A WDM (Wavelength Division Multiplexing) is a system that uses a multiplexing (at the transmitter) and a demultiplexer (at the receiver) for the completion of the process and transmission of the signals.
The WDM is divided into three types (WDM, CWDM and DWDM) on the basis of wavelength difference among the three. The article discusses the main differences among CWDM and DWDM.
CWDM stands for Coarse Wavelength Division Multiplexing, and DWDM is the acronym for Dense Wavelength Division Multiplexing. Whether DWDM or CWDM, both are the types of WDM mechanism and have an array of differencess.
Let’s get acquainted with the chief difference between CWDM and DWDM:
The Coarse WDM has less than 8 active wavelengths per optical fiber whereas the DWDM has more than 8 active wavelengths per optical fiber.
The CWDM has lower capacity strength and hence is low in costs; conversely the DWDM possesses high capacity –this leads to an augmented price which is worth its qualities.
When it comes to the difference between the distance of the two, the CWDM has short range communication because the wavelength is not amplified, and DWDM has long range communication.
CWDM Mux and Demux systems are developed to be used in multiplexing multiple CWDM channels into one or two fibers.
Another major difference is that DWDM systems are made for longer haul transmittal, by keeping the wavelengths closely packed. Also, a DWDM device can transmit more data over long distances and to a significantly larger run of cable with lesser interference than a comparable CWDM system which has a shorter haul transmittal.
Furthermore, the Dense Wavelength Division Multiplying systems are capable to fit more than forty different data streams in the amount akin to that of fiber used for two data streams in a CWDM system.
Apart from all the difference there is one more and that is wavelength drift is possible in CWDM, but when it comes to the DWDM –precision lasers are needed to keep channels on the target.
Beyond being different from each other –these systems play different roles in the effective transfer of the signals, and thereby both are important enough.
CWDM multiplexer and DWDM multiplexer are two main products of WDM multiplexer. The full name of WDM, CWDM and DWDM are wavelength division multiplexing, coarse wavelength division multiplexing and dense wavelength multiplexing respectively. How much do you know about them? If you have no idea, the following introduction will help you a lot.
In the very first place, let’s get to know what the WDM is. Based on a single fiber optic transmission, many optical signals that are loaded with information and have different wavelengths can be synthesized into one single beam by WDM multiplexer. Then, a special communication technology will be adopted to separate those optical signals at the receiving terminal. On the basis of WDM technique, the CWDM device and DWDM device are two popular products in the current market.
CWDMdevice
When it comes to the CWDM multiplexer, first of all, it provides service for metropolitan area network access layer, whose working principle is in line with WDM multiplexer. However, it simplifies the structure largely. For example, the filter film layer number of CWDM is just 50, while the WDM is as many as 200 layers. That is to say, the rate of finished products has been improved and the cost has been reduced largely. Besides low cost, the CWDM device is also advantageous in small volume, small power consumption, convenient maintenance and large transmission capacity. The laser device in the system doesn’t need semiconductor refrigerator and temperature controller, which can lessen the power consumption obviously. However, the CWDM also has shortcomings. For instance, developing and simplifying the optical transceiver module and optical component is urgent to be solved.
DWDM device
As to the DWDM multiplexer, comparatively speaking, it makes the best use of fiber-optical bandwidth and enhances the message capacity of cellular system, which is well-known for simple dilatation and stable performance. Integrated system and open system are two dominant application systems of DWDM multiplexer, which are based on different wavelength conversion technologies. No matter which system is adopted, the free-running 1510nm wavelength will be chosen to carry OSC or optical supervisory channel so as to transmit information. Such an OSC is a comparatively independent subsystem, which offers maintenance and management information.
The last question is what advantages WDM technique has when compared with traditional transmission methods. Generally speaking, it includes such aspects as making best use of low-loss wave band, transmitting several optical signals in one optical fiber, good flexibility, low investment cost, excellent system reliability and fast and convenient recovery.
