#stable 4 channel CWDM Demux

[katherinewangfs-blog]

Analysis of Power Budget and Link Distance in CWDM System

It can’t be denied that CWDM technology is a cost effective method to increase the capacity in the existing system, which can give different wavelengths to multiple optical signals and multiplex them for transmission through only one single fiber. Different from the DWDM system, the network using CWDM technology are deployed by passive components like passive CWDM Mux Demux, without the need of additional power, which makes CWDM system more commonly used. Do you also plan to build a CWDM system? If yes, you can check the following information for reference, which mainly analyzes the optical power budget in a CWDM system and calculates the CWDM link distance according to the power budget for smoothly deploying a CWDM system.

What’s Optical Power Budget?

Before deploying an optical network, it is very essential to calculate the optical power budget for better deployment. What’s optical power budget? It is just the amount of light available to make a successful fiber connection which can be calculated by analyzing the original output power of the transmitter and the required input power of the receiver. In details, we should firstly learn the optical power that is emitted by the source (also referred to Transmit Power) and the required power of the detector (also called Receiver Sensitivity). Using the first data to subtract the second one, you’ll get the data of the optical power budget which greatly determines the performance of the whole network link.

Here is the equation: Optical Power Budget = Transmit Power - Receiver Sensitivity.

How to Get the Optical Power Budget in a CWDM System?

To estimate the link distance supported by a CWDM system, the optical power budget should be calculated first, which can greatly determine the CWDM link distance. Here will show you a basic CWDM system under an ideal condition to clearly illustrate how to get the optical power budget. In this basic CWDM system, there is a optical transmitter which transmit power is -2 dBm and a optical receiver with -25 dBm receiver sensitivity. Hence, the optical power budget is 23 dB, as shown in the following equation.

Optical Power Budget = Tx Power - Rx Sensitivity = -2 dBm - (-25 dBm) = 23 dB

However, the mentioned CWDM system is just under an ideal condition without loss caused by the signal transmission. In a normal CWDM system, there are many components like passive CWDM Mux Demux, CWDM transceiver inserted. All these components cause insertion loss once they are inserted into the CWDM link. Therefore, when doing the optical power budget, all the loss should be taken into account for calculating the power budget exactly.

Here is more exact equation: Power Budget = Tx Power - Rx Sensitivity - Loss

To get the real power budget of a CWDM system, here offers a simple CWDM link which uses the -2 dBm optical transmitter, -25 dBm optical receiver and four passive CWDM Mux Demux with low insertion loss. Both the stable 4 channel CWDM Mux and stable 4 channel CWDM Demux in the link have 2.0 dB insertion loss, and other two are 8 channel ones feature 2.5dB insertion loss separately, as shown in the figure below. As a result, the total loss caused by the four passive CWDM Mux Demux is 9 dB, resulted from 2.5 dB + 2.0 dB+2.5 dB + 2.0 dB. Then we can get the total power budget, 14 dB. The calculation process is: Power Budget = Tx Power - Rx Sensitivity - Loss = -2 dBm - (-25 dBm) - 9 dB = 14 dB

How to Calculate the Link Distance in the CWDM System?

After knowing the optical power budget, let’s calculate the link distance of the CWDM system according to the following equation: Link Distance = Optical Power Budget/Fiber Attenuation. As there may be some other power loss caused by the factors that we didn’t consider like fiber aging, temperature and poor splice, we often subtract 2 dB buffer from the total optical power budget. Meanwhile, the fiber attenuation is changeable according to the wavelength, usually varying from 0.2 to 0.35 dB/km. In this case, we’ll use 0.35 dB/km as a typical data. Then we can get the link distance is about 34 km. The calculation process is Link Distance = Optical Power Budget/Fiber Attenuation = (14 dB- 2 dB)/0.35 dB/km.

Conclusion

This paper intends to illustrate how to calculate the optical power budget and estimate the link distance of a CWDM system according to the optical power budget, which allows for better budget of deploying the CWDM system and eliminates the unwanted or unnecessary issues which may happen in the system deployment. Besides, if you want to make a cost effective CWDM system, you are suggested to buy CWDM components like cheap passive CWDM Mux Demux, CWDM transceivers from FS.COM, which are of good price and quality.

