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Fiber Link Power Budget: How to Make It Right?

Fiber Link Power Budget: How to Make It Right?

In optical communication system, fiber patch cables and optical transceivers are necessities to complete the pathway for optical signal, enabling data to transmit between devices. To ensure that the fiber system has sufficient power for correct operation, it is vitally important to calculate the span’s power budget. A solid fiber link performance assures the networks run smoother and faster, with less downtime. This article addresses the essential elements associated with link power budget, and illustrates how to calculate power budget effectively.

Power Budget Definition

Power budget refers to the amount of loss a data link can tolerate while maintaining proper operation. In other words, it defines the amount of optical power available for successful transmitting signal over a distance of optical fiber. Power budget is the difference between the minimum (worst case) transmitter output power and the maximum (worst case) receiver input required. The calculations should always assume the worst-case values, in order to ensure the availability of adequate power for the link, which means the actual value will always be higher than this. Optical power budget is measured by dB, which can be calculated by subtracting the minimum receiver sensitivity from the minimum transmit power:

PB (dB) = PTX (dBm) – PRX (dBm)

fiber link power budget

Why Does Power Budget Matter?

The purpose of power budgeting is to ensure that the optical power from transmission side to receiver is adequate under all circumstances. As data centers migrate to 40G, 100G and possible 400G in the near future, link performance becomes increasingly essential. Link failures would stir up a sequence of problems like system downtime, which equates to accelerated costs, frustrated users, deteriorated performance and increased total cost. While with appropriate power budgeting, a high-performance link can be achieved for better network reliability, more flexible cabling and simplified regular maintenance, which is beneficial in the long run.

Critical Elements Involved In Calculating Power Budget

When performing power budget calculation, there are a long list of elements to account for. The basic items that determine general transmission system performance are listed here.

link power budget vs. distance

Fiber loss: fiber loss impacts greatly on overall system performance, which is expressed by dB per kilometer. The total fiber loss is calculated based on the distance × the loss factor (provided by manufacturer).

Connector loss: the loss of a mated pair of connectors. Multimode connectors will have losses of 0.2-0.5 dB typically. Single-mode connectors, which are factory made and fusion spliced on will have losses of 0.1-0.2 dB. Field terminated single-mode connectors may have losses as high as 0.5-1.0 dB.

Number and type of splices: Mechanical splice loss is generally in a range of 0.7 to 1.5 dB per connector. Fusion splice loss is between 0.1 and 0.5 dB per splice. Because of their limited loss factor, fusion splices are preferred.

Power margin: power budget margin generally includes aging of the fiber, aging of the transmitter and receiver components, additional devices, incidental twisting and bending of the fiber, additional splices, etc. The margin is needed to compensate for link degradation, which is within the range of 3 to 10 dB.

How to Properly Calculate Power Budget?

Here we use the following example to demonstrate how to calculate power budget of an optical link: Example: the system contains the transmitter and receiver, the optical link contains optical amplifier, 4 optical connectors and 5 splices. The following table presents attenuation or gain of each components.

Tx power:   3dBm

Connector loss: 0.15dB

Splice loss: 0.15dB

Amplifier gain: 10dB

Fiber optic loss: 0.2 dB/km

fiber link power budget calculation

The total attenuation of this link PL is the sum of:

Fiber optic loss: (30 km + 50 km) ×0.2dB/km = 16 dB

Attenuation of connectors: 4×0.15 dB = 0.60 dB

Attenuation of splices: 5×0.15 dB = 0.75 dB

So PL = 16 Db + 0.60 Db + 0.75 Db = 17.35 dB

The total gain of the link is generated by optical amplifier, which is 10 dB in this case. So PG = 10 dB

Considering link degradation, power margin should be calculated as well. A good safety margin  PM = 6 dB

To select the receiver’s sensitivity at the end of the optical path, it is sufficient to rearrange and solve the equation. So:

Ptx – Prx < PL – PG + PM

Prx > Ptx – PL + PG – PM

Prx > 3 dBm – 17.35 dB +10 dB – 6 dB

Prx > -10.35 dB

The receiver should provide sensitivity better than -10.35 dBm.


With data centers migrating to 40G, 100G, 200G and even 400G, fiber link performance becomes more important than ever before. Understanding link power budget will help you optimize your fiber link design as well. In addition, high-performance cables, quality transceivers and high-performance installation practices also assist to ensure better link performance.

