Category: WDM & Optical Network

Media Converters Provide Cost-effective Soluton

Network complexity, demanding applications, and also the growing number of devices around the network are driving network speeds and bandwidth requirements higher and forcing longer distance requirements within the LANs. However, Media Converters provide solutions to these complaints, utilizing the optical fiber if it is needed, and integrating new equipment into existing cabling infrastructure.
What is the Media Converter? Media converter can be a device that functions like a transceiver, converting the electrical signal found in copper UTP network cabling into light waves used in fiber optic cabling. It gives you seamless integration of copper and fiber, and other fiber types in Enterprise LAN networks. Media converter supports numerous protocols, data rates and media types.
Fiber optic connectivity is important when the distance between two network devices exceeds the transmission distance of copper cabling. Copper-to-fiber conversion using media converters enables two network devices with copper ports to become connected over extended distances via fiber optic cabling. Media converters provide fiber-to-fiber conversion from multimode fiber to single-mode fiber or single-mode fiber to multimode fiber, and convert a dual fiber link to single fiber using Bi-directional (BIDI) data flow. They can also convert between wavelengths for WDM applications with devices such as WDM multiplexer. Media converters are typically protocol specific and are available to guide a wide variety of network types information rates.
For example, the Fiber-To-Fiber Media Converter can offer connectivity between multimode and single-mode fiber, between different power fiber sources and between dual fiber and single-fiber. It extends a multimode network across single-mode fiber with distances as much as 140km. Within this application, two Gigabit Ethernet switches equipped with multimode fiber ports are connected by using a couple of Gigabit Fiber-To-Fiber Media Converters, which convert the multimode fiber to single-mode and let the cross country connection between the switches. Furthermore, they support conversion from one wavelength to a new with all the single mode to multimode converter or multimode to singlemode media converter. These media converters are usually protocol independent and designed for Ethernet,and TDM applications.
Media converters do a lot more than convert copper-to-fiber and convert between different fiber types. Media converters for Ethernet networks can support integrated switch technology, and offer the opportunity to perform 10/100M and 10/100/1000M rate switching. Additionally, media converters can support advanced bridge features, including VLAN, QoS prioritization, Port Access Control and Bandwidth Control – that facilitate the deployment of recent data, voice and video to get rid of users. Media converters can offer all these sophisticated switch capabilities in a, cost-effective device.
Media converters save CAPEX by enabling interconnection between existing switches, servers, routers and hubs; preserving the investment in legacy equipment. They reduce CAPEX by avoiding the necessity to install new fiber links by enabling WDM technology through wavelength conversion. Media converters also reduce network OPEX by helping troubleshoot and remotely configure network equipment that is at distant locations, not waste time and funds when there is not just a network administrator on the distant location.
Media converters are necessary to produce a more reliable and cost-effective network nowadays. So, where are we able to get high quality Media Converters with reasonable price? Visit Fiber Media Converter Solution in fiber-mart.com now.

CWDM System Testing Process

With the explosion of CWDM, it is very necessary to formulate a basic testing procedure to certifying and troubleshooting CWDM networks during installation and maintenance. Today, one of the most commonly available test methods is the use of an OTDR or power source and meter, which is capable of testing the most commonly wavelengths, 1310, 1490, 1550 and 1625nm.
This article here is based on the pre-connectorized plug and play CWDM systems that allow for connecting to test equipment in the field:
In the multiplexing module of a pre-connectorized CWDM system, wavelengths are added to the network through the filters and transmitted through the common port. The transmitted wavelengths enter the COM port in the de-multiplexing module and are dropped. All other wavelengths present at the MUX/DeMux module are went through the express port.
Most of today’s OTDRs have expanded capability for testing wavelengths in addition to 1310 and 1550 nm. The OTDR allows partial testing of such system offered in test equipment source. The OTDR allows partial testing of these systems by using the flexibility of pre-connectorized solutions. This is done by switching connections within the CWDM field terminal to allow for testing portions of the non-1310/1550 nm optical paths.
To test the 1310nm, the first step is to test the downstream portion of a system at 1310 nm by connecting the OTDR to the 1310 nm input on the CWDM MUX located at the headend. Then switch the test leads over the the upstream side and repeat. Test method is the same for both the downstream and upstream paths.
1550 nm testing is performed similarly by switching the test leads to the 1550nm ports. If additional wavelengths are present, you need to follow the procedures below:
Using the 1550 nm test wavelength, switch the OTDR connection to the 1550 nm input port on the headend MUX. Have a technician stationed at the field terminal connect the drop cable leg connectors for the 1570 nm customer to the 1550 nm port on the Mux/demux device. What should be noted is that in a play and plug solution this should not require repositioning where the drop cable passes through the OSP terminal. Test the downstream 1570 nm passive link at 1550 nm, and then repeat for the 1570 nm upstream side. When testing is complete, have the technician switch the connections for the 1570 nm drop back to the 1570 nm ports on the field MUX/DeMUX device as shown in Figure 6. Repeat this process for the 1590 nm, 1610 nm drop cables and other wavelengths present. Finally, test the 1550 nm path normally with the 1550 nm drop cable connected to the 1550nm MUX/DeMUX ports.
Since the OTDRs is able to test at 1490 or 1625 nm, the drop cables under test could be connected to the EXP port of the module and tested at 1490 or 1625 nm respective wavelength, without having to connect each to the 1550 nm port. Otherwise the procedure is the same.
As CWDM network become more and more common the data they carrying has also become critical. The procedure introduced here allows for testing modular pre-connectorized CWDM systems with standard optical test equipments. Relative channel power can be measured with a wide-band fiber optic power meter at the filter outputs or at other points in the network with the aid of a wavelength selective test device or with an optical spectrum analyzer.

