How to Choose Single-mode Fiber?

The common sense is that fiber optic patch cable can be divided into singlemode and multi-mode types. As we all know, multimode fiber is often divided into OM1, OM2, OM3 and OM4. So what is about the multi-mode fiber? Actually, the division of the multi-fiber is kind of complex. There are two primary sources of specification of single-mode optical fiber. One is the ITU-T G.65x series, and the other is IEC 60793-2-50 (published as BS EN 60793-2-50). This article will only focus on the part of ITU-T G.65x that defines 19 different single-mode optical fiber specifications. You can see the different types and the evolution process of them in the below table, which can be the miniature of the evolution of transmission system technology from the earliest installation of single-mode optical fiber through to the present day.

Name Type
ITU-T G.652 ITU-T G.652.A, ITU-T G.652.B, ITU-T G.652.C, ITU-T G.652.D
ITU-T G.653 ITU-T G.653.A, ITU-T G.653.B
ITU-T G.654 ITU-T G.654.A, ITU-T G.654.B, ITU-T G.654.C
ITU-T G.655 ITU-T G.655.A, ITU-T G.655.B, ITU-T G.655.C, ITU-T G.655.D, ITU-T G.655.E
ITU-T G.656 ITU-T G.656
ITU-T G.657 ITU-T G.657.A, ITU-T G.657.B, ITU-T G.657.C, ITU-T G.657.D

After you have a basic knowledge of this, next we will discuss how to choose the right one for your project in terms of performance, cost, reliability and safety. And in order to make this question easier to answer, we will get down to the aspect of the differences between the specifications of the G.65x series of single-mode optical fiber families.

G.652

The ITU-T G.652 standard fiber is the most commonly deployed one. It comes in four variants (A, B, C, D). A and B have a water peak. C and D eliminate the water peak for full spectrum operation. The G.652.A and G.652.B fibers are designed to have a zero-dispersion wavelength near 1310 nm, therefore they are optimized for operation in the 1310-nm band. They can also operate in the 1550-nm band, but it is not optimized for this region due to the high dispersion. These optical fibers are usually used within LAN, MAN and access network systems. The more recent variants (G.652.C and G.652.D) feature a reduced water peak that allows them to be used in the wavelength region between 1310 nm and 1550 nm supporting Coarse Wavelength Division Multiplexed (CWDM) transmission.

G.653

G.653 fiber was developed to address this conflict between best bandwidth at one wavelength and lowest loss at another. It uses a more complex structure in the core region and a very small core area, and the wavelength of zero chromatic dispersion was shifted up to 1550 nm to coincide with the lowest losses in the fiber. Therefore, G.653 fiber is also called dispersion-shifted fiber (DSF). G.653 has a reduced core size, which is optimized for long-haul single-mode transmission systems using erbium-doped fiber amplifiers (EDFA). However, its high power concentration in the fiber core may generate nonlinear effects. One of the most troublesome, four-wave mixing (FWM), occurs in a Dense Wavelength Division Multiplexed (CWDM) system with zero chromatic dispersion, causing unacceptabdle crosstalk and interference between channels.

G.654

The G.654 specifications entitled “characteristics of a cut-off shifted single-mode optical fiber and cable.” It uses a larger core size made from pure silica to achieve the same long-haul performance with low attenuation in the 1550-nm band. It usually also has high chromatic dispersion at 1550 nm, but is not designed to operate at 1310 nm at all. G.654 fiber can handle higher power levels between 1500 nm and 1600 nm, which is mainly designed for extended long-haul undersea applications.

G.655

G.655 is known as non-zero dispersion-shifted fiber (NZDSF). It has a small, controlled amount of chromatic dispersion in the C-band (1530-1560 nm), where amplifiers work best, and has a larger core area than G.653 fiber. NZDSF fiber overcomes problems associated with four-wave mixing and other nonlinear effects by moving the zero-dispersion wavelength outside the 1550-nm operating window. There are two types of NZDSF, known as (-D)NZDSF and (+D)NZDSF. They have respectively a negative and positive slope versus wavelength. Following picture depicts the dispersion properties of the four main single-mode fiber types. The typical chromatic dispersion of a G.652 compliant fiber is 17ps/nm/km. G.655?fibers were mainly used to support long-haul systems that use DWDM transmission.