Difference Between Fiber trunk, Harness, and Patch Cables

Difference Between Fiber trunk, Harness, and Patch Cables

Pre-terminated fiber cables are considered as a convenient and cost effective solution for today’s fiber optic network, which help save up to 65% installation time. Pre-terminated fiber cables are generally divided into trunk cable, harness cable and patch cable. To many newbies, these classifications often make them confused. Don’t worry, this post will take you easy to understand the difference between them.

Fiber Trunk Cable

Fiber trunk cables are available with today’s required fiber types with MPO/MTP, LC and SC connectors. Trunk cable is generally used for data center infrastructures and backbone applications where cable distances are reasonably predictable and can be easily determined. In a word, it is used as backbone cabling.

trunk cable

Fiber Harness Cable

A fiber harness cable, also called fan-out or breakout cable, is a cable assembly used to break out an MPO/MTP trunk to discrete connectors (such as LC, SC, etc.), in order to feed in to active equipment. The most common configurations of fiber harness cables are 8-fiber MPO/MTP (QSFP+ standard) to 4 duplex LC, 12-fiber MPO/MTP to 6 duplex LC, and 24-fiber MPO/MTP to 12 duplex LC.

harness cable

Fiber Patch Cable

Fiber patch cable, also called fiber patch cord or fiber jumper, is a shorter length fiber cable that is usually used to make connections between a patch panel and active equipment or between two switch ports. According to the connection requirement, there is a variety of connector options for fiber patch cable, such as LC, SC, ST, FC, MPO/MTP, and so on.

patch cable

Do you have a better understanding of these three types of pre-terminated cables after reading the above contents? If not, write down your question in comment for further discussion.

SFP Plus Direct Attach Copper Cables

SFP Plus Direct Attach Copper Cables

What is SFP+ Direct Attach Copper Cable?

SFP+ direct attach copper cable, also known as Twinax Cable, is a SFP+ cable assembly used in rack connections between servers and switches. It consists of a high speed copper cable and two copper SFP+ modules. The Plus SFP module allow hardware manufactures to achieve high port density, configurability and utilization at a very low cost and reduced power budget.

Direct Attach Cable assemblies are a high speed, cost-effective alternative to fiber optic cables in 10Gb Ethernet, 8Gb Fibre Channel and InfiniBand applications. They are suitable for short distances, making them ideal for highly cost-effective networking connectivity within a rack and between adjacent racks. They enable hardware OEMs and data center operators to achieve high port density and configurability at a low cost and reduced power requirement.

Fiberwtore SFP+ copper cable assemblies meet the industry MSA for signal integrity performance. The cables are hot-removable and hot-insertable: You can remove and replace them without powering off the switch or disrupting switch functions. A cable comprises a low-voltage cable assembly that connects directly into two SFP+ ports, one at each end of the cable. The cables use high-performance integrated duplex serial data links for bidirectional communication and are designed for data rates of up to 10 Gbps. Similar to the fiber patch cables, the SFP+ direct attach cables are made up of a cable and two connectors, with the difference that connectors are the SFP+ transceivers instead.


Types of SFP+ Direct Attach Copper Cables

SFP+ Copper Cable assemblies generally have two types which are Passive and Active versions.

FiberStore SFP Plus Passive CableFiberStore SFP Plus Active Cable

1. SFP+ Passive Copper Cable
SFP+ passive copper cable assemblies offer high-speed connectivity between active equipment with SFP+ ports. The passive assemblies are compatible with hubs, switches, routers, servers, and network interface cards (NICs) from leading electronics manufacturers like Cisco, Juniper, etc..

2. SFP+ Active Copper Cable
SFP+ active copper cable assemblies contain low power circuitry in the connector to boost the signal and are driven from the port without additional power requirements. The active version provides a low cost alternative to optical transceivers, and are generally used for end of row or middle of row data center architectures for interconnect distances of up to 15 meters.


Applications of SFP+ Direct Attach Copper Cables

~ Networking – servers, routers and hubs
~ Enterprise storage
~ Telecommunication equipment
~ Network Interface Cards (NICs)
~ 10Gb Ethernet and Gigabit Ethernet (IEEE802.3ae)
~ Fibre Channel over Ethernet: 1, 2, 4 and 8G
~ InfiniBand standard SDR (2.5Gbps), DDR (5Gbps) and QDR (10Gbps)
~ Serial data transmission
~ High capacity I/O in Storage Area Networks, Network Attached Storage, and Storage Servers
~ Switched fabric I/O such as ultra high bandwidth switches and routers
~ Data center cabling infrastructure
~ High density connections between networking equipment


FiberStore SFP+ Direct Attach Copper Cables Solution

Our SFP+ twinax copper cables are avaliable with custom version and brand compatible version. All of them are 100% compatible with major brands like Cisco, HP, Juniper, Enterasys, Extreme, H3c and so on. If you want to order high quality compatible SFP+ cables and get worldwide delivery, we are your best choice.

