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Understanding WDM MUX/DEMUX Ports and Its Application

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Wavelength division multiplexing (WDM) is a commonly used technology in optical communications. It combines multiple wavelengths to transmit signals on a single fiber. To realize this process, CWDM and DWDM mux/demux are the essential part. As we all know, there are several different ports on the WDM mux and demux. This article will give a clear explanation to these ports and their applications in WDM network.
Overview of Different Ports on WDM MUX/DEMUX
Line Port
Line port, sometimes also called as common port, is the one of the must-have ports on CWDM and DWDM Mux/Demux. The outside fibers are connected to the Mux/Demux unit through this port, and they are often marked as Tx and Rx. All the WDM channels are multiplexed and demultiplexed over this port.
Channel Port
Like the line port, channel ports are another must-have ports. They transmit and receive signals on specific WDM wavelengths. CWDM Mux/Demux supports up to 18 channels from 1270nm to 1610nm with a channel space of 20nm. While DWDM Mux/Demux uses wavelengths from 1470nm to 1625nm usually with channel space of 0.8nm (100GHz) or 0.4nm (50GHz). Services or circuits can be added in any order to the Mux/Demux unit.
Monitor Port
Monitor port on CWDM and DWDM Mux/Demux offers a way to test the dB level of the signal without service interruption, which enable users the ability to monitor and troubleshoot networks. If the Mux/Demux is a sing-fiber unit, the monitor port also should be a simplex one, and vice verse.
Expansion Port
Expansion port on WDM Mux/Demux is used to add or expand more wavelengths or channels to the network. By using this port, network managers can increase the network capacity easily by connecting the expansion port with the line port of another Mux/Demux supporting different wavelengths. However, not every WDM Mux/Demux has an expansion port.
1310nm and 1550nm Port
1310nm and 1550nm are one of WDM wavelengths. Many optical transceivers, especially the CWDM and DWDM SFP/SFP+ transceiver, support long runs transmission over these two wavelengths. By connecting with the same wavelength optical transceivers, these two ports can be used to add 1310nm or 1550nm wavelengths into existing WDM networks.
Application Cases of Different Ports on WDM MUX/DEMUX
Although there are several different ports on WDM Mux/Demux, not all of them are used at the same time. Here are some examples of these functioning ports in different connections.
Summary
Different ports on the CWDM and DWDM Mux/Demux have different functions. Knowing more their function is helpful in WDM network deployment. fiber-mart.COM supplies various types of CWDM and DWDM Mux/Demux for your preference. And customer services are also available. If you have any needs, welcome to visit our website http://www.fiber-mart.com.

