Tag Archives: OM3

How to Select the Right Fiber Patch Cable for 40G QSFP+ Transceiver?

It is clear that most servers in data center can support Ethernet transmission of 40G and 40G QSFP+ transceivers are considered to be the most economical solution for 40G transmission in data center. However, to make all these devices run normally and effectively, fiber patch cables must be used to connect the fiber optic transceivers which are plugged in Ethernet switches which is shown in the following picture. As the structure of 40G transmission is more complex than ever, the select of patch cords for 40G QSFP+ transceiver becomes more difficult. This article will focus on how to select the proper patch cords for 40G QSFP+ transceivers in details.

switch connection

Let’s get straight to the point. Numerous things need to be taken into consideration for proper selecting the fiber patch cables for 40G QSFP+ transceivers in practical cabling. However, several factors should always be considered: the cable type of the patch cords, the connector attached on the ends of the patch cords, and the ports of the switches that need to be connected.

For the first factor to be considered is cable type. This is because of the transmission characteristic optical signals of the fiber optic. Optical signals performs different over different wavelength. And optical signals with the same wavelength performs totally different when they run through different types of cables.

A question that people might come across can illustrate the above point well. Can a 40GBASE universal QSFP+ transceiver working on wavelength of 850nm be used with OM1 patch cords? Usually, signals with wavelength of 850nm are transmitted over short distance. Thus selecting a multimode fiber patch cords would be more economical. However, OM1 patch cords, which are ususally suggested for 100Mb/s and 1000Mb/s, cannot support 40G transmission and the quality of the 40G transmission is bad. This is because the transmission distance reduced as the data rate raised. For this case, OM3 and OM4—the optimized multimode fiber optic cables for 40G transmission in short distance are suggested. OM3 can support 40G transmission up to 100 meters and OM4 can support 40G transmission up to 150 meters.

The second aspect should be considered is the connector type that attached on the both ends of the patch cords, which is usually decided by the interface of the 40G transceivers. Usually 40G QSFP+ transceivers for short distance are armed with MPO interface and for long transmission distance up to 10 km usually employ LC interface. However, there are several 40G QSFP+ transceivers do not follow this rule, like 40GBASE-PLR4 and 40GBASE-PLRL4. These transceiver with MPO interface can support transmission over long distance. The biggest characteristics of MPO connector is high density which seems perfectly satisfy the requirement of 40G transmission. However, for this kind of connect, the polarity becomes complex. Thus during the selecting of this types of patch cords. The polarity must be considered. For your reference, here offers another article which is informative about MPO polarity—”Understanding Polarity in MPO System”. The following pictures shows the commonly used 40G transceivers with MPO or LC interfaces.

QSFP+ transceivers

The third importance factors is the switch ports which is closely related to the applications. During the practical cabling, two situations are common. One is 40G QSFP+ to 40G QSFP+ cabling and the other is 40G QSFP+ to 10G SFP+ cabling.

For 40G QSFP+ to 40G QSFP+ cabling: for distance up to 100m, the 40GBASE-SR4 QSFP+ transceiver can be used with OM3 fiber patch cable attached with a MPO one each end. For distance up to 150m, the 40GBASE-SR4 QSFP+ transceiver can be used with OM4 fiber patch cable attached with a MPO one each end. For distance up to 10km, the 40GBASE-LR4 QSFP+ transceiver can be used with single-mode fiber with LC connectors. The picture above shows the transmission of 40GBASE-LR4 QSFP+ transceiver with LC connector over single-mode fiber.

For the 40G QSFP+ to 10G SFP+ cabling, fan out patch cable with MTP connector on one end and four LC duplex connectors on the other end is suggested (as shown in picture below).

MTP=8LC patch cords

In conclusion, three main factors must be considered are fiber optic cable type, fiber optic connector type and the switch port. In practical cabling, more should be considered. These three aspects are far from enough. However, Fiberstore can solve your problems with professional one-stop service including the cost-effective and reliable network designing and 40G products. You can contact sales@fs.com for more details.

Upgrade to High Data Rate Transmission With Parallel Optics

Parallel optics represent a type of optical communication technology as well as the devices on either end of the link that transmit and receive information which are also known as parallel optical transceivers. Compared with traditional optical communication, parallel optical communication employs a different cabling structure for signal transmitting aiming at high-data transmission for short reach multimode fibers that are less than 300 meters. Traditional fiber optic transceivers cannot satisfy the increasing demand for high speed transmission, like 40GbE, while parallel optics technology can be a cost effective solution for 40/100GbE transmission.

Comparison between parallel optics technology and the traditional serial optical communication would better explain what parallel optics is and the reason why it is a cost effective solution to high data rate transmission. The following of this article will offer the comparison between the two optical communication technology from two aspects: connectivity method and key components.

Connectivity Method

Literally, parallel optics and serial optics transmit signals in different ways. In traditional serial optical communication, on each end of the link, there are one transmitter and one receiver. For example, the transmitter on End A communicates to the receiver on End B, sending a single stream of data over a single optical fiber. And a separate fiber is connected between the transmitter on End B and the receiver on End A. In this way, a duplex channel is achieved by two fibers.

2-fiber duplex connection

While in parallel optical communication, duplex transmission is achieved in a different way. A signal is transmitted and received through multiple paths, thus, the parallel optical communication can support higher data rate than the traditional optical communication. This is because, the devices for parallel optic communication on either end of the link contain multiple transmitters and receivers. For instance, in 2010 IEEE 802.3ba approved the 40GBASE-SR4 physical-medium-dependent multimode parallel optical solution, which uses eight fibers to transmit four duplex channels each at 10 Gigabit Ethernet. In this case, four 10Gbps transmitters on End A communicate with four 10Gbps receivers on End B, spreading a single stream of data over four optical fibers at a total data rate of 40Gbps.

