Design,modelling and implementation of the ATMOS project fibre delay line photonic switching matrix

This paper presents the fibre delay line switching matrix, a high-performance photonic system consisting of an electrically controlled optical high-speed transport network. This photonic matrix adopts the asynchronous transfer mode (ATM) technique and an internal self-routing architecture based on wavelength encoding, for cell routing and multiplexing. A set of output queues provides the buffering function.An extensive performance evaluation is presented, with reference to both the traffic throughput and technology feasibility. Numerical results have been obtained to evaluate optical performance and the implementation of a 4×4 demonstrator, supporting a 2.5 Gbit s^-1 input/output rate, shows the feasibility of the matrix with state-of-the-art optical technology.Its high performance makes the fibre delay line switching matrix a strong candidate for implementing the core of future high-speed broadband ATM switches.     

DFB lasers with integrated electroabsorption modulator

We present high-performance 1550 nm DFB lasers with butt-coupled, bulk type integrated electroabsorption modulators of good manufacturability and reliability. Key issues in device design are reviewed and the strong influence of the exact detuning between lasing wavelength and modulator bandgap is demonstrated. Fibre-coupled output powers as large as 6 dBm and attenuation efficiencies as high as 12 dB V^–1 are obtained. Butterfly-packaged devices show only 1 dB penalty for 10 Gbit s^–1 NRZ transmission over 50-km standard single-mode fibre (SMF) without the use of an optical amplifier. With an optical booster amplifier, self-phase-modulation in the fibre is exploited and repeaterless 10 Gbit s^–1 transmission is possible over 150-km standard SMF.     

Optical receiver design with high sensitivity and high dynamic range using feedback and lossy noise-matching network

A new type of optical receiver design providing high sensitivity and high dynamic range is presented that employs a lossy noise-matching network and feedback type amplifier. The design is based on the noise figure concept using the four noise parameters of FET, which makes it easy to design multigigabit opical receivers by combining it with microwave CAD tools. The effects of matching network element value and group delay variation of the preamplifier on receiver sensitivities are addressed. The predicted receiver sensitivity including the effect of group delay is -27.1 dBm, which is the highest sensitivity for a 10 Gbit s^-1 PIN-FET optical receiver reported to date.     

Bit-error rate evaluation for non-linear propagation in optical fibres

The influence of soliton time jitter on the bit-error rate in long-distance single-mode optical fibre transmission lines was studied. It was assumed that mutual interactions between two adjacent solitons were prevented by periodic amplification. It was found that the upper bit rate bound of practically acceptable non-linear transmission is about 50 Gbit s^–1. Above a bit rate of 50 Gbit s^–1 the advantage of non-linear (soliton) transmission, related to dispersion-free linear transmission, disappears.     

具有旋转连接功能的双层光互连网络设计

在设计的双层光互连网络中,上层网络是星型连接,依靠数字路由结点进行通信.单通道最大传输速率为1.4 Gbps,数字路由结点吞吐率大于10 Gbps,底层为网络接口卡和结点机连成的环形网,峰值传输速率为1.056 Gbps.在底层网络中个别结点机与传感器之间配置有光纤旋转连接器,可传输动态数据.经计算,环网内最大通信延迟时间小于5.292 μs,互连网络的平均通信延迟时间为11.03 μs,环形网络的最大数据传输带宽为50 Mbit/s.     

A novel approach to all-optical wavelength conversion by utilizing a reflective semiconductor optical amplifier in a co-propagation scheme

Nonlinear optical gain modulation in an InGaAsP/InP bulk reflective semiconductor optical amplifier (RSOA) is studied. The differences of the optical properties between RSOAs and conventional SOAs are initially investigated. All-optical wavelength conversion based on nonlinear gain modulation in RSOAs is demonstrated at a bit rate of 2.488 Gbit/s. It is shown that a bit-error-rate of <10⁻⁹ can be achieved and an extinction ratio of >9 dB can be obtained at a bit rate of 2.488 Gbit/s with a 2³¹-1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). In comparison with conventional SOAs, wavelength conversion by RSOAs shows much improved performances in high-speed all-optical wavelength conversions.     

Design and demonstration of a novel optical CDMA platform for use in avionics applications

We designed, built, and demonstrated a highly scalable incoherent optical CDMA platform under DARPA contract which was delivered to Lockheed Martin for additional testing in avionic applications. The platform enables users to communicate with each other at ∼1.25 Gbit/s per user with raw BER of less than 10⁻¹². The system architecture uses (3, 11) fast wavelength-hopping, time-spreading prime codes with a chip size of 73 ps utilizing picosecond optical pulses allocated in the time and wavelength domains. A novel design of a “dual code” optical encoder and decoder realized a novel optical layer implementation of an XOR gate and enabled secure network connectivity using a “One-time pad” encryption approach. The testbed is also designed to conduct eavesdropping studies on testbed users. The incoherent OCDMA approach is compatible with existing DWDM optical networks and uses off-the-shelf components.     

