Tag Archives: single-mode

How to Select Fibre Patch Lead for 40G QSFP+ Modules?

As the speed changes from 1 to 10 Gbps and now increases from 10 to 40 Gbps and even 100 Gbps, data centres develop into more complex systems. So different optical technologies and cabling infrastructure are required. For 40G data rates, the special transceiver module is QSFP+ (Quad Small Form-Factor Pluggable Plus). To build 40G data centres, you need to select suitable fibre patch lead for 40G QSFP+ Modules. But how?

40G transmission network needs advanced switch, matched patch leads and transceiver modules. The quality of these connections can largely affect the reliability and stability of the whole 40G network. However, connectivity of 40G is much more complex than ever. Thus, selecting the proper fibre patch cables for 40G network is more difficult and becomes a big issue in 40G migration. As mentioned, QSFP+ transceivers are suggested for 40G, this article will provide as detailed as possible about fibre patch lead selection for 40G QSFP+ transceivers.

40G QSFP+ transceivers

Patch cable is very important to 40G network not only because the switch connections necessity, but also because of the transmission principle of the fibre optic signals and the high density trend of 40G transmission. Several important factors like cable, connector and switch port should be taken into account when selecting patch leads for 40G QSFP+ transceivers.

Single-mode or Multimode Fibre Patch Lead

Fibre patch lead is essential for the network performance. Optical signals perform differently when information transforms through the cables with different wavelengths. When people buy fibre optical patch leads for 40G QSFP+ transceiver, they often ask if a 40GBASE universal QSFP+ transceiver working on wavelength of 850nm can be used with OM1 patch leads. The answer is yes, but not suggested. Why? As the optical signal transmission distance gets shorter, the data rate increases. The transmission distance and quality would be limited by using OM1 optical cable with 40G QSFP+ transceiver. OM1 cable is only suggested for 100 Mb/s and 1000Mb/s transmission. Two upgraded cables—OM3 and OM4 are suggested for 40G QSFP+ transceivers in short distance.

IEEE has announced standards for 40G transmission in both long distance and short distance, which are 40GBASE-LR4 and 40GBASE-SR4. (LR stands for long reach and SR stands for short-reach and). For long reach, single-mode fibre is suggested for 40G transmission with the distance up to 10 km. For short reach, multimode fibre—OM3 (up to 100 metres) and OM4 (up to 150 metres) is suggested for 40G transmission. OM3 and OM4, which are usually aqua-coloured, are accepted economic solutions for 40G in short distance with lower insertion loss and higher bandwidth.

MTP or LC Fibre Patch Lead

The connector type of the patch leads should depend on the interface of 40G QSFP+ transceiver. Now there are two interfaces commonly adopted by 40G QSFP+ transceiver and they are MTP and LC. Usually 40G QSFP+ transceiver with MPO interface is designed for short transmission distance and LC for long transmission distance. However, several 40G QSFP+ transceivers like 40GBASE-PLR4 and 40GBASE-PLRL4 have MPO interfaces to support long transmission distance.

mtp and lc connectors for qsfp+

High density is the most obvious characteristic of 40G transmission, which is largely reflected in the MTP connectors on patch leads used with 40G QSFP+ transceiver. As QSFP+ transceiver uses four 10G channels, MTP cable which uses 4 pairs of fibres with can provide a time-save and stable solution for 40G QSFP+ transceivers.

Besides, 40G QSFP+ transceiver with LC interface is also available. This type of QSFP transceiver uses four lanes with each carrying 10G in 1310nm window multiplexed to achieve 40G transmission. For this type, patch cable with duplex LC connector should be used.

Switch Port

The importance of network flexibility gradually reveals as the speed of Ethernet increases. Cabling options for 40G network are 40G QSFP+ to 40G QSFP+, 40G QSFP+ to SFP+. It’s very common that 40G ports is needed to be connected with 10G port. In this case, fan out patch cable with MTP connector on one end and four LC duplex connectors on the other end is suggested.