Things to Know About Bend Insensitive Multimode Fiber

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Bend insensitive multimode fiber (BIMMF) has become a very active area within the telecommunication industry once it was introduced and popularized. It typically signifies technical advancements in the production of multimode optical fiber for easier installation, and cable management for multimode fiber cables through improvements in bend insensitivity. This article will focus on some useful information about BIMMF from the perspective of its working principle, performance in networking and unique advantages as well.
What Is Bend Insensitivity?
An optical fiber consists of a core and a cladding. Although both of these regions are made from glass in telecommunications grade fibers, they are significantly different from each other. Each region is designed to capture light within the core and transmit it to the opposite end of the fiber. During this process, the light may follow many paths, depending on the angle at which the light hits the boundary, it is either reflected back into the core, or it gets lost into the cladding. Therefore, the light losses during transmission cause a weaker optical signal at the other end.
Optical fiber is sensitive to stress, particularly bending. When conventional fibers are bent tightly, some of the signal will leak out of the fiber at the site of the bend due to macrobend loss, which will results in system failure and unplanned downtime. Various attributes in the fiber determine when this occurs. The relative ease with which this happens is known as bend sensitivity. On the contrary, bend insensitivity is a positive feature that can provide for additional robustness and simplify installation of multimode fiber.
Introduction to Bend Insensitive Multimode Fiber (BIMMF)
Bend-insensitive multimode fiber (BIMMF) has an innovative core design that enables it to significantly reduce macrobend loss even in the most challenging bend scenarios. It is hence natural that bend insensitive multimode fiber can withstand tough treatment. The difference between traditional multimode fiber and BIMMF mainly lies in the fact that the BIMMF design can include an optical trench. This trench effectively improves the fiber’s macrobend performance by retaining more of the light that would have escaped the core of a traditional multimode fiber. So when compared with standard multimode fibers, BIMMF is proved to be a good candidate for loss and bend critical applications because of their higher immunity to bending losses, without loosing performances or compatibility to other standard high bandwidth multimode fibers.
Compatibility With Conventional Fibers
There is a lot of buzz around the issue of bend insensitive fiber— is it compatible with regular fibers? Can they be spliced or connected to other conventional fibers without problems? Modeling and testing on BIMMF has shown that an optimized BIMMF is backward compatible and can be mixed with non-BIMMF without inducing excess loss. Hence, BIMMF and MMF could easily be mixed in an optical channel without complicating the estimation of losses. Moreover, BIMMF may lead to higher tolerance to possible misalignments when two connectors are mated. This is an additional positive feature for 40 and 100 Gigabit applications.
In summary, a well-designed BIMMF complies with all relevant industry standards and adheres to the following:
BIMMF OM2, OM3 and OM4 multimode fibers are fully compliant and fully backward-compatible with all relevant industry standards.
BIMMF is fully backward-compatible and may be used with the existing installed base of 50/125um multimode grades including OM2, OM3 and OM4.
BIMMF may be spliced or connectorized to conventional 50/125um fiber types with commercially available equipment and established practices and methods, no special tools or procedures are required.
BIMMF not only meets all relevant macrobend standards, but sets a new level of bend performance.
Advantages of BIMMF
Bend insensitive multimode fiber is available in all laser optimized grades, OM2, OM3 and OM4, and exhibits 10 times less signal loss in tight bend scenarios and therefore protects enterprise and data center systems from unplanned downtime due to signal loss and associated significant revenue loss.
This fiber type offers extremely low bending loss at both the 850 and 1300 nm operating windows, while maintaining excellent long term fiber strength and reliability. The fiber can be installed in loops as small as 7.5 mm radius with less than 0.2 dB bending loss at 850 nm and 0.5 dB at 1300 nm.
In addition, bend insensitive multimode fibers enable new possibilities for cable and patch panel design to further improve the benefits of using fiber. Optical cable manufacturers can now design thinner, more flexible trunk cables, making for easier cable installation and further improving airflow in conduits, patch panels and racks. Due to the ability of the fib cable to be bent tightly with significantly less signal loss, connector modules can be made smaller which in turn leads to an increased density within racks and smaller racks.
Conclusion
Bend insensitive multimode fiber has been widely employed to enhance fiber management in data centers, high performance computing and enterprise LANs. Since it is a real advance to current standard multimode fibers, BIMMF is recommended for bend and loss critical applications. What should be noticed is that BIMMF also should be handled with appropriate care as all optical glass fibers.