Key Components

The parallel optical communication transmitting signals over multiple fibers, which has great advantages over traditional serial optical communication. It also means that it requires different components to support its high data rate transmission.

Connector: As previously mentioned, duplex transmission in serial optical communication uses 2-fiber duplex connectors, like duplex LC connectors to link the optics with other devices, while in parallel optical communication, multi-fibers are used to reach a higher data rate. Thus, multi-fiber connectors, like 12-fiber MPO connectors are used to connect with other devices. MPO connector is one key technology support parallel optical communication. This connectivity method is showed in the following picture?(Tx stands for transmit; Rx stands for receive).

12-fiber MTP parallel connection

Optical transceiver light source: Another complementary technology for parallel transmission is the light source of parallel optics—VCSELs (Vertical Cavity Surface Emission Lasers). Comparing with the edge-emitting semiconductor lasers in the traditional optics, VCSELs have better formed optical output which enables them to couple that energy into optical fibers more efficiently. In addition, VCSELs emit from the top surface, they may be tested while they are part of a large production batch (wafer), before they are cut into individual devices, which dramatically lowers the cost of the lasers. The following chart is about the comparison between VCSELs and edge-emitting semiconductor lasers. Cheaper to manufacture, easier to test, less electrical current required, supporting higher data rate, parallel optics using VCSELs could be a better choice to reach 40/100GbE transmission compared with traditional serial optics.

VCSEL vs Edge-Emitting Laser
Feature VCSEL Edge-Emitting Laser
Power consumption 2-3 mW 20 mW
Beam quality/ease of coupling Better, round low divergence Fine, asymmetric
Speed 10 Gbps 1 Gbps
Temperature stability 0.06 nm/oC 0.25 nm/oC
Specral width 1 nm 1-2 nm
Speckle Low in an array High


Parallel Optics for 40/100GbE Transmission

IEEE has already included physical layer specifications and management parameters for 40Gbps and 100Gbps operation over fiber optic cable. Two popular parallel optics solutions for 40Gbps and 100Gbps over multimode fibers are introduced here. For 40G, 40GBASE-SR4 transceiver is usually used, which requires a minimum of eight OM3/OM4 fibers for a transmit and receive link (4 fibers for Tx and 4 fibers for Rx). 100GBASE-SR10 transceiver is for 100Gbps transmission, which requires a minimum of 20 OM3/OM4 fibers for a Tx/Rx link, 10 fibers are used for Tx and the other 10 are for Rx.

40BASE-SR4 and 100BASE-SR10


The capabilities and uses of parallel optics and MPO technology continue to evolve and take shape as higher-speed fiber optic transmission, including 40/100GbE. It is uncertain that parallel optical communication would be the trend in the future. However, many cabling and network experts have pointed out that parallel optical communication supported with MPO technology is currently a way to equip an environment well prepared for the 40/100GbE transmission.


OM1, OM2, OM3, OM4: Standardization of Multi-mode Fiber Optic Cables

Standardization in fiber optic industry is one of the most confusing areas for people who involved in the business. “OM” terminology in fiber optic technology is new to both users and fiber optic manufacturers. The letters “OM” stand for optical multi-mode, which is marked multi-mode optical fiber specifications. There are four standards in fiber optic terminology: OM1, OM2, OM3, OM4. This post is going to illustrate what they are.

According to ISO 11801 standard, multi-mode fiber cables are described using a system of classification determined by OM1, OM2, and OM3. OM4 is a laser-optimized, high bandwidth 50µm multi-mode fiber. In August of 2009, TIA/EIA approved and released 492AAAD, which defines the performance criteria for this grade of optical fiber. While they developed the original “OM” designations, IEC has not yet released an approved equivalent standard that will eventually be documented as fiber type A1a.3 in IEC 60793-2-10.

OM1 cable typically comes with an orange jacket and has a core size of 62.5 micrometers (µm). It can support 10 Gigabit Ethernet at lengths up 33 meters. It is most commonly used for 100 Megabit Ethernet applications.

OM2 also has a suggested jacket color of orange. Its core size is 50µm instead of 62.5µm. It supports 10 Gigabit Ethernet at lengths up to 82 meters but is more commonly used for 1 Gigabit Ethernet applications.

OM3 has a suggested jacket color of aqua. Like OM2, its core size is 50µm, but the cable is optimized for laser based equipment that uses fewer modes of light. As a result of this optimization, it is capable of running 10 Gigabit Ethernet at lengths up to 300 meters. Since its inception, production techniques have improved the overall capabilities of OM3 to enable its use with 40 Gigabit and 100 Gigabit Ethernet up to 100 meters. 10 Gigabit Ethernet is its most common use.

OM4 also has a suggested jacket color of aqua. It is a further improvement to OM3. It uses a 50µm core but supports 10 Gigabit Ethernet at lengths up 550 meters and it supports 100 Gigabit Ethernet at lengths up to 150 meters.

OM 1234

Higher bandwidth requirements have accelerated 40 and 100 Gb/s applications. OM4 effectively provides an additional layer of performance that supports these applications at longer distances, thereby limiting the number of installations truly require OS2 single-mode fiber. OM4 can provide a minimum reach of 125m over multi-mode fiber within the 40 and 100 GbE standards.

Standardization of OM used not only for fiber optic cables but also fiber patch cables. Multi-mode 50 125 duplex fiber patch cable LC-LC provides 10 gigabit data transfer speeds in high bandwidth applications via 50/125µm laser-optimized OM4 fiber. They are 5 times faster than standard 50um fiber cable and work with both VCSEL laser and LED sources.