Optical fiber cable or fiber optic cable is an assembly of multiple optical fibers covered with plastic protective jacket outside. The optical fibers are named so because they are carry light and do the job of transmitting signals generated from this light to the destined locations. The optical fiber cables can be deployed in internal as well as external settings and are designed in such a way as to withstand the typical conditions like heat, humidity, rodent attack and others. Here are some of the topics that one can study to have complete knowledge about the optical fiber cables.
I- Understanding the structure of optical fiber cable
If we break down the optical fiber cable to basic elements, we can find a core and a steel wire reinforced and supplemented with filler and the whole of this is encased inside a jacket. There are additional layers like buffer, water-proof sheath, insulated metallic wire and other components too that can help make these cables efficient even in typically worse conditions.
A fiber optic cable has main functional part in the form of the core that is actually carrying the light to complete signal transmission; all other components are simply used to provide support and protection to the core. This diagram can help understand the structure the better way:
First part – the core
The core of the fiber optic cable forms the central portion of the cable and is composed of silica glass. These strands are responsible for the transmission of optical signals and are 8μm in diameter if it is a single mode type; the fiber measures 50μm or 62.5μm if it is multi-mode type.
Cladding – the first layer after the core
The first layer that covers the core is made of glass and it immediately surrounds it. The core plus the cladding make a single glass fiber, solid in nature, and is responsible for the transmission of optical signal. The cladding measures 125μm approximately.
Primary Coating – the second covering of the core
Primary coating or the primary buffer forms the protective layer that covers core plus cladding. It does the job of providing mechanical support and its plastic make does not add much to the overall weight. The primary coating is designed in such a way as to avoid interference with the transmission of the light through two innermost layers.
Covering over primary coating - Strengthening layers or strength members
The strength members form the layer above primary cover and these are composed of a special yarn called Kevlar. This layer is responsible for making the fiber optic cable break-proof and enables hassle-free installation. They are added to the fiber optic cable to prevent the breakage of the fiber glass during installation. The Kevlar material is responsible for taking the strain when the cable is pulled through duct.
The outermost layer is the cable jacket which is available in a variety of materials. The material is chosen according to the site of deployment. The jacket offers mechanical support and full protection the core and cladding portion of optical fiber cable.
There are a various types of jackets differentiated on the basis of ratings: such as LSZH or Low Smoke Zero Halogen, OFNR or Optical Fiber- Nonconductive-Riser, OFNP or Optical Fiber-Nonconductive-Plenum. These ratings help choose the cable according to the site where these are to be used.
II - Different designs of fiber optic cables on the basis of their structure
The fiber optic cables have two distinct designs – loose-tube and tight-buffer. Both of these can be used for indoor as well as outdoor setting. Still, loose tube cables are more popularly used for outdoor installations while in-building installations are preferred to be done using tight-buffer type.
Type 1. Loose-tube cables
The loose-tube cables are designed with distinct color codings for easy identification. They have plastic material buffer tubes that form protective layer for optical fibers and a filler component made of gel material that makes it water-proof. This type is characterized by free movement and ability of fiber to contract and expand in response to changing temperature. Also, the incredible bending ability of loose-tube cables make them fit for constricted spaces.
Type 2. Tight-buffered cables
Tight buffered cables, as the name suggests, have buffer material and fiber closely attached to each other while the former wrapping the fiber completely. This is in exact contrast to loose-tube cables that have fiber and buffer material loosely fit. Such arrangement adds ruggedness to the cable structure and thus enables easy handling and seamless installation. The aramid yarn in these cables is placed outside the cable jacket or is made to cover each fiber optic jacket individually. In the latter case, these are referred to as sub-jackets.
GYTA can be described as loose tube stranding made of flooding jelly compound and Aluminum-polyethylene binding jacket and metallic strength member.
Standards followed are:
This optical cable follows YD/T 901-2009 standard meant for outdoor layer, stranded optical cable used in telecommunications
Armored Buried Optical Cable – GYTA53
This is the structure of an armored buried optical cable:
Armored buried optical cable, GYTA53 can be described as a loose tube stranding composed of flooding jelly compound, inner and outer jackets made of aluminum-polyethylene and steel-polyethylene respectively with metallic strength member. This optical cable type also conforms to YD/T 901-2009 standard laid out for outdoor layer stranded type optical cable applicable in telecommunications
Overhead optical cable - ADSS
This is the detailed look of interior of ADSS:
The Single protector ADSS style optical cable is loose tube stranding cable characterized by non-metal strength member, half dry water-sealant, outer jacket made of PE and Kevlar strength member.
ADSS is designed on the guidelines mentioned in GB/ T18899-2002 standard outlined for self-supporting dielectric optical cable
Traditional Drop Cable Bow-type or FTTX Drop Cable Variety - GJYXCH, GJYXDCH, GJYXFCH, GJYXFDCH
FTTX drop cable variety looks like this:
Description of GJYXCH – this cable of self supporting nature is composed of LSZH jacket and metallic strength member
GJYXDCH description – This self-supporting ribbon type optical fiber has LSZH jacket and metallic strength member
GJYXFCH description – It is different from others in having non-metallic strength member, this self-supporting optical cable also has LSZH jacket
GJYXFDCH description – This self-supporting optical fiber ribbon type cable has LSZH jacket and non-metallic strength member
The standard followed by bow type drop cable is YD/T 1997.1-2014 and it is ideal for access network
IV - Applications of optic fiber cables
A variety of applications utilized in a number of industries makes use of fiber optic cables. Some of the common applications and usages of fiber optic cables are:
The ability of transmitting data at very high rates makes fiber optic cables quite useful for internet services. These are very easy to manage, can carry loads of data, are quite flexible and quite lighter as compared to copper cables and thus, are being used prolifically in internet connections.