Do you know these about CWDM Multiplexer and DWDM Multiplexer?
Wavelength division multiplexing (WDM) is a technology or technique modulating numerous data streams, i.e. optical carrier signals of varying wavelengths (colors) of laser light, onto a single optical fiber. The goal of WDM is to have a signal not to interfere with each other. It is usually used to make data transmission more efficiently. It has also been proven more cost effective in many applications, such as WDM network applications, broadband network application and fiber to the home (FTTH) applications and so on. According to channel spacing between neighbored wavelengths, there are two main types of WDM, including Coarse WDM (CWDM) and Dense WDM (DWDM). Though both of them belong to WDM technology, they are quite different. Then, what are the differences between them? This paper will give you the answer.
Definition of CWDM
CWDM is a method of combining multiple signals on laser beams at various wavelengths for transmission along fiber optic cables, such that the number of channels is fewer than in DWDM but more than in standard WDM. “Course” means the channel spacing is 20nm with a working channel passband of +/-6.5nm from the wavelengths center. From 1270nm to 1610nm, there are 18 individual wavelengths separated by 20nm spacing.
Definition of DWDM
DWDM is a technology that puts data from different sources together on an optical fiber, with each signal carried at the same time on its own separate light wavelength. “Dense” refers to the very narrow channel spacing measured in Gigahertz (GHz) as opposed to nanometer (nm). DWDM typically uses channel spacing of 100GHz with a working channel passband of +/-12.5GHz from the wavelengths center. It uses 200GHz spacing essentially skipping every other channel in the DWDM grid. And it has also gone one step further using an Optical Interleaver to get down to 50GHz spacing doubling the channels’ capacity from 100GHz spacing.
CWDM vs DWDM
According to the content above, you will find some small differences between them. 16CH CWDM Module is defined by wavelengths and has wide range channel spacing. DWDM is defined by frequencies and has narrow channel spacing. What’s more, what other differences do they have?
Capacity of Data
In fiber optic network system, DWDM system could fit more than 40 different data streams in the same amount of fiber used for two data streams in a CWDM system. In some cases, CWDM system can perform many of the same tasks compared to DWDM. Despite the lower transmission of data through a CWDM system, these are still viable options for fiber optic data transmission.
Cost of Cable
CWDM system carries less data, but the cabling used to run them is less expensive and less complex. A DWDM system has much denser cabling and can carry a significantly larger amount of data, but it can be cost prohibitive, especially where there is necessary to have a large amount of cabling in an application.
Long-haul or Short-haul Transmission
DWDM system is used for a longer haul transmission through keeping the wavelengths tightly packed. It can transmit more data over a significantly larger run of cable with less interference. However, CWDM system cannot travel long distances because the wavelengths are not amplified, and therefore CWDM is limited in its functionality over longer distances. If we neeed to transmit the data over a very long range, DWDM system solution may be the best choice in terms of functionality of the data transmission as well as the lessened interference over the longer distances that the wavelengths must travel. As far as cost is concerned, when required to provide signal amplification about 100 miles (160km), CWDM system is the best solution for short runs.
According to the content above, maybe you have already understood some differences between CWDM and DWDM by the comparision of them from definition, capacity, cable cost and transmission distance etc. And here is also a figure of comparisons between CWDM and DWDM which may help you to consolidate your understanding of this paper.
Using a WDM(Wavelength Division Multiplexing) for expanding the capacity of the fiber to carry multiple client interfaces is a highly advisable way as the physical fiber optic cabling is not cheap. As WDM widely used you must not unfamiliar with it, it is a technology that combines several streams of data/storage/video or voice protocols on the same physical fiber-optic cable, by using several wavelengths (frequencies) of light with each frequency carrying a different type of data.
Two types of WDM architecture available: Coarse Wavelength Division Multiplexing (CWDM) and Dense Wavelength Division Multiplexing (DWDM). CWDM/DWDM multiplexer and demultiplexer and OADM (Optical Add-Drop Multiplexer) are common fit in with Passive. With the use of optical amplifiers and the development of the OTN (Optical Transport Network) layer equipped with FEC (Forward Error Correction), the distance of the fiber optical communication can reach thousands of Kilometers without the need for regeneration sites.
