Fibre Optic Cables' demand continues to grow with ongoing and further development in the Fibre To The "X" – FTTX market. Demands for super fast broadband at home has fueled this unprecedented demand for Fibre. Government has invested millions in infrastructure to enable operators to develop there fibre networks. New methods to deliver infrastructure has resulted in the development of "Bend Insensitive Fibre" this has helped increase yield during deployment of micro ducts. Also, footway enclosures and SDU (Single dwelling Unit) MDU (Multiple) are more compact, tighter bend radius, less obtrusive and more tolerant of installation practices. Bend insensitive fibre (ITU G657) has had a significant effect on network designs and product selection.
Optical fibre is sensitive to stress. When fibre is stressed, it results in a loss of signal. At a specific pinch point/s, the light will refract and pass through the fibre's sidewall or cladding. If the number of stress/pinch points increased or became more acute, more light/signal would be lost. (See Fig 1) Therefore it is imperative to observe the bend radius of the Fibre & Fibre Cable. Understanding bend radius and the effect it can have on the performance of the network is paramount.
Bend radius is how tight/acute a Fibre or cable can be bent without causing stress or micro-cracking on the fibre, resulting in optical signal to refract. If the fibre is stressed light will refract, transmission will be reduced, and attenuation will increase all of which will compromise the network's performance (See Fig 2).
Note – we have the following:
Bend radius is how small or tight a cable can be safely bent without causing damage by creating micro cracks on the fibre, the and consequential loss of signal. Bending a fibre cable excessively after installation can cause the optical signal to refract and escape through the cladding. This loss of light transmission will increase attenuation, which could then compromise the performance and integrity of the data being transmitted. Every cable will have a minimum bend radius, but this will vary according to the cable design and application.
Bend Insensitive Single-mode Fibre (BISMF) released back in 2007 has had a significant impact on the Fibre Market. The object of a fibre connection is to transmit light from A – B with minimal loss. Bending cable and fibre can introduce micro-cracking/Micro bending where the light will refract out of the cladding. Light loss will occur attenuation will increase and performance compromised.
In BISMF/ G657, an additional layer is applied. This is a lower refractive index material that reflects back into the core any light loss due to refraction. This additional layer/ring is called the trench. (See Fig 3).
BEST / G657 offers significant flexibility from a design and deployment perspective. Helping to drive down costs and improve yield.
In 2007, a new type of "bend-insensitive" single-mode fibre was introduced. It can tolerate stress from bending, stretching or twisting, without minimal optical performance loss. Under ITU recommendation for G.657, they specify two classes of single-mode bend insensitive fibre:
The minimum bend radius of G.657. A1 fibres is 10mm, of the G.657. A2 and G.657.B1 fibres are 7.5mm and of the G.657.B2 fibres is 5.0mm on a G.657.B3 2.0mm Compared with a minimum bend radius of the standard single-mode G652 fibres, usually 20 mm. (See Fig 4).
Given the significantly improved bend characteristics of fibre - G657, which also translates into far more flexible cables. BISMF cables can be confidently installed with appropriate installation techniques for Internal/ OSP /FTTX & Data Centres etc. with new innovative designs for internal / OSP and patching.
New Cable designs: Innovation has taken advantage of BISMF with compact designs, high fibre counts in smaller diameter cables.
Examples: Micro Modules / EPFU / Micro cables / Drop cables / Ribbon
New Markets: The advent of G657 has made FTTX a practical possibility.
Reduced costs: Some benefits - Quicker to install, improved yield, higher densityand reduced space. The manufacturing cost differential between G652 & G657 is minimal, but the gains in yield and productivity are significant. Making the decision to go with G657 very easy.
Productivity: With BISMF the installation techniques are more tolerant of bendsgiving rise to quicker installations and a higher yield.
Splicing: The splicing techniques and equipment currently used with G652 can also be used on G657.
Performance: You can now deploy High bandwidth applications withConfidence. Safe in the knowledge that any micro bending will have little or no effect on performance.
The question which is often asked where we have legacy G652 fibre in a network is, are these fibres compatible from a performance and splicing perspective? The simple answer is YES. The propagation method has been improved. However, it is only one mode guided in the core the addition of the trench has little or no impact on performance.
BISMF optic cables offer many advantages over traditional G652 fibre cables.