Factors like single-mode or multimode fibre jumpers, fibre patch lead connector and switch port are important in selecting the right patch leads for 40G QSFP+ transceivers. They are closely related to the transmission distance, network flexibility and reliability of the whole 40G network. But in practical cabling for 40G QSFP+ transceivers, there are more need to be considered. Planning and designing takes a lot of time and may not achieve results good enough. However, FS.COM can solve your problems with professional one-stop service including the cost-effective and reliable network designing and 40G products.

What Can We Get From Fibre Cable Jacket?

Fibre optic cable is applied as the most advanced communication medium by more and more users. Compared with copper cable, it can support more and better optical signal transmission of voice, data, video, etc. and offer many other advantages. When purchasing fibre optic cables, you must see the cable jacket at first. So what information does the outside jacket tell? What type of cable jacket should you select? Come with me to find the secrets of fibre cable jacket.

Fibre Cable Jacket Introduction

Fibre optic cable is constructed very complicated from the inside core, cladding, coating, strengthen fibres to the outside cable jacket. The core made of plastic or glass is the physical medium for optical signal transmission. As bare fibre can be easily broken, cable outer jacket is needed for fibre protection. The cable jacket is the first line of moisture, mechanical, flame and chemical defense for a cable. Without the jacket, fibre optic cables are very likely to be damaged during and after installation.

fiber-cable-jacket

Fibre Cable Jacket Characteristics

In most situations, robust cable jacket is better because the environment above or underground may be harsh. For better applications, you’d better take cable jacket seriously. Cable jacket is not as easy as you think. There are many characteristics you need to consider. Except the flexibility, it should withstand very low and high temperature. Whether the cable jacket has the good features of chemical and flame resistance. All these characteristics depend on cable jacket materials.

Fibre Cable Jacket Materials

Cable jacket is made of various types of materials. As mentioned above, the cable jacket should stand the test of different environmental conditions, including the harsh temperature, the sun & the rain, chemicals, abrasion, and so on. The following shows several common cable jacket materials for your reference.

PE (Polyethylene)—PE is the standard jacket material for outdoor fibre optic cables. It has excellent properties of moisture and weather resistance. It also has the good electrical properties over a wide temperature range. Besides, it’s abrasion resistant.

PVC (Polyvinyl Chloride )—PVC is flexible and fire-retardant. It can be used as the jacket materials for both indoor and outdoor cables. PVC is more expensive than PE.

LSZH (Low Smoke Zero Halogen)—LSZH jacket is free of halogenated materials which can be transformed into toxic and corrosive matte during combustion. LSZH materials are used to make a special cable called LSZH cable. LSZH cables produce little smoke and no toxic halogen compounds when these cables catch fire. Based on the benefits, LSZH cable is a good choice for inner installations.

Fibre Cable Jacket Colour

Fibre cable jacket colour depends on the fibre cable type. Fibre cable includes single-mode and multimode types. For single-mode fibre cable (Blog about single-mode fibre cable please read my blog What Are OM1, OM2, OM3 and OM4?), the jacket colour is typically yellow. While for multimode cable ( more details on multimode fibre cable ), the jacket colour can be orange (OM1&OM2 cable), aqua (OM3 cable) and purple (OM4 cable). For outside plant cables, the jacket colour is black.

How to Choose Fibre Cables?

To choose a fibre optic cable depends on your own applications. I’ll talk about this from two sides of jacket colour and jacket material. The cable jacket colour is not just for good looking. Different colour means different fibre mode. Which one suits you the most, the yellow or orange fibre cable? You should know well about the colour codes before buying your fibre cables. What’s more, you should also consider the installation requirements and environmental or long-term requirements. Where will be your fibre cables installed, inside or outside the building? Will your cables be exposed to hash environment very long? This can help you decide which jacket material is the best.

