Differences Between Pre-Amplifier, Booster Amplifier and In-line Amplifier

Transmission distance has always been a key factor during deployment of fiber optic network. DWDM technologies, which are considered as the most cost-effective ways to increase the network capacity over long transmission distance, have been widely applied in our telecommunication network. To further extend transmission distance of optical signals transmission from the DWDM fiber optic transceivers, optical amplifiers are usually used in the DWDM network. Different types of optical amplifiers have been invented to meet the signal amplifying requirements at different situations. This post will introduce the differences between the three most commonly used optical amplifier: pre-amplifier, booster amplifier and in-line amplifier.

Basics of Optical Amplifier

In the past, if you want to extend the transmission distance of DWDM network, optical regenerator station is required to be installed in the fiber link every 80km to 100km. The regenerator station will electronically regenerate the optical signals to overcome the power loss and ensure that the optical signal can be detected at the receiver end. However, this requires a lot of money and is not easy to upgrade the whole network.

With optical amplifier, things become much easier. The optical amplifier can enlarge the optical signals without the regeneration. In addition, the network upgrading is more cost-effective with optical amplifier. Each optical amplifier has an important factor which is operation gain measured in dB. The operation gain of the optical amplifier should be carefully calculated to ensure the network performance. Pre-amplifier, booster amplifier and in-line amplifier are used in different places in the fiber optic network. And they support different operation gain according to the whole network requirement.

Pre-Amplifier, Booster Amplifier and In-line Amplifier

Pre-Amplifier is usually installed at the receiver end of the DWDM network to amplify the optical signal to the required level to ensure that it can be detected by the receiver. The following picture shows a typical diagram for a duplex 10G DWDM network which can support 80km. A pre-amplifier is installed at each receiving end of this network. There will be great power loss after the optical signal goes through the 80km optical fiber. Then, pre-amplifier installed at the receiver end is necessary. Generally, a pre-amplifier should offer high gain to ensure that the optical signal is detectable.

Booster Amplifier is installed in the transmitting end of the fiber optic network, which can amplifier the amplify the optical signal launched into the fiber link. It is usually used in DWDM network where the multiplexer attenuates the signal channels. The following picture shows a 10G DWDM network using booster amplifier (BA) at the transmitting end and pre-amplifier (PA) at receiving end. Thus, this 10G DWDM network can support a transmission distance much longer than the above mentioned one. Please note, a DCM (Dispersion Compensation Module) is added in this network to further ensure the transmission quality. A booster amplifier usually provides low gain and high output power.

In-line Amplifier is easy to understand. The gain provided by the pre-amplifier and booster amplifier might not be enough due to the optical loss caused by long haul transmission. In-line amplifier is installed in the fiber optic link every 80–100km as shown in the following picture. It has moderate gain and has similar output power to those of booster amplifier.

Conclusion

Optical amplifier can help to amplifier the optical power during long haul transmission to ensure that the receiver can detect the optical signal without error. Three amplifiers are commonly used in DWDM network. Booster amplifier is used to amplifier optical power at the transmitting end and pre-amplifier is placed at the receiver end. If the transmission distance is longer than 150km or have great power loss during transmission, in-line amplifier is suggested to be installed every 80km to 100k in the fiber optic link. The gain of these amplifiers should be carefully calculated during practical use. Kindly visit DWDM EDFA Amplifier page for more details.

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

CWDM modules'​ applications

Recently, some of our customers want to know more about the CWDM modules’ applications. Here we share some of CWDM knowledge to you, hope these can be helpful for your business!

1. What is CWDM modules?

With the CWDM optical transceiver, different wavelength can be transmitted by only one core. And it’s receiver can receive signal from 1270nm-1610nm.

2. Where is the CWDM modules can be used?

As the below picture, the CWDM modules can be used in kind of solutions.

3.What is the MUX/DEMUX?

A: We often transmit and receive information with optical fibers. Because the optical fiber can help us sharing the information fastly, saving time and improving efficiency.

On the other hand, it also needs to use lots of optical fibers, so in order to save optical fibers. We use MUX/DEMUX, it will help us concentrate the different wavelengths of information on one optical fiber.

Then spread them to the different switch when they need to be used.

4.How many channels can be used in CWDM MUX/DEMUX?