Ruggedized Fiber Optic Cables for Harsh Environment

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As a perfect choice for today’s telecommunication which requires a larger bandwidth, fiber optic cables have been widely put into use and get more popularity. However, when optical cables are increasingly used in different applications with diverse environments, for example, from indoor to tough environments, new and demanding requirements also have been put forward for them. Before deployment, several considerations may occur. For instance, can they resist the erosion of oil or chemicals? Can they still work normally in changeable weather? Do they have rodent-resistant ability? The answer of all the questions is yes. Today’s fiber optic cables possess various abilities to meet different requirements. Here is a brief introduction several ruggedized fiber optic cables that can work in different harsh environments, providing more conveniences and extra protection for network systems.
Armored Fiber Optic Cable
Armored fiber optic cable is one of the most commonly used cables to offer protection for fibers. Generally, armored fiber optic cable contains a helical stainless steel tap over a buffered fiber surrounded by a layer of aramid and stainless steel mesh with an outer jacket. With this unique construction, it can withstand the toughest environments—high temperatures, high pressures, and harsh vibrations as well as animals rodent and moisture. In a word, with the protection of flexible and durable steel tube, armored fiber patch cable will ensure the excellent operation of networks.
IP67 Waterproof Fiber Optic Cable
IP67 waterproof fiber optic cable is another kind of ruggedized cables used for outdoor applications. They are with strong PU jacket and stainless steel armor inside for future protection. “IP” in this term is a type of protection rating defined by International Standard IEC 60529. The number “6” and “7” mean this kind of cable possesses a good ability to resist dust and water. According to the connector types, the IP67 waterproof fiber optic cables have several types including IP67 MTP/MPO fiber cables, IP67 LC waterproof fiber cable and so on. IP67 waterproof fiber optic cables will not get damage even stepped, and are anti-rodents and suitable for use in harsh environment like communication towers and CATV (Community Antenna Television), providing protection for your networks. Here is a picture of IP67 LC component details.
Military Grade Fiber Optic Cable
Military grade fiber optic cable is the last type of ruggedized fiber cable to be introduced. They are manufactured with specialized military tactical fiber cable that has excellent impact and crush resistance characteristics, which comply with military requirements. Generally, they have an outdoor-rated polyurethane jacket that resists UV radiation, cuts, abrasions and chemicals, which is an ideal choice for military vehicles and field deployed communications equipment.
There is a multitude of challenges in military communications. Designed for uncompromising dependability in the harshest conditions, these military grade fiber optic cables are a cost-effective network alternative and can provide essential communications solutions for military applications, including greater bandwidth for real-time voice, data and video applications and easily deployable platform.
Summary
With the rapid development of optical communication around the world, more and more fiber optic cables are increasingly used in different environments. Under harsh conditions, the ruggedness and durability of common fiber optic cables cannot meet operators’ requirements, especially for exceptional demanding applications. This post mainly introduces three types of ruggedized fiber optic cable. All the cables mentioned above are available in fiber-mart.COM. If you have any problems about them, please contact us via sales@fiber-mart.com.