MEMS Based Variable Optical Attenuators

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It is commonly known that fiber optic attenuators are used in fiber optic communications, as fiber optic tester tools to test power level margins by temporarily adding a calibrated amount of signal loss, or installed permanently to properly match transmitter and receiver levels. According to its stability, it divided into fixed fiber optic attenuators and variable optical attenuators. Variable fiber optic attenuators generally use a variable neutral density filter, with advantages of being stable, wavelength insensitive, mode insensitive, it offers a large dynamic range.
With the rapid increases in traffic on optical telecommunications systems, there is an active program for developing transmission devices for use in wavelength division multiplexing (WDM), which is becoming mainstream technology for providing higher transmission speeds and a larger number of signal channels. It has been suggested that in the WDM systems of the future, variation in power due to the wavelength could be reduced a the quality of transmission improved by adjusting the power after demultiplexing into individual signals wavelengths. It is envisaged that the current method, in which the power of all the multiplexed optical signals is adjusted by a single variable optical attenuators (VOA) would give way to a method in which one VOA is used for each wavelength. Given the number of multiplexed wavelengths, this change will require VOAs that are considerably more compact. Against this background, There have developed a VOA using micro-electromechanical system (MEMS) technology with loss characteristics that have low wavelength dependence.
Single-mode fiber was used as the input and output of the VOA developed here, with a graded index fiber having the same diameter, 125um, as the SMF fusion spliced for a specified length, to form an optical coupling with a lens function. An anti-reflection coating is applied to the tip of the GIF (graded index fiber). GIF tip is polished at an angle so that the light beam emitted from the end of the GIF is not aligned with the optical axis of the fiber, but is at an angle to it. This angled optical beam is interrupted by means of a shutter that has been formed by inductively-coupled plasma deep reactive ion etching. The MEMS chip uses a silicon-on-insulator wafer, with the shutter, actuator and fiber grooves formed simultaneously on the chip by ICP-DRIE, followed by metal vapor deposition over the whole chip.
The actuator of the MEMS chip is of the comb type, and the GIF is held in the fiber grooves by means of adhesive. The MEMS chip with this GIF optical coupling system is fixed by adhesive within a casing, which is hermetically sealed.
MEMS variable optical attenuators are variable in three different configurations. The VA series works in transmission, whereas the VP series uses reflection to modulate the attenuation. The VX series is the VP or the VA series in mint plastic packing. In terms of performance, the VP series achieves lower insertion loss and better Polarization dependent loss characteristics. Whereas the VA series allows for an easier array integration and is the lower cost.
FiberStore offers a full line of optical attenuator variable testers, they are often combined with an active system component to maintain optical power on a network even if the power changes in the input signals. Our automatical variable optical attenuators are specifically designed for use in DWDM networks with individual channel source elements such as add/drop transmitters. The cost and performance characteristics of our automatically variable optical attenuators are specifically targeted to allow for the use of these devices in volume as principal DWDM channel stabilization components.