A: 18 channels, from 1270nm-1610nm.(1270nm, 1290nm, 1310nm, 1330nm, 1350nm, 1370nm, 1390nm,1410nm,1430nm, 1450nm, 1470nm, 1490nm,1510nm, 1530nm, 1550nm, 1570nm, 1590nm,1610nm.)

It includes forward wavelength(1270nm-1450nm, it’s usually used to low rate, like 1.25G ), backward wavelength(1470nm-1610nm, it’s usually used to high rate, like 2.5G, 10G)

5.How do they work together?

The CWDM Modules were inserted into switches, and between the modules and MUX/DEMUX, they connect with patch cords. Because of the MUX/DEMUX, we can save lots of optical fibers.

6. What do you need in a normal solution?

a. Switches: More than 2. (Depends on what’s the application you working for.)

b. CWDM Modules(Dual fiber): 16

c. MUX-DEMUX: 2

d. Patch cords: 32 & 1 testing patch cord(with an attenuator.)

e. Optical fiber: 1

Base on different applications, the solutions are different. It involved the switch type, MUX/DEMUX channel number, etc.

In a word, If you can tell us the project you are preparing(application), or where will the MUX/DEMUX(CWDM modules) be used, we can offer you the most suitable solution you need.

For more detailed information, please visit www.htfuture.com

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

What are the differences between 25G DAC and AOC cable?

25G Ethernet has been hitting the web world at a sudden rate and may eventually become the fastest IEEE Ethernet standard ever completed.

25G cable is divided into 25G SFP28 direct attach cable and 25G SFP28 active optical cable, both of them can transmit data at 25Gbps. What are the differences between them?

HTFuture will focus on the differences between the two cables.

What is a 25G Direct Attach Cable?

25G DAC cable using silver conductor and foam insulation core, it has good attenuation performance and low delay performance, which make the signal transmission is correct, and can increase the transmission speed, is a short connection solution instead of the optical transceiver, the price is much cheaper than the same type of optical transceiver, in short distance connection applications has been widely welcomed.

What is a 25G Active Optical Cable?

25G AOC cable can be overcome the bandwidth limitation of traditional high-speed cable, and the 25G active optical cable can provide an ideal alternative solution for high-speed cable and short-distance SFP28 optical module, and the signal is more complete and higher performance. It is widely used in high-speed, high-density, and low-power data center networks.

What is difference in structure between 25G Direct Attach Cable and 25G Active Optical Cable?

The 25G DAC is made up of a copper cable and a fiber-optic transceivers at both ends. The connector is similar to the interface of the optical transceiver.But the connector modules on high-speed cables do not have expensive lasers, which greatly reduces the cost of short-range applications.

The 25G AOC consists of optical transceiver devices at both ends and composed of different length of OM3 or OM4 multimode optical fibers.The transceiver devices at both ends can provide the function of photoelectric conversion and optical transmission. This function ensures data transmission stability and application flexibility.

Compares to the 25G DAC, What are the advantages of 25G AOC?

1. The volume of 25G active optical cable is one-half of 25G high-speed cable, the weight is a quarter of it, so 25G active optical cable is much lighter than 25G high-speed cable;

2. 25G active optical cable also has better transmission performance and bit error rate, and the BER can reach 10–15;

3. 25G active optical cable has lower transmission power on the system link.

The 25G technology is the foundation of the 100G(4*25Gbps) Ethernet standard. Compared with the 40G technology, the 25G technology can provide higher port density and reduce cost, so the 25G technology has a promising prospect.

With the rapid development of 25G Ethernet technology, HTFuture has introduced two types of cables, 25G SFP28 DAC and 25G SFP28 AOC to meet the 25G network needs of customers. You can also select our 25G DAC cable or 25G AOC cable customized service according to your needs. 

For customized details, you can email to Ivy from HTFuture: sales6@htfuture.com.

How to Select Direct Attach Cable?

In today’s telecommunication market, high-qualified cables are always sought by users to satisfy the increasing demands of greater bandwidth and the growing amount of data transmission. As a result, direct attach cables have been designed to meet these requirements. Maybe you are not familiar with them and can’t determine which kind of direct attach cable is applicable for your networking servers. There is no need to worry. This post will introduce direct attach cables in details.