Summary

As a popular data transmission medium, fibre cable plays an important role in communication field. To some degree, the success of fibre connectivity lies in a right fibre cable. How to buy suitable fibre optic cables? This article describes the method from cable jacket. When selecting fibre cable, many other factors still need to be considered. Hope you can get your own fibre cable.

Advice on Patch Cable Selection for Optical Transceiver

Fibre optic network connection can’t be achieved without optical transceiver and patch cable. Optical transceiver varies from transmission media, interface, transmission distance, data rate, and brand, for example, SFP for 1000Mbps, SFP+ for 10G, QSFP+ for 40G, CFP and QSFP28 for 100G. It’s not difficult to identify these optical transceivers. But when you connect the optical transceiver to the patch cable, many details need to be noticed. This article will give you advice on how to choose the suitable patch cable for your optical transceiver.

Transmission Media—Copper & Fibre

According to transmission media of fibre optic and copper, transceivers can be divided into two kinds, copper based transceivers and fibre optic based transceivers. MSA has defined several copper based transceiver like: 100BASE-T, 1000BASE-T and 10GBASE-T. Copper transceivers are available in GBIC, SFP and SFP+ form factors, which usually has an RJ45 interface. So Cat5/6/7 cables are typically used to connect with the transceivers. Maybe Cat8 will be researched and developed to support higher data rate up to 40G sooner or later.

optical-transceiver-rj45-interface

As to fibre optic transceivers, things are more complex. For that fibre optic transceivers require different fibre patch cords which have more types. Fibre patch cables cover single-mode and multimode. Single-mode patch cable can be classified into OS1 and OS2. While multimode cables can be divided into OM1, OM2, OM3, OM4 cable. Different cables are used in different applications. Single-mode cable can support long distance transmission and multimode cable for short distance link. If the transmission distance is shorter than 500 metres, multimode patch cable is suggested. For long distance transmission, single-mode transmission is suggested. You patch-cableshould also consider that the transmission data rate can also affect the transmission distance. Let’s look at the following point.

Supported Distance and Data Rate

MSA has defined a variety of transceivers that can support different transmission distances and data rates. When you buy a fibre optic transceiver, you will find the data rate, wavelength, distance, etc. on its labeling. The following table show the basic information of most often used transceivers and supported cable type.

Description Wavelengh Data Rate Cable Type Distance
SX 850nm 1G MM 500 m
LX 1310nm 1G SM 8 km
EX 1310nm 1G SM 40 km
ZX 1550nm 1G SM 70 km
SR 850nm 10G MM 300 m
LR 1310nm 10G SM 10 km
ER 1550nm 10G SM 40 km
ZR 1550nm 10G SM 80 km
SR4 850nm 40G MM 100 m
SR10 850nm 100G MM 100 m
LR4 1310nm 40G SM 10 km

As mentioned before, single-mode patch cable is better for long distance transmission and multimode patch cable for short distance transmission. Actually single-mode patch cords can be used for different data rates in both long and short distances. But single-mode fibre optic cable will cost more. To achieve reliable performance in short distances with cost effective solutions, you should know the performance of multimode fibre optic cables. The following chart provides the detailed transmission distances and data rates information for different multimode fibre optic cables over wavelength of 850 nm for your reference.

Fibre Type 1G 10G 40/100G
OM1 300 m 36 m N/A
OM2 500 m 86 m N/A
OM3 1 km 300 m 100 m
OM4 1 km 550 m 150 m
Transceiver Interfaces

The selection of patch cable for transceiver should also consider the interfaces through which patch cords is connected to the transceiver. In addition, transceiver usually used one port for transmitting and one port for receiving. Generally, fibre optic transceivers usually employs duplex SC or LC interfaces. However, for BiDi transceivers only one port is used for both transmitting and receiving. Thus, simplex patch cord is used with BiDi transceiver.