CWDM
Each CWDM wavelength typically supports up to 2.5Gbps and can be expanded to 10Gbps support. The CWDM is limited to 16 wavelengths and is typically deployed at networks up to 80Km since optical amplifiers cannot be used due to the large spacing between channels. CWDM uses a wide spectrum and accommodates eight channels. This wide spacing of channels allows for the use of moderately priced optics, but limits capacity. CWDM is typically used for lower-cost, lower-capacity, shorter-distance applications where cost is the paramount decision criteria.
The CWDM Mux/Demux (or CWDM multiplexer/demultiplexer) is often a flexible plug-and-play network solution, which helps insurers and enterprise companies to affordably implement denote point or ring based WDM optical networks. CWDM Mux/demux is perfectly created for transport PDH, SDH / SONET, ETHERNET services over WDM, CWDM and DWDM in optical metro edge and access networks. CWDM Multiplexer Modules can be found in 4, 8 and 16 channel configurations. These modules passively multiplex the optical signal outputs from 4 too much electronic products, send on them someone optical fiber and after that de-multiplex the signals into separate, distinct signals for input into gadgets across the opposite end for your fiber optic link.
Typically CWDM solutions provide 8 wavelengths capability enabling the transport of 8 client interfaces over the same fiber. However, the relatively large separation between the CWDM wavelengths allows expansion of the CWDM network with an additional 44 wavelengths with 100GHz spacing utilizing DWDM technology, thus expanding the existing infrastructure capability and utilizing the same equipment as part of the integrated solution.
DWDM
DWDM is a technology allowing high throughput capacity over longer distances commonly ranging between 44-88 channels/wavelengths and transferring data rates from 100Mbps up to 100Gbps per wavelength.
DWDM systems pack 16 or more channels into a narrow spectrum window very near the 1550nm local attenuation minimum. Decreasing channel spacing requires the use of more precise and costly optics, but allows for significantly more scalability. Typical DWDM systems provide 1-44 channels of capacity, with some new systems, offering up to 80-160 channels. DWDM is typically used where high capacity is needed over a limited fiber resource or where it is cost prohibitive to deploy more fiber.
The DWDM multiplexer/demultiplexer Modules are made to multiplex multiple DWDM channels into one or two fibers. Based on type CWDM Mux/Demux unit, with optional expansion, can transmit and receive as much as 4, 8, 16 or 32 connections of various standards, data rates or protocols over one single fiber optic link without disturbing one another.
Ultimately, the choice to use CWDM or DWDM is a difficult decision, first we should understand the difference between them clearly.
CWDM vs DWDM
CWDM scales to 18 distinct channels. While, DWDM scales up to 80 channels (or more), allows vastly more expansion. The main advantage of CWDM is the cost of the optics which is typically 1/3rd of the cost of the equivalent DWDM optic. CWDM products are popular in less precision optics and lower cost, less power consumption, un-cooled lasers with lower maintenance requirements. This difference in economic scale, the limited budget that many customers face, and typical initial requirements not to exceed 8 wavelengths, means that CWDM is a more popular entry point for many customers.
Buying CWDM or DWDM is driven by the number of wavelengths needed and the future growth projections. If you only need a handful of waves and use 1Gbps optics, CWDM is the way to go. If you need dozens of waves, 10Gbps speeds, DWDM is the only option.
The key components in a WDM system are the optical wavelength multiplexer (MUX), and the de-multiplexer (DEMUX). In general, a CWDM (coarse WDM) MUX/DEMUX deals with small numbers of wavelengths, typically eight, but with large spans between wavelengths (spaced typically at around 20nm). A DWDM (dense WDM) MUX/DEMUX deals with narrower wavelength spans (as small as 0.8nm, 0.4nm or even 0.2nm), and can accommodate 40, 80, or even 160 wavelengths.