Definition of Direct Attach Cable

Direct attach cable (DAC), a kind of optical transceiver assembly, is a form of high speed cable with “transceivers” on either end used to connect switches to routers or servers. DACs are much cheaper than the regular optics, since the “transceivers” on both ends of DACs are not real optics and their components are without optical lasers. In storage area network, data center, and high-performance computing connectivity, they are preferable choice for their low cost, low power consumption and high performances.

Classifications of Direct Attach Cable

Direct attach cables can be divided into several types according to different standards. By Ethernet transmission rate and construction standard, 10G SFP+ cables, 40G QSFP+ cables, and 120G CXP cables are available. Classification according to the number of connectors is also feasible. Most DAC assemblies have one connector on each end of the cable, but there is a special kind of DAC assembly which may have 3 or 4 connectors on one end of the cable. Take QSFP+ to 4 SFP+ Passive Copper Direct Attach Breakout Cable for example, it features a single QSFP+ connector (SFF-8436) rated for 40-Gb/s on one end and 4 SFP+ connectors (SFF-8431), each rated for 10-Gb/s, on the other.

Based on material of cables used, there are direct attach copper cables and active optical cables.

Direct Attach Copper Cable — Direct attach copper cables are designed in either active or passive versions. The former provides signal processing electronics to avoid signal issue, thus to improve signal quality. What’s more, the former can transmit data over a longer distance than the latter which offers a direct electrical connection between corresponding cable ends. Nowadays, direct attach copper cables still have a place in market owing to their interchangeability, low cost and various data rates.

Active Optical Cable — Active optical cable (AOC) is one form of DAC. It integrates multi-mode optical fiber, fiber optic transceivers, control chip and modules. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable while mating with electrical interface standard. Compared with direct attach copper cable, its smaller size, electromagnetic interference immunity, lower interconnection loss and longer transmission distance make it popular among consumers.

Direct attach cables allow for greater bandwidth cost-effectively. As for which kind or kinds of DACs are suitable for network connectivity, it depends on specific situations. HTFuture supplies above-mentioned high-qualified DACs. Also, DACs can be customized in HTFuture to meet your different requirements.

More information about DACs, Welcome to conatct Ivy from HTFuture:

Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

CWDM Network: Technology Overview and Common Applications

Fiber exhaust is an inevitable problem constantly faced by carriers since the demand for higher speed bandwidth never ceases. The ever-improving wavelength division multiplexing (WDM) technology nowadays is increasingly used to boost network capacity, enabling carriers to deliver more services over their existing fiber infrastructure. CWDM, as one form of the mature WDM technologies, is a perfect fit for access networks and metro/regional networks. This article addresses the CWDM fundamentals and its common applications, and how CWDM helps to maximize network capacity effectively.

CWDM Technology at a Glance

Coarse wavelength division multiplexing (CWDM) came into prominence as a cost-effective alternative to maximize network capacity in the access, metro and regional network segments. It gains in more popularity in area with a relatively moderate traffic growth due to its simple deployment and low cost. ITU-T G.694.2 defines 18 wavelengths for CWDM transport ranging from 1270 to 1610 nm, spaced at 20 nm apart. But 8 wavelength in the 1470–1610nm band is mostly used since there exist high attenuation in the 1270–1450 nm band. This technology shines out in access network deployments by obtaining the advantages of flexible add-drop capacity and network design simplicity.

Common Applications of CWDM

After going through the basics of CWDM technology, this section will further explain its common applications. CWDM is primarily deployed in two areas: metropolitan and access networks. Let’s see how they could benefit from applying it.

Fiber Exhaust Relief

Fiber exhaust appears to be a severe problem that carriers endeavor to solve, especially for some metropolitan networks where data traffic increases continuously. Adding CWDM to the original optical network presents a cost-efficient and simple approach to this problem. In this case, carriers can add new services over a existing single optical fiber, while not interrupting service for existing customers. This solution is ideally suited for carriers that desires to increase the already installed network capacity without new fiber construction.

Enterprise LAN and SAN Connection

When interconnecting geographically dispersed Local Area Networks (LANs) and Storage Area Networks (SANs), CWDM rings and point-to-point links offer an optimum option. It is beneficial to integrate multiple Gigabit Ethernet, 10 Gigabit Ethernet and Fiber Channel links over a single fiber for CWDM point-to-point applications or for ring applications.