The Application of Optical Passive Components in WDM System

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Based on the DWDM technology, the all-optical network make full use of fiber optic cables which have huge transmission capacity, it must be the next-generation high reliability, fast speed information network technology. Fiber optic attenuators are widely and important optical passive components, especially in the all-optical network.
Optical attenuator is applied into WDM system upstream and downstream node channel, power balance, EDFA gain flatness, optical communication lines, system evaluation, research and adjustments, correction and so on. It is in accordance with customers’ requirements by absorbing or reflecting off part of the optical power and then reduce the signal power as expectation. It’s position in the optical fiber network just shown in the figure.
In the WDM system, EDFA is a necessary component, it is quite important for achieving all-optical network communication. However, because of the limitation of gaining window ports for EDFA, it makes different wavelengths have different gain multiplier, it leaded to energy imbalance between the channels of a WDM sytstem. Then it will result in following three problems:
Received Energy imbalance will beyond the allowed dynamic range finally.
Accumulation of SNR imbalance can cause gain of a certain wavelength of BER, it may lower than the required BER (bit error rate).
Because of the shortage of the gain, the minimum signal power of the channel may be lower than the sensitivity of the receiver.
In the DWDM optical network which has multiple contact node, such as MAN, the transmission distances and the volume of the business between the different channels are different, each channel’s transmission must be balanced, including power, BER, signal to noise ratio and so on. The application of variable fibre optic attenuator is the first solution in the system.
Moreover, optical attenuators are also important for optical telecommunication link and the test for the system. Fiber optic cable link and the system need to be examined before laying them, then it can insure some performance parameters of the system or link road, so that it is easy to do some optimization test. So we need to simulate the actual situation, mainly the proper attenuation for the signal, then we will find out the actual situation after the long distance transmission.

How to Add CWDM MUX/DEMUX System to Your Network?

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Coarse wavelength division multiplexing (CWDM) technology is developed to expand the capacity of a fiber optic network without requiring additional fiber. In a CWDM system, CWDM Mux/Demux (multiplexer/demultiplexer) is the most important component. Usually, a CWDM Mux/Demux is used to increase the current fiber cable capacity by transmitting multiple wavelengths, typically up to 18 separate signals over one fiber. This article may mainly describe what is Mux in networking and how to install your CWDM Mux/Demux system. Unless you are an experienced user, we recommend that you follow the detailed installation steps described in the rest of this article.
Introduction to CWDM MUX/DEMUX Module
CWDM Mux/Demux module is a passive device, very reliable and simple to use. These devices are available with a variety of wavelength combinations, usually from 1270nm to 1610nm (20nm spacing). Based on different applications, a CWDM Mux/Demux module can be designed into different channels. A typical 4 channel Mux/Demux module will be used to multiplex four different wavelengths onto one fiber (shown in the picture below). This allows you to simultaneously transmit four different data over the same fiber. If you are using a CWDM multiplexer at the beginning of your network, you will use a CWDM demultiplexer at the opposite end to separate or demultiplex the wavelengths to allow them to be directed to the correct receivers. Usually, a CWDM Mux/Demux is a module that can be used as a multiplexer or demultiplexer at either end of the fiber cable span. However, it must still be used in pairs.
What IS MUX in Networking?
What is MUX in networking? A basic CWDM Mux/Demux system comprises a Local unit, the CWDM Mux/Demux module and a Remote unit. Usually, a Local or Remote unit refers to two different switches. In general, to install a CWDM Mux/Demux module, a chassis should be installed first to hold the module. Besides, to connect a CWDM Mux/Demux module to a switch, we should install CWDM SFP transceivers in the switch first. Then using the single mode patch cables to connect the transceivers to the CWDM Mux/Demux module. Therefore, when we want to build a CWDM Mux/Demux system, the components we need usually include rack-mount chassis, CWDM Mux/Demux module, CWDM SFP transceiver and single mode patch cables。
How to Add CWDM MUX/DEMUX System to Your Network?
After knowing what is MUX in networking? Next, we’ll learn how to install a CWDM Mux/Demux system, there are four basic steps:
Install the Rack-Mount Chassis
The CWDM rack-mount chassis can be mounted in a standard 19-inch cabinet or rack. When to attach the chassis to a standard 19-inch rack, ensure that you install the rack-mount chassis in the same rack or an adjacent rack to your system so that you can connect all the cables between your CWDM Mux/Demux modules and the CWDM SFP transceivers in your system.
To insert a module, you should align the module with the chassis shelf (shown in the figure below) first and then gently push the module into the shelf cavity. Finally, tighten the captive screws.
Connect the CWDM Mux/Demux to Switch
After inserting the CWDM SFP transceiver into the switch, then we should use the single mode patch cable to connect the transceiver to the CWDM Mux/Demux.
Connect the CWDM MUX/DEMUX Pairs
Once you use a CWDM multiplexer on one end of your networks, you must use a demultiplexer on the other end of the networks. Therefore, the last step to complete CWDM Mux/Demux system is to connect the Mux/Demux pairs (or multiplexer and demultiplexer). For duplex Mux/Demux, a pair of single mode patch cables must be used. For simplex Mux/Demux, only one single mode patch cable is enough. After all done, your CWDM Mux/Demux system is then installed successfully.
Conclusion
What is MUX in networking? In summary, Mux/Demux system is a cost-effective solution which is easy to install. CWDM Mux/Demux, CWDM multiplexer only, and CWDM demultiplexer only are a flexible, low-cost solution that enables the expansion of existing fiber capacity and let operators make full of use of available fiber bandwidth in local loop and enterprise architectures. Fiberstore CWDM Mux/Demux is a universal device capable of multiplex multiple CWDM (1270~1610nm) up to 18 channels (2, 4, 5, 8, 9, 16, 18 channels are available) or optical signals into a fiber pair or single fiber. Together with our CWDM transceivers or the wavelength converters, the bandwidth of the fiber can be utilized in a cost-effective way.

