Tag Archives: EDFA

How to Save Cost for 500Gbps Metro Network Over Long Distance?

Increasing bandwidth has always been the most important task of telecom engineers. Through decades of research and engineering effort, 40Gbps and 100Gbps solutions have been used for network applications. But 40G and 100G transceivers can’t support too much long distance (QSFP-40G-ER4 for 40 km, QSFP-100G-LR4 for 10 km). How to extend the 500Gbps link to thousands of kilometres in Metro network within limited budget?

Save Fibre Cost–500Gbps Over Single Fibre Cable

Fibre cable cost takes a certain percentage in the whole network budget. Point to point connection needs many cables, while WDM technology take well care of this issue. In a metro network, usually multiple 10Gbps signals are transmitted by the use of DWDM Mux/Demux over a single fibre cable, which can save lots of money on multiple fibre cables and cable management issues. Then how to save cost to transmit 500Gbps signals over single fibre cable?

It sounds unbelievable. But we have the cost-effective solution. As we know, it will cost too much to replace all the current network system for upgrading to higher data rate. To save cost for increasing bandwidth, some producers add an extra port on DWDM Mux/Demux and that is 1310nm or 1550nm port. This port supports 1310nm or 1550nm transceiver. With such port, you can add 1G/10G/40G/100G to the existing DWDM network. For instance, we use 40-channel C21-C60 dual fibre DWDM Mux/Demux with 1310nm port and 1310nm band port for 1G/10G/40G/100G “grey” light. Plug 10G DWDM SFP+ transceivers into 40 channels, the overload is 400Gbps. Once plugging a 1310 40G QSFP+ LR4/ER4, then the total link reach up to 440G (400G + 40G). If install a 100G QSFP28 LR4 transceiver into 1310 port, the whole transport will be 500Gbps (400G + 100G). See this solution realize the goal of saving cost to run such huge network load over a single fibre.

500g dwdm network

40ch dwdm mux-demux

Extend 500G Transmission Distance

Since 500G signals can be transmitted over a single fibre cable, we have another issue to be solved. 500G transmission distance is needed far more than few kilometres in real life, maybe thousand of kilometres. How to extend the transmission distance?

According to IEEE standard, LR4 and ER4 transceivers can support the reach of 10 km and 40 km in the in ideal conditions, not considering fibre loss or connector loss. To extend 500Gpbs transmission distance, we need SOA (Semiconductor Optical Amplifier) and EDFA (Erbium Doped Fibre Amplifier). Add an SOA to support 40G/100GBASE-LR4 transceiver (over 1310 nm). The SOA is used to amplify incoming (Rx) signal on the receiving side of the link. So that the distances can reach up to 60 km. In 10Gbps DWDM networks, the signal transmission distance can be extended to hundreds of kilometres by the use of and EDFA (Erbium Doped Fibre Amplifier).

500g dwdm network-1

Recommended DWDM Solutions for 500Gbps Metro Network
ID# FS Part Number Description
35887 40MDD-1RU-A1-FSDWDM 40 Ch 1RU Duplex DWDM MUX DEMUX C21 to C60 with 1310nm Port and Monitor Port
31533 DWDM-SFP10G-80 10GBASE 100GHz DWDM SFP+ 80km, LC Duplex Interface, C21 to C60
14599 DWDM-XFP10G-40 10GBASE 100GHz DWDM XFP 40km, LC Duplex Interface, C21 to C60
14650 DWDM-XFP10G-80 10GBASE 100GHz DWDM XFP 80km, LC Duplex Interface, C21 to C60
24422 QSFP-LR4-40G 40G QSFP+ LR4 1310nm 10km, LC Duplex Interface
36173 QSFP-ER4-40G 40G QSFP+ ER4 1310nm 40km, LC Duplex Interface
51679 CFP2-LR4-100G 100G CFP2 LR4 1310nm 10km, LC Duplex Interface
36524 FMT26PA-EDFA 16dBm Output C-band 40 Channels 26dB Gain Booster EDFA

Summary

DWDM technology is very necessary to extend Metro Network reach. In this 500Gpbs Metro network, I have introduced very detailed cost-effective solutions. Remember all the indispensable DWDM equipment such as DWDM transceivers, DWDM Mux/Demux, EDFA, etc. For more information, please visit the site about FS.COM Long Haul DWDM Network Solution.