The reconfigurable dispersion compensator based on LNOI waveguide grating

In this paper, we propose a novel reconfigurable optical dispersion compensator achieved by waveguide grating and electro-optic effect of lithium niobate on insulator. Reconfigurable compensation is attained by controlling the voltage of the electrodes on waveguide grating. The measured bit error rate in the system is below 10^?10 in a 40 Gbit/s quadrature phase shift keying transmission system.     

All-optical implementations for high-capacity TDMA networks

In this article we show how optical technology can allow the design of new optical devices that are able to perform some network functions in order to treat very high bit rate signals (100 Gbit/s). The multiplexing technique that we take into account is the Time Division Multiple Access (TDMA), and the network functions we consider are multiplexing, demultiplexing, synchronization, packet decoding, routing, and resolution of packet contention.

In order to show how these new optical devices can improve the network performance we propose two different network topologies: the first concerns a TDMA star network where the signal information is simultaneously broadcast to all users, while the second is a multihop network. The former is useful mainly for circuit switching, while the latter is suitable for packet switching.

Soliton propagation is used in order to avoid the problem of fiber chromatic dispersion.     

1 Gbit/s transmission over step-index plastic optical fiber using an optical receiver with an integrated equalizer

A single chip optical receiver with an integrated large-diameter photodiode, transimpedance amplifier, two stages active equalizer, post amplifier and 50 Ω driver is used for gigabit transmission over PMMA step plastic optical fiber (SI-POF). The large-diameter photodiode with an antireflection coating optimized for red light. The integrated equalizer enables the presented optical receiver to reach 1 Gbit/s over 50 m SI-POF at bit error ratio of 10^− 6. An error free (< 10^− 9) 1 Gbit/s data rate over 40 m standard PMMA step-index plastic optical fiber is also achieved.     

NRZ to Manchester code conversion based on nonlinear optical fiber loop mirror

An approach to convert NRZ signal to Manchester code at 20 Gbit/s based on nonlinear optical fiber loop mirror (NOLM) is demonstrated. Using 20 Gbit/s NRZ data and optical clock as external pumps of the NOLM, the conversion of NRZ to Manchester code is successfully realized. The eye diagrams, waveforms and optical spectra are presented. We investigated the extinction ratio (ER) penalty (5 dB) to evaluate the system performance and analyzed the method to improve it. The proposed scheme is potential for applications in future networks.     

Performance improvement and wavelength reuse in millimeter-wave radio-over-fiber links incorporating all-fiber optical interleaver

Simultaneous downlink performance improvement and uplink wavelength reuse in a full-duplex millimeter-wave (MMW) radio-over-fiber (RoF) system by using a simple and cost-effective all-fiber optical interleaver are proposed and demonstrated. The MMW RoF downlink performance improvement is based on suppressing optical carrier-to-sideband ratio (OCSR), with which the mechanism is confirmed by theoretic analysis and derived experimental results. Measured results show that, by suppressing OCSR using a fabricated all-fiber optical interleaver, the downlink optical receiver sensitivity is improved about 2.1 dB. The downlink data rate is 1.25 Gbit/s and the carrier frequency is 58.1 GHz; the link consists of 6 km optical single-mode fiber and 1 m wireless connection. On the other hand, with the interleaver suppressing downlink OCSR, simultaneously an optical carrier is recovered from the RoF downlink and is reused for RoF uplink transmission. The uplink is operated at 62.9 GHz and the data rate is the same 1.25 Gbit/s. With the recovered optical carrier, a laser-free remote access point is achieved. The principle, structure, and fabrication of an all-fiber optical interleaver are also presented in this paper.     

Comparative investigation and suitability of various data formats for 10 Gb/s optical AWG multiplexer and AWG demultiplexer based transmission links

In this paper, we have analyzed the performance and feasibility for the metropolitan area network based on arrayed waveguide grating (AWG) multiplexers and arrayed waveguide grating (AWG) demultiplexers operating at the bitrate of 10 Gb/s. In the network, the data is successfully transmitted to a distance of 50 km with a very low BER of 1 × 10⁻⁴⁰ thus improving the performance over AWG star based networks. Here, we have observed that arrayed waveguide gratings based multiplexers and demultiplexers for WDM applications prove to be capable of precise multiplexing and demultiplexing of a large number of channels with relatively low losses. This paper also presents the comparative investigation and suitability of various data formats like NRZ Rectangular, NRZ Raised cosine, RZ Rectangular, RZ Raised cosine and RZ super Gaussian for optical transmission link. It has been shown that RZ Raised cosine yields the highest value of Q, good eye opening and lowest BER.     