Some 40G/100GBASE QSFP+ transceivers used MTP/MPO interfaces, which should be connected to the network with multi-fibre patch cords attached with MTP/MPO connectors. If these ports are used for 40G to 10G or 100G to 10G connection, then fanout patch cable should be used. For example, a MTP to 8 LC fanout cable can splitter 40G data rate to four 10G data rate.

Summary

Next time when you select patch cords for your fibre optic transceivers, you can consider these factors like transmission media, transmission data rate and distance, transceiver interfaces. FS.COM offers a wide range of fibre optic transceivers and patch cords. Custom service is also available. Any problem, please contact us via sales@fs.com.

What Should You Know Before Using an OTDR?

OTDR, the optical time domain reflectometer, is the most important investigation tool for optical fibres. It’s applied in the measurement of fibre loss, connector loss and for the determination of the exact place and the value of cable discontinuities. It’s the only device which can verify inline splices on concatenated fibre optic cables and locating faults.

To know how to use OTDR for the fibre investigations, first you should know the structure and working principle of OTDR equipment. When a short light pulse transmits into the fibre under test, the time of the incidence and the amplitude of the reflected pulses are measured. The commonly used pulse width ranges from nanosecs to microsecs, the power of the pulse can exceed 10 mW. The repetition frequency depends on the fibre length, typically is between 1 and 20 kHz, naturally it is smaller for longer fibres. The division by 2 at the inputs of oscilloscope is needed since both the vertical (loss) and the horizontal (length) scales correspond to the one-way length.

jdsu-mts-4000-otdr

Besides, to use an OTDR successfully, you should also know how to operate the instrument. The following is about the experiences collected from some experienced people who use OTDRs during installation and for maintaining telecommunication networks.

Keep Connectors Clean

Before use OTDR, first, you should watch out if the connectors are clean. If it’s dirty, then clean it. Otherwise, it will make measurements unreliable, noisy or even impossible. What’s worse, it may damage the OTDR.

Check the Connector or the Patch Cord

Check whether the patch cord, the module, and the fibre under test are single-mode or multimode. To test the patch cord, activate the laser in the CW (Coarse Wavelength) mode and measure the power at the end of the patch cord with a power meter. This should be between 0 and – 4 dBm for most single-mode modules and wavelengths.

Set the Range

The range is the distance over the cable which the OTDR will measure. The range should be longer than the cable you are testing. For example, if your link is 56.3 km long, choose 60 km. For distances greater than approximately 15 km, make your first measurement in longhaul mode, otherwise use shorthaul.

Determine the Wavelength

Usually single-mode is set for 1310 nm or 1550 nm, and multimode is set for 850 nm or 1300 nm.

Averages of Noisy Traces

If the trace is very noisy, increase the number of averages. Usually 16-64 averages are adequate. To improve the signal to noise ration of the trace, the OTDR can average multiple measurements, but averaging takes time. So try to average over a longer time.

Realtime Mode

In this mode, you can modify parameters only if you stop a measurement explicitly. So it avoids you to erase a trace averaged over a long time by accident. You use realtime mode to check your connection, the quality of splices, and whether a fibre is connected. Start in automatic mode, then switch to realtime mode and select the most suitable parameters.

Adjust the Refractive Index

If you know the exact physical length of the fibre under test, you can measure the refractive index. Start with the refractive index 1.5000. Place a marker at the end of the fibre. Then select the refractive index function and adjust it until the displayed marker position is equal to the known fibre length. Then, the effective refractive index will be displayed.

Macrobending Loss

Single-mode fibres (1550 nm) are very sensitive to macrobending such as a tight bend or local pressure on the cable. It doesn’t always happen at this wavelength of 1310 nm. So characterise your link at both wavelengths.

OTDRs are invaluable test instruments. Maybe a small mistake will cause serious damage to this equipment. So before use it, you should better know it as detailed as possible to avoid any loss because of innocence and make full use of it in optical fibre events.

Related article:
How to Choose a Right OTDR?
OTDR Selection Guide