For instance, our compatible Cisco SFP+ Copper Twinax direct-attach cables are suitable for very short distances and offer a cost-effective way to connect within racks and across adjacent racks. We can provide both passive Twinax cables in lengths of 1, 3 and 5 meters, and active Twinax cables in lengths of 7 and 10 meters. (Tips: The lengths can be customized up to the customers’ requirements.)


Features of FiberStore SFP+ Direct Attach Copper Cables

~ 1m/3m/5m/7m/10m/12m available
~ RoHS Compatible
~ Enhanced EMI suppression
~ Low power consumption
~ Compatible to SFP+ MSA
~ Hot-pluggable SFP 20PIN footprint
~ Parallel pair cable
~ 24AWG through 30AWG cable available
~ Data rates backward compatible to 1Gbps
~ Support serial multi-gigabit data rates up to 10Gbps
~ Support for 1x, 2x, 4x and 8x Fibre Channel data rates
~ Low cost alternative to fiber optic cable assemblies
~ Pull-to-release retractable pin latch
~ I/O Connector designed for high speed differential signal applications
~ Temperature Range: 0~ 70°C
~ Passive and Active assemblies available (Active Version: Low Power Consumption: < 0.5W Power Supply: +3.3V)


FAQ of FiberStore SFP+ Direct Attach Copper Cables

1. What are the performance requirements for the cable assembly?
Our SFP+ copper passive and active cable assemblies meet the signal integrity requirements defined by the industry MSA SFF-8431. We can custom engineer cable assemblies to meet the requirements of a customer’s specific system architecture.

2. Are passive or active cable assemblies required?
Passive cables have no signal amplification in the assembly and rely on host system Electronic Dispersion Compensation (EDC) for signal amplification/equalization. Active cable assemblies have signal amplification and equalization built into the assembly. Active cable assemblies are typically used in host systems that do not employ EDC. This solution can be a cost savings to the customer.

3. What wire gauge is required?
We offer SFP+ cable assemblies in wire gauges to support customers’ specific cable routing requirements. Smaller wire gauges results in reduced weight, improved airflow and a more flexible cable for ease of routing.

4. What cable lengths are required?
Cable length and wire gauge are related to the performance characteristics of the cable assembly. Longer cable lengths require heavier wire gauge, while shorter cable lengths can utilize a smaller gauge cable.

5. Are there any special customer requirements?
Examples of special customer requirements include: custom cable lengths, EEPROM programming, labeling and packaging, pull tab length and color, company logo, signal output de-emphasis, and signal output amplitude. We can custom engineer cables to specific customer system architecture.

Optical Transceiver Module Tutorial From Fiberstore

Optical Transceiver Module Tutorial From Fiberstore

What is an Optical Transceiver module?

Optical Transceiver is a computer chip that uses fiber optic technology to communicate between other devices. This is opposed to a chip that transfers information electrically through metal wires and circuits or by the process of using various wave forms to communicate data. An optical transceiver chip is an integrated circuit (IC) that transmits and receives data using optical fiber rather than electrical wire.

Optical transceivers are typically used to create high bandwidth links between network switches. With the optical transceiver you can also create data transmission links capable of long range transmission.

Tips: Click here to know about the jargons related to fiber optic transceivers.

Development of Optical Transceiver Modules

Optical transceivers play an important role in conveying information across communication channels for Ethernet systems. They act as the all-in-one objects that receive and convey inforamtion, similar to those found in radios and telephone systems. With an optical transceiver, networks save much more space and avoid the need of having a transmitter and receiver apart inside a network. Capable of transmitting information further and faster than older models, the newer transceivers continue to change the way transceivers are used and appear, making for smaller, more compact modules than before. Here is a simple development of the transceivers.

Earliest Modules
SFP Module is one of the earliest transceiver devices which were created for Gigabit Ethernet networks and were preferred for their hot-swappable abilities. GBIC, or Gigabit interface Converters, allowed networks the ability to transmit data across copper or fiber-optic channels, creating a more versatile device than transmitters and receivers. Of course, GBIC modules were also have defect, and many had size and compatibility issues that limited their ability to transmit data across particular distances and at certain wavelengths.