面向LOFAR应用的160Gbit/s OTDM试验平台

报告了一个用于低频射频天线网络LOFAR的160 Gbit/s 演示平台.文章介绍了LOFAR网络结构以及用于LOFAR长臂的OTDM/WDM系统结构,回顾并探讨了用于实现160 Gbit/s系统的关键技术,并介绍了实验室中实现该160 Gbit/s OTDM/WDM演示平台所采用的技术方案。出于经济性考虑,所有的关键系统功能都采用自己搭建方案.     

Analysis of format conversion from optical 16QAM to QPSK based on cascaded four-wave mixing in semiconductor optical amplifier

A scheme of format conversion from optical 16-ary quadrature amplitude modulation (16QAM) to quadrature phase shift keying (QPSK) signal based on cascaded four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is proposed. Theoretical analysis and simulations of the format conversion scheme are conducted to validate the feasibility of the proposal. In this proposal, the phase conjugated of 16QAM signal is generated after the first FWM process in an SOA, and then the QPSK signal is converted due to the second non-degenerate FWM (ND-FWM) process in another SOA. The performance and the optimal design of the 10 Gbit/s format conversion system under various key parameters of SOAs are evaluated and discussed. Simulation results present useful to enable interconnection between backbone network and access network.     

Analysis of Transmission Performance in SUPERPONs

In this work we study how optical amplifiers can deeply improve the performance of the passive optical networks (PONs), permitting a large number of optical network units (ONUs), transmitting at high bit rate. These high-capacity networks are called SUPERPONs, and we show how to achieve a network with 8,192 ONUs with a transmission in the downstream direction up to 10 Gbit/s.     

Analysis of Transmission Performance in SUPERPONs

In this work we study how optical amplifiers can deeply improve the performance of the passive optical networks (PONs), permitting a large number of optical network units (ONUs), transmitting at high bit rate. These high-capacity networks are called SUPERPONs, and we show how to achieve a network with 8,192 ONUs with a transmission in the downstream direction up to 10 Gbit/s.     

平面波导型对称星型耦合器的优化设计

通过有限差分波束传播法(FD-BPM)研究了N×N平面波导型星型耦合器的优化设计思想和方法,并通过17×17星型耦合器的模拟设计证明了它的可行性.给出了在输出端引入辅助波导的方法,以提高输出波导阵列的均匀性.并通过模拟计算,分析了圆心缩入程度和锥形区的形状对输出结果的影响.此法也同样适合于N值更大的星型耦合器.     

Optical and electrical characterization of well-aligned ZnO rods electrodeposited on stainless steel foil

Aligned ZnO nanorods grown on polycrystalline substrates have promising optoelectronic applications. Novel samples with such structures were electrodeposited on stainless steel foil from a ZnCl₂ route. Well-aligned and free-standing hexagonal nanorods with 100-nm diameter and closely packed microrods with a diameter above 1 μm could be grown normal to the substrate. The optical transition energies (absorption and emission) of samples were determined by transmittance and photoluminescence spectroscopy. We report, for the first time, the fabrication of high-quality Ag Schottky diodes formed on the oxygen-treated (002) facets of electrodeposited microrods. Diodes with a large barrier height (1.2 eV), low saturation current density (1.3 pA/cm²) and high rectification factor (5×10⁶ at ± 3 V) were achieved. The concentration and mobility of free electrons in oxygen-treated microrods were measured as 1.4×10¹⁴ cm^-3 and 1.2 cm² V^-1 s^-1, respectively. PACS  81.15.Pq; 81.16.-c; 85.30.Kk; 81.05.Dz; 78.55.Et     

Single-Longitude-Mode Fiber Laser Implementation by Using Only Two Subring Cavities in Serial/Parallel Connection

ABSTRACT

By incorporating double-ring cavities and a piece of un-pumped Er³⁺-doped fiber (EDF) as a saturable absorber, we report a single-longitude-mode EDF fiber laser at C-band. The single-longitude-mode is obtained, the first time, by inserting only two subring cavities in either serial connection or parallel connection. The fiber laser has an optical signal-to-noise-ratio of 34.5 dB and a maximum power fluctuation of less than 1.3% for 1-hr operation. It was then modulated up to 10 Gbit/s by using an electro-optic modulator for eye diagrams, compared to back-to-back transmission. Such a compact and low-cost fiber laser is potential for high-speed optical communication.