The Application of 10G PON Technology

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With the major carriers “Broadband speed”, “Light of Copper” project extensively, The future will be a multimedia broadband services, video on demand, interactive games as the main feature, high-bandwidth, integrated operators will be judged promoted by the merits of the standard broadband products.
Under the broadband Fiber Optic Products in the trend, PON technology has become the world’s attention to various telecom operators hot technology is one of the operators to implement “broadband speed”, “Light of Copper” engineering technology base. Wheter EPON, or GPON, which provides only for the uplink and downlink bandwidth of 1G or 2G, but with the current interactive network TV (IPTV), high definition television (HDTV), online games, video services and other large flow, a large broadband business development and popularization of the per-user bandwidth demand is expected to grow every three years, a trend of increasing magnitude, from the future operator of long-term trends, per-user bandwidth demand will be 50-100 Mbit/s between. This way, EPON and GPON are unable to meet the future needs of the development of broadband services, the existing PON port bandwidth, there will be a bottleneck. Therefore, ITU-T, FSAN, IEEE and other major standards organizations begin the next generation of PON technology research.
Similar to 1G PON Technology, 10G PON and 10G EPON technology is still divided into two camps 10G GPON. In IEEE 802.3av 10G EPON standards, maximizing follows the usual IEEE 802.3ah content, with good upward compatibility.
10G PON technical analysis
Recalling the history of PON technology can be found in each of the PON technology from birth to the end of the day have to go through large-scale commercial development of technical standards, the relevant chip and optical module development, test and production, the creation of experimental and commercial bureau 4 stages of deployment, which lasted five years or so, each one of which will go through several stages of development of the argument.
Standardization Advances
Standards are mature is the precondition of judging whether a technology have lead to condition. At this stage, including IEEE, ITU-T, FSAN and number of ongoing international standardization organizations 10G EPON and 10G GPON standards development work of two technologies. Overall, the 10G EPON technology start time earlier than 10G GPON, therefore, the current standardization process of 10G EPON slightly faster than 10G GPON.
a. 10G EPON
Technologies with 1G EPON, 10G EPON standards are mainly led by the IEEE to complete. IEEE organization at September 12, 2009 released the 10G EPON international standards 802.3av, this standard focuses on the physical layer 10G EPON technology research, followed the tradition of 1G EPON MPCP protocol, the 1G EPON downlink bandwidth increases to 10G at the same time, to ensure that the operator of the original investment is not compromised and 10G EPON smooth upgrade, IEEE 802.3av standard defines and 1G EPON ONU coexist in the same ODN network of 10G EPON ONU standard parameters.
Further, in IEEE 802.3av standard, the physical layer defines two parameters: one asymmetric model, which 10G rate downlink and 1G rate uplink; other is symmetrical pattern, i.e. uplink rate and downlink rate are both 10G. Asymmetric mode can be considered as a transitional form symmetrical patterns, in the early less demand for upstream bandwidth and cost sensitive applications, you can use an asymmetric form. With the development of business and technology progress, will be gradually transition to a symmetrical mode.
b. 10G GPON
According to ITU-T Study plans, NGPON will experience two standard phases: the first phase is the coexistence with GPON, GPON ODN heavy use of XG-PON, which in turn contains the uplink and downlink phase XG-PON1 asymmetric and symmetric XG-PON2 two kind of model; Second stage is completely new ODN’s NGA2. High concern Wavelength Division Multiplexing – Passive Optical Network (WDM-PON) technology areas belong to the second stage, it was adopted in a fiber access network using multiple wavelengths to achieve the expansion, but the burst mode CWDM, colorless ONU transceivers, tunable WDM devices and some difficult technology can not break, WDM-PON is still at the proof stage.
In the end of September 2009 meeting of the ITU-T SG 15 plenary session, Q2 Working Group officially launched the NG-PON standard text in the first stage, that overall demand for next-generation PON systems (G.987.1) and Physical Layer Specifications (G.987.2), and also developed in mid-2010, publishing transmission convergence layer (G.987.3) and management control interface (G.988) standards program.
Technical Parameters
Wheter IEEE 802.3av, or ITU-T G.987 protocol suite, all relevant technical parameters for 10G PON physical layer index, optical power budget to make a detailed definition. However, due to the two major standards organizations considered the starting point, the technical indicators are also some differences.
a. 10G EPON
There are four key points of 10G EPON technology:
1. Defines six 10G EPON optical power budget, in view of the asymmetric mode PRX10, PRX20 and PRX30 as well as for symmetric mode PR10, PR20 and PR30, these six kinds of optical power budget model is basically to meet the construction needs of the service provider network;
2. 10G EPON technology in achieving the 1G EPON conventional multi-point control protocol layer (MPCP) based on the forward compatibility, also extended the original message type, for reporting optical terminal equipment (OLT), ONU Fiber Optic Transceiver switch time to meet the 10G EPON system requirements;
3. 10G EPON uses (255, 223) Forward Error Correction (FEC) encoding method, the encoded with FEC coding for the same strain of 1G EPON, but its strong support 10G EPON coding gain can lower the sensitivity of the optical receiver;
4. 10G EPON uplink and downlink wavelength for the re-planning, downlink using 1268-1280nm wavelength, then reuse the original uplink of 1G EPON 1575-1580 nm wavelength, the wavelength in order to avoid conflicts, 10G EPON uplink only use time division multiple access (TDMA) manner.
b. 10G GPON
Has been released G.987.1 standard that defines 10G GPON system’s overall technical requirements and system architecture, clearly put forward the 10G GPON system to ensure good QoS, based on the traditional telecom services to fully support all emerging businesses and the same time, also provides dynamic Bandwidth Allocation (DBA) algorithm, energy saving, authentication and encryption related content to inherit the original 1G GPON technology; The G.987.2 is the focus of standardized 10G GPON physical layer parameters, including downlink rate, ODN power budget, splitting ratio, up and down the line wavelength range and line coding, etc., although down the line of 10G EPON same wavelength range and 10G EPON, GPON but due to the wavelength with 1G is not conflict, therefore, 10G GPON uplink and downlink are used wavelength division multiple access (WDMA) manner.
Industrial chain development
A complete industrial chain, including chip PON, optical modules and equipment three links. If to analysis PON industry chain, it need to start from the three links, analysis of every link current development status and future development trend.
Overall, 10G EPON and 10G GPON is currently not reach the requirements of large-scale commercial applications, although some equipment manufacturers have recently introduced a 10G EPON or 10G GPON products, and with operators, the creation of some experimental inning, but still in the laboratory testing phase, is still some distance away from the large-scale commercial.
Conclusion
10G PON technology to meet future access networks, “large-capacity, fewer offices,” the direction of development, while improving access speed, supports larger branching ratio, covering more users. Therefore, 10G PON technology will become the future telecom operators to achieve “broadband speed”, “Light of Copper” and other broadband network construction hot technology for sustainable development.