Related articles:

How to Extend 40G Connection up to 80 km?
Economically Increase Network Capacity With CWDM Mux/DeMux

Erbium Doped Fibre Amplifier (EDFA) Used in WDM System

The capacity of fibre optical communication systems has undergone enormous growth during the last few years in response to huge capacity demand for data transmission. With the available wavelength division multiplexing (WDM) equipment, commercial system can transport more than 100 channels over a single fibre. However, increasing the number of channels in such systems will eventually result in the usage of optical signal demultiplexing components with greater values of optical attenuation. Besides, when transmitted over long distances, the optical signal is highly attenuated. Therefore, to restore the optical power budget, it is necessary to implement optical signal amplification. This article may mainly tell you  why EDFA is used in WDM system and how does it work.

Why Use EDFA in WDM System?

EDFA stands for erbium-doped fibre amplifiers, which is an optical amplifier that uses a doped optical fibre as a gain medium to amplify an optical signal. EDFA has large gain bandwidth, which is typically tens of nanometres and thus actually it is enough to amplify data channels with the highest data rates. A single EDFA may be used for simultaneously amplifying many data channels at different wavelengths within the gain region. Before such fibre amplifiers were available, there was no practical method for amplifying all channels between long fibre spans of a fibre-optic link. There are practically two wavelength widows C-Band (1530nm-1560nm) and L-Band (1560nm-1600nm). EDFA can amplify a wide wavelength range (1500nm-1600nm) simultaneously, which just satisfies the DWDM application, hence it is very useful in WDM for amplification.

How Does EDFA Work ?

The basic configuration for incorporating the EDFA in an optical fibre link is shown in the picture below. The signals and pump are combined through a WDM coupler and launched into an erbium-doped fibre (EDF). The amplified output signals can be transmitted through 60-100km before further amplification is required.

EDFA
Erbium-doped fibre is the core technology of EDFA, which is a conventional silica fibre doped with erbium ions as the gain medium. Erbium ions (Er3+) are having the optical fluorescent properties that are suitable for the optical amplification. When an optical signal such as 1550nm wavelength signal enters the EDFA from input, the signal is combined with a 980nm or 1480nm pump laser through a wavelength division multiplexer device. The input signal and pump laser signal pass through erbium-doped fibre. Here the 1550nm signal is amplified through interaction with doped erbium ions. This can be well understood by the energy level diagram of Er3+ ions given in the following figure.

EDFA

Where to Buy EDFA for Your WDM System ?

To ensure the required level of amplification over the frequency band used for transmission, it is highly important to choose the optimal configuration of the EDFAs. Before you buy a EDFA, keep in mind that the flatness and the level of the obtained amplification, and the amount of EDFA produced noise are highly dependent on each of the many parametres of the amplifier. FS provide many kinds of EDFAs, especially the DWDM EDFAs (shown in the picture below), which have many output options (12dBm-35dBm). Besides, they are very professional in optical amplifiers. Whatever doubts you have, they can give a clear reply.

EDFA

Optical Amplifier Is a Key Technology for Restoring Signals

Optical communications are more and more prevailing for the high demand for telecommunication, video and data transmission. The optical fibre is capable of transmitting many signals over long distance to meet people’s various requirements. But the signals are easily attenuated in the long-distance high speed networks. Amplifiers are a key enabling technology for strengthening optical signals. Electrical amplifiers are originally used but gradually replaced by optical amplifiers.

Optical amplifier is a device that can amplify optical signals directly without the need to convert them into electrical ones. Electrical amplifier is originally used but gradually replaced by optical amplifier. It is a much cheaper solution in comparison with electrical amplifier which has costly conversions from optical to electrical signal. The longer the transmission distance is, the more electrical signals need to be converted, which makes the cost of electrical amplification higher and higher. So optical amplifier is used in an increasing number. More detailed information about it is as followed.

Optical amplifiers can be used as power boosters, in-line amplifiers and detector pre-amplifiers in fibre optical data links. Booster amplifiers are used to increase the optical output of optical transmitters when signals haven’t entered the optical fibres. Once transmitted, the optical signals are attenuated by 0.2dB/km. In-line amplifiers are then used to restore the optical signals to its original power level. At the end of the data link are pre-amplifiers which are used to increase the sensitivity of an optical receiver.

optical ampplifier functions

optical amplifier: functions

There are three most important types of optical amplifiers including erbium-doped fibre amplifier(EDFA), semiconductor optical amplifier (SOA) and Raman amplifier. Here will introduce them briefly.