XENPAK Modules
XENPAK became the new standard transceiver with increased support across longer distances and for multiple wavelengths. Unlike GBIC transceivers that sent information across either copper or fiber optic channels, XENPAKs included support for both networks, creating a better, more flexible module. And unlike the bigger GBIC transceivers, XENPAKs were capable of conveying data across short and long distances due to their configuration settings located inside the devices. When utilizing a single-mode configuration, networks create a single ray of light to send data across a long distance, while they use a multimode setup to transmit information across short distances. Both single and multimode fiber optics were utilized by networks, creating the XENPAK device ideal.

10 Gigabit Ethernet
X2 Transceiver and XPAK that the older XENPAK modules could no longer keep up with, were made when the 10 Gigabit Ethernet standard took hold. The smaller, more flexible X2 and XPAK standards allowed for even more support for the different Ethernet standards and were capable of transmitting data across longer distances.

And when the 10G SFP (SFP Plus or SFP+) came into existence, the competing standards of X2 and XPAK couldn’t continue to control the market as they once had any more. SFP+ modules allowed for more configuration standards for networks, providing various wavelength and distance configurations for Ethernet.


Principle of Optical Transceiver Modules

Optical transceiver generally includes both a transmitter and a receiver in a single module. The transmitter and receiver are arranged in parallel so that they can operate independently of each other. Both the receiver and the transmitter have their own circuitry so that they can handle transmissions in both directions. The transmitter takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the transmitter is coupled into the fiber with a connector and is transmitted through the fiber optic cable plant. The light from the end of the fiber is coupled to a receiver where a detector converts the light into an electrical signal which is then conditioned properly for use by the receiving equipment.

In a word, the optical transceiver module is the role of the photoelectric conversion. The transmitter converts electrical signals into light signals, and through the fiber optic transmission, the receiving end of the optical signals are converted into electric signals.

How Optical Transceivers Work In Personal Computers

When there is an issue, the pieces that make up the personal computers could be a mystery for many people. Without having an established understanding, we can feel helpless and incapable of fixing even the most basic of problems on ourself. So, it’s necessary to make clear that how the transceivers work in the computers.

Considering that many of us are constantly on the internet, it may be easy to get an understanding of the most basic optical transceivers and how they make it so you can connect an search the internet with ease. To provide you with a straight connection to the web, you are either connected through a wireless network, or to an Ethernet cable which is connected to your modem or router when you are online. The Cat5 cable as it is also known, plugs into the computer by using the optical transceiver, which is often not housed on the side of your laptop, or the reverse end of the CPU.

There are many various modules that can be utilized as your optical transceiver. Unlike XFP modules, Cisco SFP modules, GigaBit interface converters, or GBIC modules, are some of your more average transceivers, and are input/output modules with one end that plugs into a gigabit ethernet port, while the opposing side is plugged into the fiber patch cables and links the fiber optic networks. Allowing the devices to process the data accordingly, the base function of the GBIC module is to communicate the signals between the Ethernet network and fiber optic network. One terrific aspect of the GBIC module is that it’s a hot pluggable, allotting for a port to be changed from one kind of external interface to another by simply plugging the module in to an alternate external interface without having to power down the host switch or router in the process.

Application of Optical Transceiver Modules

Optical transceiver, essentially just completed the converted of data between different media, can realize the connection between two switches or computers in the 0-120km distance. Its main function is to achieve the conversion between optical-electrical and electrical-optical, including optical power control, modulation transmission, signal detection, IV conversion and limiting amplifier decision regeneration. In addition, there are security information query, TX-disable and other functions. Here is a summary in the practical application.

1. Optical transceivers can realize the interconnection between switches.

2. Optical transceivers can realize the interconnection between the switch and the computer.

3. Optical transceivers can realize the interconnection between computers.

4. Optical transceivers can act as the transmission repeater.
When the actual transfer distance exceeds the nominal transmission distance of the transceiver, in particular, the actual transfer distance exceeds 120km alerts, with 2 sets transceiver back to back in the case of on-site conditions allow, repeaters or the use of “optical-optical” conversiona relay, is a very cost-effective solution.

5. Optical transceivers can offer conversion between single-mode and multimode fiber connection.
When the networks appear to need a single multimode fiber connection, you can use a multimode transceiver and a single-mode transceiver back-to-back connections, which can solve the problem of single multimode fiber converted.

6. Optical transceivers can offer WDM transmission.
The lack of resources of long-distance fiber optic cable, in order to improve the utilization rate of the fiber optic cable, and reduce the cost, transceiver and wavelength division multiplexer (WDM multiplexer) with the use of two-way information on the same fiber transmission.

Classification of Optical Transceiver Modules

Optical Transceiver modules can be classified according to the following aspects.