[katherinewangfs-blog]

10G DWDM Network for Economically Expanding Capacity

It can’t be denied that for most users, the capacity and transmission data rate their 10G networks offer sufficiently meet their needs at present. However, for some users, their 10G networks are capacity-hungry that requires more and more fiber optical cables installed for carrying large data. Considering that the available fiber infrastructure is limited, the method of putting more cables would be infeasible or unsuitable once the infrastructure no longer fulfill the growing requirements. Is there any economical solution to solve this issue, except upgrading the network that would cost a lot? The answer is yes. In order to create new capacity at a relatively low price, WDM technology is come up with that enables virtual fibers to carry more data. Since WDM technology has been a cost effective solution to face the capacity-hungry issue, here will offer the economical DWDM SFP+ transceiver and DWDM Mux Demux solutions for you to build the 10G DWDM network, which enables bigger capacity to meet your network needs.

DWDM SFP+ Transceiver

The DWDM SFP+ transceiver is an enhanced version of DWDM SFP transceiver that can transmit signals at 10Gbps–the max data rate, mostly deployed in the dark fiber project in combination with the DWDM Mux Demux. Like other kinds of SFP+ transceivers, it is also compliant to the SFP+ MSA (multi-source agreement), designed for building 10G Ethernet network. However, the working principle of DWDM SFP+ transceiver is much more complicated than that of common SFP+ transceiver due to the DWDM technology.

Generally, the DWDM SFP+ transceiver has a specific tuned laser offering various wavelengths with pre-defined “colors” which are defined in the DWDM ITU grid. The colors of the wavelengths are named in channels and the wavelengths are around 1550nm. Its channels are commonly from 17 to 61 and the spacing between channels is always about 0.8nm. In fiber optical network, the 100GHz C-Band with 0.8nm DWDM SFP+ transceiver is the most commonly used one, while transceivers with other spectrum bands like 50GHz with 0.4nm spacing DWDM SFP+ transceiver are also popular with users.

According to the transmission distance, the DWDM SFP+ transceiver can be divided into two types. One is the DWDM-SFP10G-40 with an optical power budget of 15dB, and the other is the DWDM-SFP10G-80 with an optical power budget of 23dB. As we know, the bigger the optical power budget is, the longer the transceiver will support the 10G network. Hence, the DWDM-SFP10G-40 can transmit 10G signals at lengths up to 40 km, but the DWDM-SFP10G-80 is able to support the same network with a longer distance, 80 km. What should be paid attention to is that the transmission distance can be also affected by the quality and type of the DWDM Mux Demux, the quality and length of the fiber, and other factors.

DWDM Mux Demux

The DWDM Mux Demux is a commonly used type of fiber optical multiplexer designed for creating virtual fibers to carry larger data, which consists of a multiplexer on one end for combining the optical signals with different wavelengths into an integrated signal and a de-multiplexer on the other end for separating the integrated signal into several ones. During its working process, it carries the integrated optical signals together on a single fiber, which means the capacity is expanded to some extent. In most applications, the electricity is not required in its working process because the DWDM Mux Demux are passive.

Unlike the CWDM Mux Demux with 20nm channel spacing, the DWDM Mux Demux has a denser channel spacing, usually 0.8nm, working from the 1530 to 1570nm band. It is designed for long transmission, which is more expensive than CWDM Mux Demux used for short transmission. Meanwhile, it also commonly used the 100 GHz C-band DWDM technique like the DWDM transceiver. As for its classification, there are basically two types according to line type, dual fiber and single fiber DWDM Mux Demux, and six types according to the number of the channels, 4, 8, 16, 40, 44 and 96 channels DWDM Mux Demux. All these types of DWDM Mux Demux are available at FS.COM with ideal prices. To better understand the DWDM Mux Demux, here offers a figure of a stable 8 channel DWDM Mux Demux for your reference.

Conclusion

Taking the cost issue into consideration, deploying a 10G DWDM network is much more economical than upgrading your network from 10G to 40G/100G which almost requires changing out all the electronics in your network. The 10G DWDM network makes full use of DWDM technology to expand the network capacity, which creates virtual fibers to support more data signals. If your 10G network is also capacity-hungry, you are highly suggested to deploy 10G DWDM network to make new capacity. As for the related components the 10G DWDM network needs like transceiver and Mux Demux, you can easily find them at FS.COM. For instance, FS.COM offers the DWDM SFP+ transceivers compatible with almost every brand, including Cisco, Juniper, Brocade, Huawei, Arista, HP and Dell, which have been tested to assure 100% compatibility.

Originally source: http://www.chinacablesbuy.com/10g-dwdm-network-for-economically-expanding-capacity.html