Introduction of the Transients in Optical WDM Networks

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A systems analysis continues to be completed to consider dynamical transient effects in the physical layer of an Optical WDM Network. The physical layer dynamics include effects on different time scales. Dynamics from the transmission signal impulses possess a scale of picoseconds. The timing recovery loops in the receivers be employed in the nanoseconds time scale. Optical packet switching in the future networks will have microsecond time scale. Growth and development of such optical networks is yet continuing. Most of the advanced development work in optical WDM networks is presently focused on circuit switching networks, where lightpath change events (for example wavelength add/drop or cross-connect configuration changes) happen on the time scale of seconds.
It is focused on the dynamics from the average transmission power associated with the gain dynamics in Optical Line Amplifiers (OLA). These dynamics may be triggered by the circuit switching events and have millisecond time scale primarily defined by the Amplified Spontaneous Emission (ASE) kinetics in Erbium-Doped Fiber Amplifiers (EDFAs). The transmission power dynamics will also be influenced by other active components of optical network, for example automatically tunable Optical Attenuators, spectral power equalizers, or other light processing components. When it comes to these dynamics, a typical power of the lightpath transmission signal is recognized as. High bandwidth modulation from the signal, which actually consists of separate information carrying pulses, is mostly ignored.
Ring WDM networks implementing communication between two fixed points are very well established technology, in particular, for carrying SONET over the WDM. Such simple networks with fixed WDM lighpaths happen to be analyzed in many detail. Fairly detailed first principle models for transmission power dynamics exist for such networks. These models are implemented in industrial software allowing engineering design calculations and dynamical simulation of these networks. Such models could possibly have very high fidelity, but their setup, tuning (model parameter identification) and exhaustive simulations covering a variety of transmission regimes are potentially very labor intensive. Adding description of new network components to such model could need a major effort.
The problems with detailed first principle models is going to be greatly exacerbated for future Mesh WDM networks. The near future core optical networks will be transparent to wavelength signals on a physical layer. In such network, each wavelength signal travels through the optical core between electronic IP routers around the optical network edge using the information contents unchanged. The signal power is attenuated in the passive network elements and boosted by the optical amplifiers. The lightpaths is going to be dynamically provisioned by Optical Cross-Connects (OXCs), routers, or switches independently on the underlying protocol for data transmission. Such network is basically a circuit switched network. It might experience complex transient processes of the average transmission power for every wavelength signal at the event of the lightpath add, drop, or re-routing. A mix of the signal propagation delay and channel cross-coupling might result in the transmission power disturbances propagating across the network in closed loops and causing stamina oscillations. Such oscillations were observed experimentally. Additionally, the transmission power and amplifier gain transients could be excited by changes in the average signal power because of the network traffic burstliness. If for some period of time the wavelength channel bandwidth is not fully utilized, this could result in a loss of the average power (average temporal density of the transmitted information pulses).
First circuit switched optical networks are already being designed and deployed. Fraxel treatments develops rapidly for metro area and long term networks. Engineering design of circuit switched networks is complicated because performance has to be guaranteed for all possible combinations of the lightpaths. Further, as such networks develop and grow, they potentially need to combine heterogenous equipment from a variety of vendors. A system integrator (e.g., fiber-mart.com) of such network might be different from subsystems or component manufacturer. This creates a necessity of developing adequate means of transmission power dynamics calculations which are suitable for the circuit switched network business. Ideally, these methods should be modular, independent on the network complexity, and use specifications on the component/subsystem level.
fiber-mart.com has technical approach to systems analysis that’s to linearize the nonlinear system around a fixed regime, describe the nonlinearity like a model uncertainty, and apply robust analysis that guarantees stability and gratifaction conditions within the presence of the uncertainty. For a user of the approach, there is no need to understand the derivation and system analysis technicalities. The obtained results are very simple and relate performance to basic specifications of the network components. These specifications are somewhat not the same as those widely used in the industry, but could be defined from simple experimentation using the components and subsystems. The obtained specification requirements may be used in growth and development of optical amplifiers, equalizers, optical attenuators, other transmission signal conditioning devices, OADMs, OXCs, and any other optical network devices and subsystems influencing the transmission power.