Bend Radius of Fiber Optic Cable Fiber Optic Cable
Optical fibre is sensitive to stress. When fibre is stressed, it results in a loss of signal. At a specific pinch point/s, the light will refract and pass through the fibre's sidewall or cladding. If the number of stress/pinch points increased or became more acute, more light/signal would be lost. (See Fig 1) Therefore it is imperative to observe the bend radius of the Fibre & Fibre Cable. Understanding bend radius and the effect it can have on the performance of the network is paramount.
Understanding Bend Radius and its effects on Fibre & Fibre Optical Cables
Bend radius is how tight/acute a Fibre or cable can be bent without causing stress or micro-cracking on the fibre, resulting in optical signal to refract. If the fibre is stressed light will refract, transmission will be reduced, and attenuation will increase all of which will compromise the network's performance (See Fig 2).
Note – we have the following:
- Short Term Bend Radius: This is the Maximum bend radius during installation.
- Long Term Bend Radius: This is the most acute recommended bend radius after installation.
General rules about Bend Radius of a Cable?
Bend radius is how small or tight a cable can be safely bent without causing damage by creating micro cracks on the fibre, the and consequential loss of signal. Bending a fibre cable excessively after installation can cause the optical signal to refract and escape through the cladding. This loss of light transmission will increase attenuation, which could then compromise the performance and integrity of the data being transmitted. Every cable will have a minimum bend radius, but this will vary according to the cable design and application.
What Is Bend Insensitive Fiber Optic Cable?
Bend Insensitive Single-mode Fibre (BISMF) released back in 2007 has had a significant impact on the Fibre Market. The object of a fibre connection is to transmit light from A – B with minimal loss. Bending cable and fibre can introduce micro-cracking/Micro bending where the light will refract out of the cladding. Light loss will occur attenuation will increase and performance compromised.
In BISMF/ G657, an additional layer is applied. This is a lower refractive index material that reflects back into the core any light loss due to refraction. This additional layer/ring is called the trench. (See Fig 3).
BEST / G657 offers significant flexibility from a design and deployment perspective. Helping to drive down costs and improve yield.
Bend Insensitive Single-mode Fiber Optic Cable (BISMF)
In 2007, a new type of "bend-insensitive" single-mode fibre was introduced. It can tolerate stress from bending, stretching or twisting, without minimal optical performance loss. Under ITU recommendation for G.657, they specify two classes of single-mode bend insensitive fibre:
- G.657 A
- G.657 B
The minimum bend radius of G.657. A1 fibres is 10mm, of the G.657. A2 and G.657.B1 fibres are 7.5mm and of the G.657.B2 fibres is 5.0mm on a G.657.B3 2.0mm Compared with a minimum bend radius of the standard single-mode G652 fibres, usually 20 mm. (See Fig 4).
Given the significantly improved bend characteristics of fibre - G657, which also translates into far more flexible cables. BISMF cables can be confidently installed with appropriate installation techniques for Internal/ OSP /FTTX & Data Centres etc. with new innovative designs for internal / OSP and patching.
Advantages of BISMF in Fiber Optic Cable
New Cable designs: Innovation has taken advantage of BISMF with compact designs, high fibre counts in smaller diameter cables.
Examples: Micro Modules / EPFU / Micro cables / Drop cables / Ribbon
New Markets: The advent of G657 has made FTTX a practical possibility.
Reduced costs: Some benefits - Quicker to install, improved yield, higher densityand reduced space. The manufacturing cost differential between G652 & G657 is minimal, but the gains in yield and productivity are significant. Making the decision to go with G657 very easy.
Productivity: With BISMF the installation techniques are more tolerant of bendsgiving rise to quicker installations and a higher yield.
Splicing: The splicing techniques and equipment currently used with G652 can also be used on G657.
Performance: You can now deploy High bandwidth applications withConfidence. Safe in the knowledge that any micro bending will have little or no effect on performance.
Compatibility of BISMF G657 and traditional G652
The question which is often asked where we have legacy G652 fibre in a network is, are these fibres compatible from a performance and splicing perspective? The simple answer is YES. The propagation method has been improved. However, it is only one mode guided in the core the addition of the trench has little or no impact on performance.
BISMF optic cables offer many advantages over traditional G652 fibre cables.
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