The one kind of DK Photonics LGX CWDM MUX/DEMUX modules are bi-directional passive optical multiplexers and de-multiplexers, allowing multiple optical signals at different wavelengths to pass through a single optical fiber strand.
The second DK Photonics ABS CWDM MUX/DEMUX modules are duplex fiber link bi-directional multiplexers and de-multiplexers, allowing multiple optical signals’ at different wavelengths to pass through duplex optical fiber.
The last one kind is simplex directional CWDM MUX only or CWDM DEMUX only. The kind of mux and demux must be used with each other.
CWDM MUX/DEMUX solution lets operators make full use of available fiber bandwidth in local loop and enterprise architectures. Our CWDM MUX/DEMUX modules split up to 18 channels (20 nm spaced) to a single fiber. The standard packages are ABS Plastic Box, 19″ Rack Mount Chassis CWDM Mux/Demux and LGX Metal Box Mux/Demux. No matter what kinds of connectors (such as FC, ST, SC, LC, etc.) are all available and we can also mix connectors on one device.
CWDM MUX+DEMUX 8 Channels (Dual Fiber) Module
DK Photonics offers a wide range of WDM (Wavelength Division Multiplexing) optical networking products that allow transport of any mix of services from 2Mbps up to 100Gbe over dark fiber and WDM networks providing for the entire set of the most demanding CWDM and DWDM network infrastructure needs.
The market value of fiber optic circulators increased 10.77% in 2014…
Aptos, CA (USA) – March 9, 2015 —ElectroniCast Consultants, a leading market research & technology forecast consultancy addressing the fiber optics communications industry, today announced the release of a new market forecast of the global consumption of fiber optic circulators in optical communications.
During 2014-2019, the consumption value is forecast to increase with rising quantity growth partially offset by declining average prices.
The fiber optic circulator market is presented by the following port-count configurations: 3-Ports; 4-Ports; and more than 4-Ports (> 4 – Ports). According to ElectroniCast, the worldwide use of fiber optic circulators reached $244.8 million in 2014, an increase of 10.77% over he total consumption value of $227.4 million in 2013. 3-Port fiber optic circulators held an 80% market share in 2014. Well-over 70% of the 3-Port fiber optic circulator market value in 2014 was in Telecommunication applications.
Telecommunications is set to maintain its dominant market share lead throughout the forecast period. Specialty applications (R&D laboratory, sensors, test equipment, oil/gas, other) are set to maintain the position of second-place, according to the ElectroniCast market forecast and analysis study.
Fiber Optic Circulators are non-reciprocal devices, which means that changes in the properties of light passing through the device are not reversed when the light passes through in the opposite direction. The optical device is commonly used in a wide variety of systems, here are just a few examples: dispersion compensation, optical sensors, optical amplifiers, WDM systems, optical add/drops multiplexing (OADMs) and test/measurement instruments such as optical time-domain reflectometers (OTDRs), remote fiber (optic) test systems (RFTS) and other test equipment.
The deployment of optical fiber in the metro/access, the continuing demand for upgrading networks to accommodate rapidly increasing bandwidth requirements, plus the need for additional monitoring and testing of the optical fiber networks will drive the steady consumption of fiber optic circulators.
According to ElectroniCast Consultants, 3-Port fiber optic circulators held an 80% (value) market share in 2014…
Fiber Optic Circulator Global Market Share (%), By Port Count
(2014 – ElectroniCast Estimate: $244.8 Million)
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According to ElectroniCast, optical isolator value in Telecommunications is forecast to increase 19.6% this year…
Aptos, California (USA) – April 29, 2014 —ElectroniCast Consultants, a leading market research & technology forecast consultancy addressing the fiber optics communications industry, today announced the release of a new market forecastof the global consumption of optical isolators in optical communication and specialty applications.
