Simulación de un enlace óptico WDM (Wavelength Division Multiplexing) utilizando POFs (Polymer Optical Fiber) en el espectro de luz visible

En este proyecto se analizaron las características y el modo de operación de las fibras ópticas plásticas en un enlace óptico WDM (Wavelenght Division Multiplexing) operando en el espectro visible. Se estudiaron los componentes activos y pasivos necesarios para el enlace, como son las fuentes LED, multiplexores, filtros y acopladores. Se analizaron los efectos no lineales que se pueden presentar en la fibra óptica, y que son importantes de considerar al transmitir señales WDM. Para respaldar el análisis se simuló en MATLAB un enlace óptico en el dominio de la frecuencia utilizando fuentes LED que emiten en el espectro visible, junto con multiplexores WDM, filtros de absorción, acopladores y como medio de transmisión la Fibra Óptica Plástica (POF -Plastic Optical Fiber).

A Novel Opto Electro Mechanical Interrogation System for Measuring Wavelength Shifts in Fiber Bragg Grating (FBG) Sensors

Here, we describe a novel FBG interrogation system in which FBGs are used as both sensing and reference elements. The reference FBGs is bonded to a mechanical flexure system having a linear amplification of 1:3.5, which is actuated using a piezo-actuator by applying a 0-150V ramp. The lengths of the reference gratings decide the maximum strain that can be applied to the reference grating, which in turn decides that strain range which can be interrogated. The main advantages of the present system are the on-line measurement of the wavelength shifts, small size, good sensitivity, multiplexing capability and low cost.

Deep-etched high-density fused-silica transmission gratings with high efficiency at a wavelength of 1550 nm

We describe the design, fabrication, and excellent performance of an optimized deep-etched high-density fused-silica transmission grating for use in dense wavelength division multiplexing (DWDM) systems. The fabricated optimized transmission grating exhibits an efficiency of 87.1% at a wavelength of 1550 nm. Inductively coupled plasma-etching technology was used to fabricate the grating. The deep-etched high-density fused-silica transmission grating is suitable for use in a DWDM system because of its high efficiency, low polarization-dependent loss, parallel demultiplexing, and stable optical performance. The fabricated deep-etched high-density fused-silica transmission gratings should play an important role in DWDM systems. (c) 2006 Optical Society of America.

Highly flexible all-optical wavelength conversion at 2.488 Gbits/s using a multi-output-wavelength laser

An integrated multiwavelength grating cavity (MGC) laser fabricated by selective area regrowth is demonstrated. In addition to allowing wavelength conversion, the device can perform various important network functions such as space switching and multiplexing. The use of the device for these functions offers several advantages from a wavelength division multiplexing (WDM) network, such as flexibility, reduced component count, size, and the associated cost reduction.

Negligible penalty all-optical routing using a 12 × 12 passive InP wavelength-selective router

This work demonstrates transmission at 2.5 Gbit/s across two wavelength-division multiplexing (WDM) network nodes, constructed using counter-propagating semiconductor optical amplifier (SOA) wavelength converters and an integrated wavelength-selective router separated by 45 km of fiber, with an overall penalty of 0.6 dB. Minimal degradation of the eye diagram is evident across the whole system. Full utilization of the capacity of the router would allow an aggregate 360-Gbit/s node capacity for a WDM channel of 2.5 Gb/s.

All optical wavelength conversion at 2.488 Gbits/s using the integrated multi grating cavity (MGC) laser

A novel integrated Multi-Wavelength Grating Cavity (MGC) laser has been used for multi-channel wavelength conversion at 2.488 Gbits/s. Functions demonstrated include conversion to multiple wavelengths, WDM multiplexing and 1×4 space switching.

All optical wavelength conversion at 2.488GBits/s using the integrated multi grating cavity (MGC) laser

A novel integrated Multi-Wavelength Grating Cavity (MGC) laser has been used for multi-channel wavelength conversion at 2.488Gbits/s. Functions demonstrated include conversion to multiple wavelengths, WDM multiplexing and 1×4 space switching.

All optical mode-multiplexing using holography and multimode fiber couplers

A spatial light modulator at the transmitter is used in conjunction with a standard multimode coupler at the receiver to modally multiplex 2 × 12.5 Gb/s nonreturn-to-zero channels using direct detection over 2 km of 940 MHz OM2 fiber without electronic processing. The wavelength dependence of this technique over a 4.5 THz band is also investigated. © 2012 IEEE.

Wavelength tunable distributed Bragg reflector laser integrated with electro-absorption modulator by a combined method of selective area growth and quantum well intermixing - art. no. 68240N

Wavelength tunable electro-absorption modulated distributed Bragg reflector lasers (TEMLs) are promising light source in dense wavelength division multiplexing (DWDM) optical fiber communication system due to high modulation speed, small chirp, low drive voltage, compactness and fast wavelength tuning ability. Thus, increased the transmission capacity, the functionality and the flexibility are provided. Materials with bandgap difference as large as 250nm have been integrated on the same wafer by a combined technique of selective area growth (SAG) and quantum well intermixing (QWI), which supplies a flexible and controllable platform for the need of photonic integrated circuits (PIC). A TEML has been fabricated by this technique for the first time. The component has superior characteristics as following: threshold current of 37mA, output power of 3.5mW at 100mA injection and 0V modulator bias voltage, extinction ratio of more than 20 dB with modulator reverse voltage from 0V to 2V when coupled into a single mode fiber, and wavelength tuning range of 4.4nm covering 6 100-GHz WDM channels. A clearly open eye diagram is observed when the integrated EAM is driven with a 10-Gb/s electrical NRZ signal. A good transmission characteristic is exhibited with power penalties less than 2.2 dB at a bit error ratio (BER) of 10(-10) after 44.4 km standard fiber transmission.