Adoption in Metro Networks With Lower Cost

4 channel CWDM system offers an ideal solution for smaller metro/regional markets which demand for moderate traffic growth. This configuration can expand the available capacity four times over an existing network, enabling less deployment cost than the commonly adopted 8 channel system. Meanwhile, the scalability of this 4 channel system also allows carriers to upgrade to 8 channel systems when the need occurs.

Central Office to Customer Premise Interconnection

Coarse WDM system is also well-fitted for metro-access applications such as Fiber to the Building (FTTB). Let’s take the most widely used 8 channel CWDM network for example, it is capable of delivering 8 independent wavelength services from the Central Office (CO) to multiple business offices located in the same building.

Combining With PON

Passive Optical Network (PON) is a point-to-multipoint optical network to deliver bandwidth to the last mile. It is cost-effective because it uses passive devices (splitters for example) instead of expensive active electronics. The issue exists in PON is that the amount of bandwidth they can support is rather limited. Since CWDM serves to multiple bandwidth, when combining it with PON, each additional lambda becomes a virtual point-to-point connection from a central office to an end user. If one end user in the original PON deployment needs his own fiber, adding CWDM to the PON fiber creates a virtual fiber for that user. Once the traffic is switched to the assigned lambda, the bandwidth taken from the PON is now available for other end users, so the access system can maximize fiber efficiency.

Conclusion

CWDM has clearly become the preferred method for increasing the bandwidth of metro/regional and optical access networks quickly, simply and at lowest cost. And it has proven to be sufficiently robust and reliable for upgrading the optical network to accommodate future growth. Hope this article could help to get a better understanding of coarse WDM technology.

HTFuture can provide you the full range of CWDM DWDM products that you need. If there is any inquiry, just let me know please.

Ivy: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

Reference Guide to Optical Transceiver Testing

As an integral part of the entire network, optical transceiver plays a significant role in deciding the overall performance and reliability of the network. The importance of optical transceiver testing therefore cannot be overestimated. Currently, since an increasing number of optical transceivers employed in networks is provided by third party suppliers, to ensure their compatibility and interoperability becomes more of a concern than ever. Well, this article is here to help you deliver effective optical transceiver testing.

Optical Transceiver Overview

Generally, an optical transceiver consists of a transmitter and a receiver. When a transmitter is connected with a receiver but the system doesn’t achieve your desired bit-error-ratio (BER), is there something wrong with the transmitter or the receiver? The transmitter and the receiver can affect each other, thus, specifications should guarantee that any receiver will interoperate with a worst-case transmitter, and any transmitter will provide a signal with sufficient quality such that it will interoperate with a worst-case receiver.

Precisely, defining worst case is often a complicated task. If a receiver needs a minimum level of power to achieve the system BER target, then that level will dictate the minimum allowed output power of the transmitter. If the receiver can only tolerate a certain level of jitter, this will be used to define the maximum acceptable jitter from the transmitter. In general, there are four basic steps for optical transceiver testing, as shown in the following picture, which mainly includes the transmitter testing and receiver testing.

Transmitter Testing

Transmitter parameters may include wavelength and shape of the output waveform while the receiver may specify tolerance to jitter and bandwidth. As an vital part in transceiver testing, testing a transmitter usually consists of two steps:

1. The input signal used to test the transmitter must be good enough. Measurements of jitter and an eye mask test must be performed to confirm the quality using electrical measurements.

 An eye mask test is a common method to view the transmitter waveform and provides a wealth of information about overall transmitter performance.

2. The optical output of the transmitter must be tested using several optical quality metrics such as a mask test, OMA (optical modulation amplitude), and Extinction Ratio.

Receiver Testing

Testing the receiver also serves as an essential part in transceiver testing. similarly, there are two steps:

1. Unlike testing the transmitter, in which case one must ensure that the input signal is of good quality, testing the receiver involves sending in a signal of poor enough quality. In this case, a stressed eye represents the worst case signal shall be created. This is an optical signal, and must be calibrated using jitter and optical power measurements.