According to ElectroniCast, the worldwide optical isolator consumption was led by Telecommunication applications in 2013 with a 70 percent market share or $349.7 million, and is forecasted to increase 19.6 percent in value to $418.2 million this year (2014). Market forecast data in this study report refers to consumption (use) for a particular calendar year; therefore, this data is not cumulative data.
Optical isolators are devices that allow light to be transmitted in only one direction. They are most often used to prevent any light from reflecting back down the optical fiber, as this light would enter the source and cause backscattering and feedback problems. This is especially important for high data rate transceivers and transponders, or those devices requiring long span lengths between transceiver pairs. Optical feedback degrades signal-to-noise ratio and consequently bit-error rate.
“Continuing demand for upgrading communication networks to accommodate rapidly increasing bandwidth requirements will drive the steady consumption of optical fiber links. Optical isolators are used in with high-speed transmitters that are required to transmit longer distances and/or multiple wavelength transmitters,” stated Stephen Montgomery, Director of the Fiber Optics Components group at ElectroniCast Consultants.
Optical isolators are not widely used in Private Enterprise applications; however, worldwide use of fiber optic isolators in Cable TV controlled device deployments are forecast to grow significantly in value at an annual rate of 8.8 percent (2013-2018), as optical fiber is deployed closer to the home driven by multi-media applications.
Optical isolator units are used in a variety of Military/Aerospace applications requiring rigorous testing and harsh environment fiber optic (HEFO) certification to ensure reliability and performance. Laser-based fiber optic technology incorporating optical isolators are used in a wide variety of air, sea, ground, and space applications.
A major user-group within the Specialty application category is Laboratory/R&D. Optical isolators are used for noise reduction, medical imaging, pulse selection for mode locked lasers, sensing, regeneration switches, disc master, optical trapping, phase shifters, frequency modulation spectroscopy and general shuttering. The optical isolators are also used in sensing for industrial, structures and other many other communication product-oriented manufacturing/test/R&D uses.
“During the forecast period (2013-2018), bandwidth expansion demands will push for new network links, incorporating Metro Core, Metro/Access, Long Haul, Optical Fiber Amplifiers, WDM, OADM and other system-based deployments, which incorporate optical isolators,” Montgomery added.
The American region held the lead in terms of relative market share consumption value of optical isolators in 2013, with nearly 43.4 percent; however the American region is forecast to increase at a slower rate compared to the other regions (2013-2018). The Asia Pacific region (APAC) is forecast to increase in worldwide market share from 39.7 percent in 2013 to with 53.7 percent in 2018. The Europe, Middle East, African region (EMEA) is forecast to remain in the third-place position, however, increase at a faster annual pace versus the American region.
According to ElectroniCast, the American Region leads optical isolator consumption value…
2013 – Optical Isolator Global Value Market Share (%),
By Region, $498 Million
Source: ElectroniCast Consultants
Optical Isolator Global Value Market Share (%)
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A fiber-optic multiplexer is a device that processes two or more light signals through a single optical fiber, in order to increase the amount of information that can be carried through a network. Light wavelengths are narrow beams that ricochet through reflective optical tubing, sometimes over long distances, to provide instantaneous electronic signal processing at the speed of light. Multiplexers work by increasing a fiber’s transmission capacity using different techniques and light source technologies. When the signal arrives at its destination, a demultiplexer separates the data streams. Using a multiplexer also allows data to be sent farther, more securely, and with less electromagnetic and radio frequency interference.
16CH CWDM
Also known as a mux, the fiber-optic multiplexer saves time and cost by squeezing more information through the optical network pathway. It is possible to split signals by varying the schedule or period of each transmission. Time Division Multiplexing (TDM) combines multiple signals by rapidly alternating between them so that only one is transmitting at any given time. Statistical Time Division Multiplexing (STDM) assigns each signal a specific time slot in order to optimize bandwidth usage. Further techniques include divisions of wavelength and frequency.