What Is WDM?

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WDM is a technique in fiber optic transmission that enables the use of multiple light wavelengths (or colors) to send data over the same medium. Two or more colors of light can travel on one fiber and several signals can be transmitted in an optical waveguide at differing wavelengths.
Early fiber optic transmission systems put information onto strands of glass through simple pulses of light. A light was flashed on and off to represent digital ones and zeros. The actual light could be of almost any wavelength—from roughly 670 nanometers to 1550 nanometers.
WDM is a technique in fiber optic transmission for using multiple light wavelengths to send data over the same medium.
During the 1980s, fiber optic data communications modems used low-cost LEDs to put near-infrared pulses onto low-cost fiber. As the need for information increased, so did the need for bandwidth. Early SONET systems used 1310 nanometer lasers to deliver 155 Mb/s data streams over very long distances.
But this capacity was quickly exhausted. Advances in optoelectronic components allowed the design of systems that simultaneously transmitted multiple wavelengths of light over a single fiber. Multiple high-bit rate data streams of 2.5 Gb/s, 10 Gb/s and, more recently, 40 Gb/s, 100 Gb/s, and 200 Gb/s could be multiplexed through divisions of several wavelengths. Thus, WDM was born.
There are two types of WDM today:
Coarse WDM (CWDM): WDM systems with fewer than eight active wavelengths per fiber. CWDM is defined by wavelengths. DWDM (see below) is defined in terms of frequencies. DWDM’s tighter wavelength spacing fits more channels onto a single fiber, but cost more to implement and operate.
CWDM is for short-range communications, so it employs wide-range frequencies with wavelengths spread far apart. Standardized channel spacing permits room for wavelength drift as lasers heat up and cool down during operation. CWDM is a compact and cost-effective option when spectral efficiency is not an important requirement.
Dense WDM (DWDM): DWDM is for systems with more than eight active wavelengths per fiber. DWDM dices spectrum finely, fitting 40-plus channels into the same frequency range used for two CWDM channels.
DWDM is designed for long-haul transmission, with wavelengths packed tightly together. Vendors have found various techniques for cramming 40, 88, 96, or 120 wavelengths of fixed spacing into a fiber. When boosted by Erbium Doped-Fiber Amplifiers (EDFAs)—a performance enhancer for high-speed communications—these systems can work over thousands of kilometers. For robust operation of a system with densely packed channels, high-precision filters are required to peel away a specific wavelength without interfering with neighboring wavelengths. DWDM systems must also use precision lasers that operate at a constant temperature to keep channels on target.
Ciena’s 6500 Packet-Optical Platform converges packet, Optical Transport Networks (OTNs), and flexible WaveLogic Photonics in a single platform to streamline operations and optimize footprint, power, and capacity. Built for efficient network scaling from the access to the backbone core, it offers the full gamut of CWDM and DWDM solutions, with DWDM solutions ranging from 10 Gb/s to beyond 200 Gb/s.
The 6500 has the following advantages:
Industry-leading 10G, 40G, 100G, and 200G coherent and control plane capabilities for scale and service differentiation
Hybrid OTN and packet-switching technologies for the most efficient use of network resources
Embedded and discrete software tools that increase programmability, visibility, and control of the optical network
Minimal equipment needed to adapt to a wide variety of requirements, reducing standardization and operational costs
The ability to tailor customer solutions via various chassis, power, and configuration options to maximize operational efficiencies