G.656

As well as fibers that work well across a range of wavelengths, some are designed to work best at specific wavelengths. This is the G.656, which is also called Medium Dispersion Fiber (MDF). It is designed for local access and long haul fiber that performs well at 1460 nm and 1625 nm. This kind of fiber was developed to support long-haul systems that use CWDM and DWDM transmission over the specified wavelength range. And at the same time, it allow the easier deployment of CWDM in metropolitan areas, and increase the capacity of fiber in DWDM systems.

G.657

G.657 optical fibers are intended to be compatible with the G.652 optical fibers but have differing bend sensitivity performance. It is designed to allow fibers to bend, without affecting performance. This is achieved through an optical trench that reflects stray light back into the core, rather than it being lost in the cladding, enabling greater bending of the fiber. As we all know, in cable TV and FTTH industries, it is hard to control bend radius in the field. G.657 is the latest standard for FTTH applications, and, along with G.652 is the most commonly used in last drop fiber networks.

wdm-principle

From the above analysis, we can learn that different kinds of single-mode fiber has different applications. Since G.657 is compatible with the G.652, some planners and installers are usually likely to come across them. In fact, G657 has a larger bend radius than G.652, which is especially suitable for FTTH applications. And due to problems of G.643 being used in WDM system, it is now rarely deployed, being superseded by G.655. G.654 is mainly used in subsea application. After reading this article, I hope you have a clear understanding about these single-mode fibers, which may help you make the right decision.

The Selling Price Of Fiber Optic Cable

In general, fiber optics cost from 1 to 5 percent more than standard copper wire and multimode fiber sells at a higher price than single-mode fiber.

Although single-mode fiber is by far the predominant fiber for telecommunications, multimode is used in short-reach applications, including for data centers and some other local area networking deployments, as well as for numerous specialized applications not for telecom, such as medical uses, imaging and some illumination.

Multimode is not cheaper than single-mode fiber. However, the inexpensive LEDs or vertical-cavity surface-emitting lasers (VCSELs) and detectors used to power it are generally less expensive than its single-mode fiber counterparts. The real growth potential is in data centers using VCSELs with multimode fiber. Optical component vendors that can use VCSELs to carry signals in duplex or multistrand multimode fibers may find a market in local area networks or the growing number of data centers throughout the world. Short-range links would appear to be perfect for multimode fibers.

Although konw multimode fiber is more expensive than single mode fiber, what are the other factors deciding the fiber optic cable price?

Fiber optic cable prices are different based on the different cable types, even for the same structure fiber optic cables, the prices may be different because of the different fiber counts, jackettypes, lengths, etc.

The cable design influences the cost of a fiber optic cable. A simple duct cable will be less priced than a direct buried cable, which needs extra protection to meet additional mechanical and environmental safety when the cable is used for direct buried application. A self-supporting type aerial cable may be more expensive than a duct and direct buried type cables. The number of sheaths affects the cost. The more the number of sheathing layers, the higher the cost of cable will be. Process cost and material cost increases drastically proportional to the number of sheathing layers.

It is not always the construction of a cable that decides the cost of a fiber optic cable. The quantity required and delivery also plays major role in the costing of a fiber optic cable. A more quantity, cable manufacturers will offer a cheaper price. When buying a fiber optic cable from fiber optic cable manufacturer, most probably if we approach a cable manufacturer with a requirement of fiber optic cable, they will ask the quantity and delivery time at first apart from the construction requirements.

Fiber optic cable prices from different fiber optic cable manufacturers are also not same, sometimes they may be quite different, even you are asking about the same structure cable, this may be because of the quality, but brand names may also affect the fiber cable prices.

As you know, Corning developed the first commercial optical fiber in 1970. Corning and OFS remain the No. 1 and No. 2 fiber optic cable makers in the world currently. Corning and OFS almost control every aspect of the optical fiber-making process, including extruding the glass from draw towers, doping it, cooling it, stringing it, testing it, marking it, and then either cabling it or shipping it to other cablers.

