parallel Anti-Symmetric Waveguide Bragg Gratings for Telecom Applications

We theoretically demonstrate the viability of parallel anti-symmetric waveguide Bragg gratings within a two-mode waveguide. These gratings produce reflections with mode conversions. This is the functional equivalent of superimposed Bragg gratings in silica-on-silicon without requiring multilevel etches. Also, due to their weaker coupling constant, these gratings allow for devices with narrow spectral full-width at half-maximum that can process multiple wavelength channels for applications such as optical add-drop multiplexers and optical encoders in optical communication systems     

基于磁调谐光纤Bragg光栅的全光纤型多路分/插复用器

提出了一种新型的用作多信道切换的光分／插复用器,它由多个可调谐光纤Ｂｒａｇｇ光栅、一对光纤环行器、ＷＤＭ复用器和解复用器构成。讨论了该分／插复用器的结构、性能和特点。利用磁极间磁场力使光纤光栅产生显著的波称偏移。用可编程磁极来调控光栅的波长偏移。其信道波长调谐速度快,装置无需外加能源即可保护信道波长的偏移。     

Reconfigurable multichannel optical add-drop multiplexersincorporating eight-port optical circulators and fiber Bragg gratings

We propose and demonstrate two new strictly nonblocking reconfigurable multichannel optical add-drop multiplexers (RM-OADMs) using optical circulators and fiber Bragg gratings. By effectively using eight-port optical circulators, the new structures significantly reduce component count and insertion loss, and achieve good crosstalk performance. One of the new RM-OADMs potentially achieves the lowest insertion loss among existing RM-OADMs     

Synthesized Structure of Amplitude—sampled FBG by Simple Inverse FT Technology and Its Application

Using the simple inverse Fourier transformation(FT), the index modulation structure with the sampled period for the sampled fiber Bragg gratings was designed. In this method, the enable channels are operated at identical wavelength while the unable channels are almost suppressed completely. The enable and unable channels can be established based on the applications. This technique is very useful to design the optical devices such as optical add and drop multiplexers (OADMs), and interleavers with dispersion and dispersion slope compensation.     

Metropolitan DWDM: a dynamically configurable ring for the KomNetfield trial in Berlin

We present the system concept of a dynamically configurable all-optical add/drop multiplexer for metropolitan wavelength division multiplex rings using dense channel spacing (DWDM). We first outline the essential network requirements. Subsequently, an optical system concept is presented that meets these requirements. In the network elements, innovative all-optical switching technology is employed. Tunable fiber Bragg gratings that perform routing functions by wavelength filtering are discussed in more detail. The system is laboratory-tested. It has been installed in Berlin for a multi-vendor field trial within the German research program “KomNet.” Three optical add/drop multiplexers form a dynamically configurable Metro DWDM ring. Metro DWDM accommodates high bandwidths: a metropolitan ring that provides 0.8 terabit/s ring capacity has been demonstrated. Furthermore, Metro DWDM can provide optically transparent channels enabling the transport of various data formats simultaneously, e.g., SONET/SDH and Gigabit Ethernet. Conversion to a standard format becomes obsolete. The all-optical add/drop multiplexer (OADM) presented provides both manual and dynamic configuration. The system concept of the OADM is developed starting with basic metropolitan DWDM network requirements. The features of the DWDM ring are described, followed by a presentation of the system concept of the flexible OADM. Our focus is on dynamic configuration techniques. Since tunable fiber Bragg gratings are promising components for dynamic optical channel switching, this technology is treated in more detail     

High extinction guided-wave optical polarization splitter

Conventional guided-wave optical polarization splitters exhibit poor polarization extinction characteristics because of the necessity of controlling waveguide parameters. In order to improve the characteristics, an electrical control scheme was investigated in an alternating Δβ directional coupler. Polarization-dependent electrooptic as well as polarization-independent plasma effects were employed to produce high extinction for two orthogonal polarizations independently. As a result, an extinction ratio as high as 32 dB was obtained with a fabricated GaAs-GaAlAs device. This is the highest value ever reported with a channel waveguide device     

Integrated three channel laser and optical multiplexer fornarrowband wavelength division multiplexing

The fabrication and characterisation of a monolithically integrated three channel narrowband wavelength multiplexer and DBR laser are reported. The multiplexers include Bragg gratings with an extinction ratio of >20 dB and a bandwidth of ~1 nm to give channel spacings of <10 nm     