Erbium-Doped fibre amplifier: it is an optical or IR repeater that amplifies a modulated laser beam directly without optical to electrical conversion. It uses a short length of optical fibre doped with the rare-earth element erbium. The signals-carrying laser beams are usually at IR wavelengths with application of external energy. It has low noise and capable of amplifying many wavelengths simultaneously, which is an excellent choice in optical communications.

Semiconductor optical amplifier: it is an optical amplifier which uses a semiconductor to provide the gain medium. The gain medium is undoped InGaAsP. This material can be tailored to provide optical amplification at wavelengths near 1.3 µm or near 1.5 µm which are important wavelengths for optical communications. It makes fewer noises than EDFA and generates less handle power. But it is more suitable to be used in networks where the best performance is not required for it is less expensive.

Raman amplifier: it is an optical amplifier based on Raman gain created by Raman scattering, which works entirely differently from EDFA or SOA. Raman optical amplifier have two key elements: the pump laser and the directional coupler. The pump laser has a wavelength of 90 nm to 1500 nm. The circulator provides a convenient means of injecting light backwards in to the transmission path with minimal optical loss. Raman amplification occurs throughout the length of transmission fibre, which makes Raman amplifier known as distributed amplifier.

For more information about optical amplifier, please visit www.fs.com.

Low-cost Optical Amplifiers

Communications can be broadly defined as the transfer of information from one point to another. In optical fibre communications, this transfer is achieved by using light as the information carrier. There has become an exponential growth in the deployment and capacity of optical fibre communication technologies and networks over the past twenty-five years.

Optical technology is the dominant carrier of global information. It is also central to the realisation of future networks that will have the capabilities demanded by society. These capabilities include virtually unlimited bandwidth to carry communication services of almost any kind, and full transparency that allows terminal upgrades in capacity and flexible routing of channels. Many of the advances in optical networks have been completed by the advent of the optical amplifier.

In general, optical amplifiers can be divided into two classes: optical fibre amplifiers and semiconductor amplifiers. The former has tended to dominate conventional system applications such as in-line amplification used to compensate for fibre losses. However, due to developments in optical semiconductor fabrication techniques and device design, especially over the last five years, the semiconductor optical amplifier (SOA) is showing great promise for use in evolving optical communication networks. It can be utilised as a typical gain unit but also has many functional applications including an optical switch, modulator and wavelength converter. These functions, where there is no conversion of optical signals into the electrical domain, are required in transparent optical networks.

Low-cost Optical Amplifiers

Cost reduction of optical amplifiers is of increasing concern because of continual pressure on the pricing of optical networking equipment, because of changes in applications and network architectures which are extending the range of applications of amplifiers beyond the line amplifier repeaters of the core network, and because the dominant EDFA technology is not as easily amenable to cost reduction through integration as other technologies such as semiconductors.

Low-cost optical amplifiers will be used in the highest volume, most cost sensitive applications, such as metro and access network line amplifiers, single-channel amplification for high speed, advanced modulation format channels, cable television distribution booster amplifiers(CATV) , and ASE sources for WDM passive optical networks (PONs). The complementary technologies for low-cost amplifiers, such as semiconductor optical amplifiers, and erbium-doped waveguide amplifiers (EDFA), (EDWAs) are covered. EDFAs, which is the dominant technology, comprises multiple components with different features and is based on different technologies.

The challenges and opportunities for reducing the costs of the primary components of EDFAs and the labor costs of assembling EDFAs are discussed, EDWAs offer opportunities for cost reduction by integrating the features of many of the components required for optical amplifiers. However, the lower efficiency of converting pump-to-signal power in erbium-doped planar waveguides compared with erbium-doped fibre, poses an obstacle to the commercial realization of the potential cost advantages of EDWAs, A recent approach is the PLC erbium-doped fibre amplifier, in which many of the passive devices are integrated on a PLC but the gain is provided by an erbium-doped fibre. This approach combines the advantages of PLC integration with the performance and pump efficiency of erbium-doped fibre and is especially advantageous for complex amplifier architectures requiring various optical components.

FS DWDM optical amplifier modules provide multi-function, low noise, Erbium-Doped Fibre Amplifier (EDFA) solutions that are ideal for metro Dense Wavelength Division Multiplexing (DWDM) applications. This family of C-Band 40 channels optical amplifiers is part of the fibre driver optical multi-service platform solution.