Another hidden factor influences fiber optic cable price is the market. If the demand is more and competitors are less, the price will be naturally higher.

Pre Order FAQs Regarding Buying Fiber Optic Cables

Fiber optic cable is a large, long-distance optical signal transmission unit, by means of which we can spread out the various optical signals with low attenuation rate to meet signals transmission needs between different fields. There are more than 15.000 varieties of fiber optic cables in the telecommunication field. Choosing the right fiber optic cable is extremely important for any installation. Purpose of the cable is to protect the fibers during installation and the service lifetime. This article is written to address your concerns regarding what types of fibers do you need, where they will be installed, and where to buy fiber optic cable.

buying fiber optic cables

 

What types of fiber should I choose and how many fibers?
It may be familiar for you that optical fibers are divided into two different mode which is multimode and single mode.
Single-mode has a core that is 8.3 microns in diameter. Single-mode fiber requires laser technology for sending and receiving data. With a laser used, light in a single-mode fiber also refracts off the fiber cladding. Single-mode has the ability to carry a signal for mile, making it ideal for telephone and cable television on providers.

Multimode fibers, as the name suggests, permits the signals to travel in multiple modes, or pathways, along the insides of the glass strand or core. It is available with fiber core diameters of 62.5 and a slightly smaller 50 micron. 62.5 micron multimode is referred to as OM1. 50 micron fiber is referred to as OM2, OM3 and the recently added OM4. OM4 has greater bandwidth than OM3 and OM3 has greater bandwidth than OM2.

While single-mode has a core that is 8.3 microns in diameter. Single-mode fiber requires laser technology for sending and receiving data. With a laser used, light in a single-mode fiber also refracts off the fiber cladding. Single-mode has the ability to carry a signal for mile, making it ideal for telephone and cable television on providers. Fifty micron OM3 fiber is designed to accommodate 10 Gigabit Ethernet up to 300 meters, and OM4 can accommodate it up to 550 meters. Therefore, OM3 and OM4 fiber are always chosen over the other glass types. In fact, nearly 80% of 50 micro fiber sold is OM3 or OM4

Except the fiber mode, the number of fibers are necessary to know. Usually, unless you are making patchcords or hooking up a simple link with two fiber, it is highly recommended that you include a number of spare fibers. Corporate network backbones are often 48 fibers or more. Most backbone cables are hybrids – a mix of 62.5/125 multimode fiber for today’s networks and single-mode fiber for future networks. If the slowest network planned today is as gigabit speeds, it might even be better to us the new 50/125 multimode fiber optimized for the laser sources used in gigabit networks.

Where they will be installed, indoor, outdoor or both?
Outdoor cables are designed to protect the fibers from years of exposure to moisture. Until recently, your only choice for outdoor cables was loose-tube, gel-filled cables. But now you can buy dry water-blocked cables similar to indoor designs that are easy to terminate without breakout kits, saving incredible amounts of time. In a campus environment, you can even get cables with two jackets: an outer PE jacket that withstands moisture and an inner PVC jacket that is UL-rated for fire retardancy. You can bring the cable into a building, strip off the PE jacket and run it anywhere, while normal outdoor cables are limited to 50 feet inside the building.
Indoor cables are what we called “tight-buffered” cables, where the glass fiber has a primary coating and secondary buffer coatings that enlarge each fiber to 900 microns – about 1 mm or 1/25- inch- to make the fiber easier to work with. These cables can be directly terminated.

The most popular cable for indoor use is distribution cable, which has a number of 900-micron buffered, color-coded fibers inside a single jacket. It’s the smallest and lightest cable, and each fiber is sturdy enough for direct termination. Another choice for indoor use is the breakout cable, which is just a bunch of simplex cables inside a common jacket for convenience in pulling and ruggedness.

Where to buy fiber optic cable
Once knowing what kind of fiber optic cables is needed, last but not least is to decide where to buy your required fiber optic cables. In the actual production of fiber optic cable, materials which is wearable, radiation proof and adaptable to temperature is very important. Good core material and the external packages. When buy fiber optic cable, qualification of the fibre optic cable manufacturers should been taken into consideration, choosing qualified and professional manufacturers will ensure you quickly get the problem resolved after the sale.

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