Integrated multichannel OADMs using polymer Bragg grating MZIs

We report the first fabrication of Bragg-grating-based multichannel optical add/drop multiplexers (OADMs) in planar polymers. The filters were designed by cascading multiple stages of single-channel multi-/demultiplexers. Each stage consists of a Mach-Zehnder interferometer (MZI) with a Bragg grating across its arms. The 3-dB couplers in each MZI are multimode interference (MMI) couplers. We fabricated the first tapered MMI couplers, which provide compactness. The gratings were printed photochemically, achieving index differences as high as 10^-3 and reflectivities as large as 33 dB. The 3-dB bandwidth is about 0.2 nm. Apodization was used to reduce sidelobes in the reflection spectrum. Four-channel OADMs were produced and exhibited the proper 400-GHz channel separation and ITU grid wavelength alignment, as well as excellent channel isolation and uniform channel response     

Wavelength and Waveband Assignment for Ring Networks Based on Parallel Multi‐granularity Hierarchical OADMs

In this paper we study the optimization issues of ring networks employing novel parallel multi‐granularity hierarchical optical add‐drop multiplexers (OADMs). In particular, we attempt to minimize the number of control elements for the off‐line case. We present an integer linear programming formulation to obtain the lower bound in optimization, and propose an efficient heuristic algorithm called global bandwidth resource assignment that is suitable for the design of large‐scale OADM networks.     

Fabrication of ultra high aspect ratio Bragg gratings for optical filter

In this paper a novel process for fabrication of high finesse and large spectral range integrated optics filtering structure for optical communication applications is presented.The technology approach used in the fabrication make use of glass-on-silicon substrates and comprise deep submicron ultra-high aspect ratio Bragg gratings which are deeply buried into the waveguide glass materials.     

基于MZI和取样光栅的可调谐光分插复用器

提出一种基于马赫-曾德尔干涉仪(MZI)和取样光纤布拉格光栅(SFBG)的新型光分插复用器(OADM),它由两个并联马赫-曾德尔干涉仪和四个取样光纤布拉格光栅组成.对该光分插复用器的输出特性进行了理论仿真,研究得出通道间隔为0.8nm时下载和输出端口的光谱特性,研究发现干涉仪的臂长差和取样光栅的中心波长差是决定光分插复用器输出特性的主要因素.调节一个马赫-曾德尔干涉仪上的臂长差和取样光栅的中心波长,可以实现信号下载可调功能或直通功能.     

Optical add-drop multiplexers based on autocloned photonic crystals

We describe and demonstrate the operation of optical add-drop multiplexers (OADMs) based on photonic crystal (PC) structures fabricated by autocloning technology. In these OADMs, a three-dimensional PC structure was utilized as a Bragg reflector. We obtained a drop bandwidth of 2 nm at a wavelength of 1560 nm. We also demonstrate for the first time add and drop operations of the PC-based OADMs in a wavelength-division multiplexing optical transmission system.     

A novel polarizer based on directional coupler and surface plasmon polaritons

A novel polarizer with a silver nanoribbon added into a traditional waveguide directional coupler is designed to realize the polarized output of TE mode. A high extinction ratio can be obtained because of the selectivity of surface plasmon polaritons （SPPs） on polarization. The effects of the polarizer parameters on coupling efficiency and extinction ratio are discussed. Simulation results indicate that the coupling efficiency for TE mode can reach about 95%, but only 3% for TM mode, with the extinction ratio of TE mode about 15 dB when the light wavelength is 1550 nm, The polarizer may have potential applications in photonic integrated circuits and quantum information technology.     

Fiber-grating add–drop reconfigurable multiplexer with multichannel using in bi-directional optical network

A bi-directional reconfigurable scheme of multichannel-selective optical add–drop multiplexer (OADM) is proposed in this paper. With only small wavelength channel tuned range, the proposal applies fiber Bragg gratings (FBGs) and multiport optical circulators (MOCs) to build a bi-direction reconfigurable OADM which can deal with full channels without the receiving signal having wavelength-interleaved. Moreover, it is easier and more flexible to extend wavelength channels by cascading additional FBGs. The magnitudes of homodyne and heterodyne crosstalks are analyzed for evaluating the performance of the proposed BOADM. Also, the power equalization of each signal in the add–drop and output ports is managed properly by implementing filters. As a result, the BOADM will be found in wide applications in dense wavelength-division multiplexing (DWDM) optical networks and in multiwavelength crossconnects (WXCs).