2. The last step is to test the electrical output of the receiver. There are three basic categories we should follow:

• A mask test, which ensures a wide enough eye opening. The mask test is usually accompanied by a BER (bit error ratio) depth.
• Jitter budget test, which tests for the amount of certain types of jitter.
• Jitter tracking and tolerance, which tests the ability of the internal clock recovery circuit to track jitter within its loop bandwidth.

Conclusion

Complicated as it is, fiber optic transceiver testing is also an indispensable step to ensure overall network performance. As basic eye-mask test offers an effective and commonly used option for transmitter testing, testing the receiver can be more complex and requires more testing methods. A wide variety of fiber optic transceivers are available in Htfuture that are compatible with major brands on the market, such as Cisco, HP, IBM, Juniper, etc. Moreover, each fiber optic transceiver has been tested with the original-brand switch to ensure its high performance and superior quality. For more detailed information, please visit www.htfuture.com

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.

CWDM SFP vs DWDM SFP - Which One Suits You Better?

Overview of CWDM SFP

CWDM SFP is a kind of optical transceiver that utilizes CWDM technology. Similar with traditional SFP module, the CWDM SFP is a hot-swappable input/output device. It plugs into an SFP port or slot of a switch or router and links the port with the fiber-optic network. CWDM SFP transceiver modules make use of the SFP interface for connecting the equipment and use dual LC/PC fiber connector interface for connecting the optical network.

It is well known that CWDM SFP modules come in 8 wavelengths covering from 1470 nm to 1610 nm. Color markings on the devices identify the wavelength to which the Gigabit Ethernet channel is mapped.The following picture lists the CWDM SFPs with their wavelengths and color codes.

DWDM SFP Overview

DWDM (Dense Wavelength-Division Multiplexing) SFP transceivers are used as part of a DWDM optical network to provide high-capacity bandwidth across an optical fiber network, which is a high performance, cost-effective module for serial optical data communication applications up to 4.25Gb/s. There are 32 fixed-wavelength DWDM SFPs that support the International Telecommunications Union (ITU) 100-GHz wavelength grid. An inner structure of DWDM SFP is shown below.

Application

CWDM SFP transceiver is widely used in optical communications for both telecommunication and data communication. It is designed for operations in Metro Access Rings and Point-to-Point networks using Synchronous Optical Network (SONET), SDH (Synchronous Digital Hierarchy), Gigabit Ethernet and Fibre Channel networking equipment. The DWDM SFP can be also used in DWDM SONET/SDH (with or without FEC), but for longer transmission distance like 200km links and Ethernet/Fibre Channel protocol traffic for 80km links.

Which SFP Module Type Should You Choose: DWDM vs CWDM?

From a low-cost point of view, the CWDM SFP module is inexpensive than DWDM SFP. It provides a convenient and cost-effective solution for the adoption of Gigabit Ethernet and Fibre Channel. On the other hand, the key in selecting DWDM vs CWDM SFP modules lies in the differences between CWDM and DWDM. They refer to different methods of splitting up the light. For example, CWDM uses broader spacing between channels, allowing for inexpensive SFPs, and DWDM uses denser channel spacing, which allows for more wavelengths to be used on a single fiber. DWDM is typically used in large optical networks over the longer distance. Thus if you are looking for SFP modules over long distance and with better scalability, DWDM SFP module is the ideal choice.

Conclusion

I hope this brief introduction to DWDM vs CWDM SFP modules is helpful for you to make a choice in selecting them. Based on the Cisco CWDM SFPs, HTFuture CWDM SFPs are multi-rate transceivers, supporting data rates from 100 Mbps up to 4 Gbps. Besides, they support transfer distance at 20–40km, 40–80km and 80–120km in different colors, diversely satisfy the requirements of clients. All the DWDM SFP modules meet the requirements of the IEEE802.3 Gigabit Ethernet standard. They are suitable for interconnections in Gigabit Ethernet and Fibre Channel environments.

HTFuture aim to be your Reliable Partner for different kinds of Compatible transceiver (QSFP28, QSFP+, SFP, XFP, SFP+ etc) | OTN optical transmission system|DWDM Mux Demux|OADM | OTU | EDFA | NMS | DCM | OLP | OBP etc| More information, welcome to contact Ivy, contact Ivy. Email: sales6@htfuture.com Skype: live:sales6_1683

HTFuture team are ready and happy to assist you.