A Guidance to Fiber Optic Cable Selection

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With the advances of the information age, a great amount of people specialized in the field of network communication begins to attach great importance to the selection of fiber optic cables. From data and voice to security and videoconferencing, plenty of contemporary cable infrastructure services depend heavily on fiber optics to transmit information of farther distance at a higher speed, which makes fiber optics a standard component in daily communication nowadays. Fiber optics are considered to be a desirable cable medium because of its immunity to electromagnetic interference (EMI) and radio frequency interference (RFI) , not to mention its bandwidth that helps to meet the increased capacity demand, and its reliable reputation to ensure worry-free maintenance. This article is going to focus primarily on some essential component in fiber optic installation and provide some insight into selecting the right fiber optic cable.
The Necessities of Selecting the Right Type of Fiber
Fiber optic cable basically can be used in a wide variety of applications, ranging from small office LANs, data centers to inter-continental communication links. Moreover, its ability to transport signals for significant distances also contributes to its popularity in most networks, whether they are local, wide area or metropolitan. In fact, fiber optic cable is now running down many residential streets and brought directly to the house. Thus, choosing the appropriate fiber optic cable is extremely important for any installation.
It is known to all that the selection concerning the right type of fiber should be based on the immediate application since it varies in different circumstances. Besides, installers should also consider upcoming applications and capacity needs. Future bandwidth demands, transmission distances, applications, and network architecture influence fiber selection just as much as current needs. Therefore, a careful assessment of potential network usage will help avoid the costs of preventable upgrades.
Single-mode Fiber Optic Cable vs. Multimode Fiber Optic Cable
First and foremost, on selecting the right type of fiber, one should decide the mode of fiber needed. The mode of a fiber cable describes how light beams travel on the inside of the fiber cables themselves. Since the two modes aren’t compatible with each other and you can’t substitute one for the other, it is important to make the right choice.
Single-mode fiber optic cable uses a single strand of glass fiber for a single ray of light transmission, which can accommodate further distances and offer virtually unlimited bandwidth. Single-mode has the capacity to carry a signal for miles, making it an ideal option for telephone and cable television providers. And it is also usually employed in campus and metropolitan networks. Single-mode fiber requires laser technology for sending and receiving data, and the high-powered lasers transmit data at greater distances than the light used with multimode fiber.
Multimode fiber optic fiber, as the name indicates, allows the signal to travel in multiple modes, or pathways, along the inside of the glass strand or core. Multimode fiber optic cable is generally adopted in applications involving shorter distances like data center connections. Multimode fiber optic cable transmits Gigabit Ethernet up to 550 m, although it can’t compete with single-mode fiber optic cable in terms of transmission distance, multimode fiber cable is still proved to be a cost-efficient and economical solution.
Making the Connection
Connections play an essential role in keeping the information flowing from cable to cable or cable to device. There are lots of connector styles on the market including LC, FC, MT-RJ, ST and SC. There are also MPO/MTP style connectors that will accommodate up to 12 strands of fiber and take up far less space than other connectors. Among them, manufacturers and distributors are more likely to have equipment to accommodate ST and SC style connectors than any other connector style. Especially the SC connectors, with better performance against loss, more efficient installation and easier maintenance, has earned its place in today’s networking applications. As for those data center managers who attach more importance to space-saving, the LC connector is a more ideal option. These connectors offer even lower loss in a smaller form factor and provide higher performance and greater fiber density.
Evaluating Interface Options
In addition to fiber type and connector selection, another vital issue for the technician is to evaluate the interface option which determines the network performance. The selection of interface is relevant to the fiber type, cable distance and speed of the connection as well. Installers can rely on modular Gigabit fiber-optic interfaces, called gigabit interface converters (GBICs) for most interface converters. These flexible interfaces come in several form factors, including XENPAK and SFP+, and can accommodate a variety of device applications. The picture below shows a typical gigabit fiber optic converter.
While choosing the right interfaces, installers need to take their light sources into consideration. Light-emitting diodes (LEDs) work only with multimode fiber and operate at the 850nm window; laser works only with single-mode fiber and operates at the 1550nm window; and vertical-cavity surface-emitting laser (VCSEL) works with both types of fiber and operates at the 1310nm window.