Vector Mode Analysis of Ring-Core Fibers: Design Tools for Spatial Division Multiplexing

Design tools have existed for decades for standard step-index fibers, with analytical expressions for cutoff conditions as a function of core size, refractive indexes, and wavelength. We present analytical expressions for cutoff conditions for fibers with a ring-shaped propagation region. We validate our analytical expressions against numerical solutions, as well as via asymptotic analysis yielding the existing solutions for standard step-index fiber. We demonstrate the utility of our solutions for optimizing fibers supporting specific eigenmode behaviors of interest for spatial division multiplexing. In particular, we address large mode separation for orbital angular momentum modes and fibers supporting only modes with a single intensity ring.

Minimizing the Number of Optical Amplifiers Needed to Support a Multi-Wavelength Optical LAN/MAN

Optical networks based on passive star couplers and employing wavelength-division multiplexing (WDhf) have been proposed for deployment in local and metropolitan areas. Amplifiers are required in such networks to compensate for the power losses due to splitting and attenuation. However, an optical amplifier has constraints on the maximum gain and the maximum output power it can supply; thus optical amplifier placement becomes a challenging problem. The general problem of minimizing the total amplifier count, subject to the device constraints, is a mixed-integer non-linear problem. Previous studies have attacked the amplifier placement problem by adding the “artificial” constraint that all wavelengths, which are present at a particular point in a fiber, be at the same power level. In this paper, we present a method to solve the minimum amplifier- placement problem while avoiding the equally powered- wavelength constraint. We demonstrate that, by allowing signals to operate at different power levels, our method can reduce the number of amplifiers required in several small to medium-sized networks.

Virtual Topology Reconfiguration of Wavelength-routed Optical WDM Networks

The bandwidth requirements of the Internet are increasing every day and there are newer and more bandwidth-thirsty applications emerging on the horizon. Wavelength division multiplexing (WDM) is the next step towards leveraging the capabilities of the optical fiber, especially for wide-area backbone networks. The ability to switch a signal at intermediate nodes in a WDM network based on their wavelengths is known as wavelength-routing. One of the greatest advantages of using wavelength-routing WDM is the ability to create a virtual topology different from the physical topology of the underlying network. This virtual topology can be reconfigured when necessary, to improve performance. We discuss the previous work done on virtual topology design and also discuss and propose different reconfiguration algorithms applicable under different scenarios.

Integrated Intermediate Waveband and Wavelength Switching for Optical WDM Mesh Networks

As wavelength-division multiplexing (WDM) evolves towards practical applications in optical transport networks, waveband switching (WBS) has been introduced to cut down the operational costs and to reduce the complexities and sizes of network components, e.g., optical cross-connects (OXCs). This paper considers the routing, wavelength assignment and waveband assignment (RWWBA) problem in a WDM network supporting mixed waveband and wavelength switching. First, the techniques supporting waveband switching are studied, where a node architecture enabling mixed waveband and wavelength switching is proposed. Second, to solve the RWWBA problem with reduced switching costs and improved network throughput, the cost savings and call blocking probabilities along intermediate waveband-routes are analyzed. Our analysis reveals some important insights about the cost savings and call blocking probability in relation to the fiber capacity, the candidate path, and the traffic load. Third, based on our analysis, an online integrated intermediate WBS algorithm (IIWBS) is proposed. IIWBS determines the waveband switching route for a call along its candidate path according to the node connectivity, the link utilization, and the path length information. In addition, the IIWBS algorithm is adaptive to real network applications under dynamic traffic requests. Finally, our simulation results show that IIWBS outperforms a previous intermediate WBS algorithm and RWA algorithms in terms of network throughput and cost efficiency.

Least-cost Disjoint Paths with Dependent Cost Structure in Wavelength Continuous Optical WDM Networks

One of the important issues in establishing a fault tolerant connection in a wavelength division multiplexing optical network is computing a pair of disjoint working and protection paths and a free wavelength along the paths. While most of the earlier research focused only on computing disjoint paths, in this work we consider computing both disjoint paths and a free wavelength along the paths. The concept of dependent cost structure (DCS) of protection paths to enhance their resource sharing ability was proposed in our earlier work. In this work we extend the concept of DCS of protection paths to wavelength continuous networks. We formalize the problem of computing disjoint paths with DCS in wavelength continuous networks and prove that it is NP-complete. We present an iterative heuristic that uses a layered graph model to compute disjoint paths with DCS and identify a free wavelength.

Wavelength monitoring with semiconductor laser amplifiers

The semiconductor laser diodes that are typically used in applications of optical communications, when working as amplifiers, present under certain conditions optical bistability, which is characterized by abruptly switching between two different output states and an associated hysteresis cycle. This bistable behavior is strongly dependent on the frequency detuning between the frequency of the external optical signal that is injected into the semiconductor laser amplifier and its own emission frequency. This means that small changes in the wavelength of an optical signal applied to a laser amplifier causes relevant changes in the characteristics of its transfer function in terms of the power requirements to achieve bistability and the width of the hysteresis. This strong dependence in the working characteristics of semiconductor laser amplifiers on frequency detuning suggest the use of this kind of devices in optical sensing applications for optical communications, such as the detection of shifts in the emission wavelength of a laser, or detect possible interference between adjacent channels in DWDM (Dense Wavelength Division Multiplexing) optical communication networks