Making cross-border telephone call has become a quality affair with fiber optic cables. The users are able to enjoy faster connection and lag-free conversations with added clarity with the fiber optic cables being used in telecom networks.
High definition televisions are liked because of greater bandwidth and unmatched speed. This has become possible with the use of fiber optic cables in transmitting the audio-video signals. The copper wires used previously are totally replaced by optical cables that are cheaper as well as capable of delivering high performance.
Optic fiber cables have made file transfer easier between the computers. The networks can easily be spread across the buildings and their seamless coordination is the advantage that fiber optic cables offer.
Bio-medical research, dentistry and medical procedures
Medicine and scientific research are also making use of fiber optic cables. The prevalence of non-intrusive surgical procedures has become possible with the user of optical fiber cables. The procedure called endoscopy, for example, is carried out by passing light through the area to be scanned or operated inside the body making it possible to have better view without too many or too large incisions. Bio-medical research has also got the needed support in the form of fiber optic cables.
Fiber optic cables have made the decorative lighting quite economic as well as fascinating. Christmas tree decoration is making use of fiber optic cables too. Because of ease of use and better quality, the use of fiber optics in illumination has increased in the recent years.
Inaccessible places can be explored and checked easily now, thanks to fiber optic cables! Mostly, inspection of pipelines and other underground inspections on-site are using fiber optic cables.
Space and Military applications
These areas require high level of security of data while making transfer of information. Thus, data transfer has become safer and faster in this field with the help of fiber optic cables.
Fiber optic cables play an important role in the lighting and safety features of present day automobiles. They are widely used in lighting, both in the interior and exterior of vehicles. Because of its ability to conserve space and provide superior lighting, fiber optics is used in more vehicles every day. Also, fiber optic cables can transmit signals between different parts of the vehicle at lightning speed. This makes them invaluable in the use of safety applications such as traction control and airbags.
V - The Advantages and Disadvantages of Optical Fiber Cable
Important benefits of fiber optic cables
Fiber optic cables make use of glass which is way more abundant and less costly than copper. Thus, making fiber optic cables is a cost-effective choice and one can get more of these in limited budget.
Fiber optic cables can transmit more data per unit length. This accounts for its higher bandwidth which is a usable feature for many objectives.
• Longer connectivity due to minimal loss
Since fiber optic cables exhibit less loss of power, the signal can reach longer distances making it possible to achieve longer connectivity. As compared to copper cables that can deliver data only up to 100m, the fiber connectivity can extend up to 2km.
• Low EMI
Fiber optic cables have low electromagnetic interference. This makes it possible to use these cables in electrically noisy surroundings without any issues.
• Compact structure
The fiber optic cable is 30 times smaller is cross-sectional area as compared to copper. And its capacity to handle data is about 4.5 times more than the latter.
• Very light
Fiber optic cables are thinner and lighter than copper cables. These are therefore, more space-efficient and offer ease of installation due to less bulky form.
Since the optical fibers do not radiate electromagnetic energy, the interception of information is not possible. Even physically speaking, the fibers are not so easy to detect, thus, these offer added security to the transmission of data.
• Flexible and corrosion resistant
Fiber optic cables are known for higher tensile strength and better flexibility. These can achieve better bending radius and so can fit in restricted spaces. They are more corrosion resistant as compared to copper as glass is the basic material used in it.
Some shortcomings of Optical Fiber Cable
Not so easy to Splice
Splicing is a bit difficult thing to do with optical fiber cables. The light tends to get scattered too much and their physical are is limited too. Bending too much can cause breakage.
Need specialists for Installation, hence a bit expensive
Since the optical fiber cables are not as robust as the copper counterparts, these need specialists’ acumen to get installed. Installation also requires test equipment that may add to the cost.
Highly Susceptible to damage
The fiber optic cables are more prone to damage during installation or any other construction activity due to the small sized, compact fibers that go into their making. Due to their sophisticated nature, the fiber optic cable should be installed keeping the restoration and back up in mind.
Difficult to curve
Since the data transmission requires repeating at regular intervals, the process may not turn out to be smooth and loss-free if the fiber cables are made to wrap in curves of smaller size.
VI - Knowing difference among optical cable, cable and optical fiber
What differentiates cable from optical cable?
1. First difference lies in material which is fiber glass for optical cable while metal, mostly copper, for a cable.
2. Optical cable, unlike a cable, transmits optical signal.
3. Cables are mostly used for energy and low quality data transmission while the optical cable is dedicated to data transmission.
How optical fiber and optical cable differ
Optical fiber is the core and the actual medium that transmits light in a fiber optic cable; whereas, optical cable or optic fiber cable is made of bundle of optical fibers. Optical fiber cable is made of fiber, strength members and other protective elements that provide safety to the core fibers. Made of quartz glass, the optical fiber is brittle and made of lots of cores.