Wavelength Division Multiplexing (WDM) utilizes the total available pass band of an optical fiber. It assigns individual information streams different wavelengths, or portions of the electromagnetic spectrum. Similarly, Frequency Division Multiplexing (FDM) assigns each signal a different frequency. Carrier frequencies contain the signal while unused guard frequencies provide buffering to reduce interference. This helps minimize audible and visual noise and preserves the integrity of the original signal throughout the network.
Fiber-optic multiplexer technology serves single-mode and multimode optical fibers with multichannel rack mount or standalone units. This makes mixing channels with different configurations possible for a range of interface combinations. These devices provide stronger, more reliable transmissions in areas that have a lot of electromagnetic, radio frequency, or lightning interference.
As technology improves and information needs grow to fill the capacities of existing networks, equipment such as the fiber-optic multiplexer lessens the need to upgrade the fiber-optic infrastructure itself. Multiplexers permit new configurations of transmission protocols by increasing the amount of wavelengths or frequencies of light signals. By upgrading repeaters and terminal equipment, existing network transmission capacity can expand with demand.
Used by cellular carriers, Internet service providers, public utilities, and businesses, fiber-optic multiplexer technology extends the reach and power of telecommunications technologies. Network management systems allow for system service and maintenance, and provide for security, fault management, and system configuration. With advantages like lower costs and longer life expectancies, current fiber-optical networks are aided by improvements in multiplexing technology, and may provide light speed data transmission well into the future.
DK Photonics – www.dkphotonics.com specializes in designing and manufacturing of high quality optical passive components mainly for telecommunication, fiber sensor and fiber laser applications,such as PLC Splitter, WDM, FWDM, CWDM, DWDM, OADM,Optical Circulator, Isolator, PM Circulator, PM Isolator, Fused Coupler, Fused WDM, Collimator, Optical Switch and Polarization Maintaining Components, Pump Combiner, High power isolator, Patch Cord and all kinds of connectors.
Many industry analysts believe that the increasing requirements for bandwidth scalability, quality of service, and support of the emerging traffic patterns required by video and broadcast standards will make copper networks insufficient for many high-bandwidth services in the future. Fiber availability is not universal, and the economics of new fiber deployments are often challenging; nevertheless, fiber will undoubtedly push deeper into access networks to support business services, mobile backhaul/fronthaul, multitenant buildings/fiber to the cabinet, and in some cases fiber to the home (FTTH), too. Yet today‘s fiber-based approaches, including TDM-PON/PLC Splitterand active point-to-point Ethernet, probably won’t meet the likely requirements of the next generation of bandwidth-intensive traffic, either.
WDM-PON is a passive optical networking approach — currently being developed by several companies — that can be used to more adequately address these challenges over fiber-based networks. A WDM-PON design can be used to separate optical-network units (ONUs) into several virtual point-to-point connections over the same physical infrastructure, a feature that enables efficient use of fiber compared to point-to-point Ethernet and offers lower latency than TDM-based approaches. A notable advantage of this approach is the combination of high capacity per user, high security, and longer optical reach. WDM-PON therefore is highly suitable for applications such as mobile backhaul or business Ethernet service provision.
Thus WDM-PON is poised to become the disruptive next generation access architecture. It will enable high-speed access for businesses, mobile backhaul, and eventually FTTH. WDM-PON also will enable operators to build converged networks and consolidate existing access networks, including potentially eliminating central offices to reduce cost while boosting performance.
There are several types of WDM-PON systems under development. They all have in common the use of passive, temperature-hardened DWDM optical filters in the remote node and colorless ONUs.
Basic WDM-PON architecture
FIGURE 1. Basic WDM-PON architecture.
DK Photonics – www.dkphotonics.com specializes in designing and manufacturing of high quality optical passive components mainly for telecommunication, fiber sensor and fiber laser applications,such as High Power Isolator,1064nm Components,PM Components,Pump Combiner,Pump Laser Protector,which using for fiber laser applications.Also have Mini-size CWDM, Optical Circulator, PM Circulator,PM Isolator, Fused Coupler,Mini Size Fused WDM.More information,please contact us.