1. Optical Fiber Type
Single-mode fiber transceiver and Multimode fiber transceiver. The single-mode version has a transmission distance of 20 to 120 km, while the multimode one’s is 2 to 5 km. Due to the different transmission distance, the transceivers’ transmit power, receiver sensitivity and the use of wavelength will be different.

2. Optical Fiber Count
Simplex fiber transceiver and Duplex fiber transceiver. The simplex version receives the data sent in a single fiber transmission, While the duplex one receives data transmitted on a dual fiber transmission. By definition, single fiber devices can save half of the fiber, a fiber that is in the receive and transmit data, where the fiber is very applicable to resource constraints. These products use the wavelength division multiplexing techniques, mostly using the wavelength 1310nm and 1550nm.

3. Transmission Rate
Transmission rate refers to the number of gigabits transmitted per second, per unit of Mbps or Gbps. Optical modules cover the following main rate: low rates, Fast, Gigabit, 1.25G, 2.5G, 4.25G, 4.9G, 6G, 8G, 10G and 40G.

4. Package
SFP, SFP+, GBIC, XFP, XENPAK, X2, 1X9, SFF, 200/3000pin, XPAK
, etc. Click for Details About Related Packages.


FiberStore Optical Transceiver Custom Solutions

What You Should Think About Before Selecting Fiber Cables

What You Should Think About Before Selecting Fiber Cables

Sorting through cables and connectivity options could be a frustrating exercise. It’s hard enough working through the categories and levels of copper networking cables, where most cables end with similar connector. What happens when you start looking at fiber cables? This is where things can definitely get confusing! This article tells you how to select the right kind of fiber cables.

Let’s move on off by saying that fiber optic cables can be used in a huge variety of applications, from small office LANs, to data centers, to inter-continental communication links. The information lines that connect between North America and Europe, for example, are constructed with fiber optic cable strung underneath the ocean. Our discussion in this article will focus mainly on the kinds of cables present in those small-scale networks closer to home, and in particular to pre-terminated cables which may be designed for installation, called “patch cords”, “pre-terms”, or any other similar nicknames like fiber patch cables. Prior to you buying, you should make clear the following parameters.

Multimode and Single mode
One of the first things to determine when selecting fiber optic cables is the “mode” of fiber that you’ll require. The mode of a fiber cable describes how light beams travel within the fiber cables themselves. It’s important because the two modes aren’t compatible with each other, which means that you can’t substitute one for that other.
There’s really not much variety with single mode patch cords, but there’s for multimode. You will find varieties described as OM1, OM2, OM3 and OM4 (OM means the “optical mode”). Basically, these varieties have different capabilities around speed, bandwidth, and distance, and the right type to make use of will be based mostly upon the hardware that is being used with them, and any other fiber the patch cords will be connecting to.

Fiber Optic Cable Jackets
Pre-term fiber can be used in a variety of installation environments, and as a result, may need different jacket materials. The standard jacket type is called OFNR, which means “Optical Fiber Non-conductive Riser”. This can be a long-winded way of saying, there’s no metal in it, so it won’t conduct stray electrical current, and it can be installed in a riser application (going in one floor up to the next, for instance). Patch cords are also available with OFNP, or plenum jackets, which are ideal for use in plenum environments for example drop-ceilings or raised floors. Many data centers and server rooms have requirements for plenum-rated cables, and also the local fire codes will invariably have the final say in what jacket type is required. The ultimate choice for jacket type is LSZH, which means “Low Smoke Zero Halogen”, that is a jacket produced from special compounds that provide off very little smoke with no toxic halogenic compounds when burned. Again, seek advice from the neighborhood fire code authority to be certain of the requirements from the installation before making the jacket selection.

Simplex and Duplex
Simplex and duplex have only the difference between one fiber or two, and between one connector at each end of the cable, or two connectors each and every end. Duplex patch cords are the most common type, because the method in which most fiber electronics work is they need two fibers to speak. One is used to transmit data signals, and the other receives them. However, sometimes, just one fiber is required, so simplex patch cords may be essential for certain applications. If you aren’t sure, you can always be on the safe side by ordering duplex patch cords, and just one of these two fibers.

Fiber Optic Cable Connectors
Remember what we should said at first about copper category cables? No matter what level of twisted pair you were coping with (Cat 5, 5e, etc), you always knew you would be dealing with an 8-position modular RJ-45 plug around the end from the cable. Well, with fiber patch cords, there is a few possibilities when it comes to connectors. The common connector types are FC, LC, SC, ST and MTRJ etc..

These are the most typical selections that you will find when choosing amongst patch cords. If you’re able to determine which of these characteristics you need, it is highly likely you will make the right choice when custom fiber optic cables with suitable parameters.