What is the need of fiber testing to the 1625nm in the field? - Technopediasite

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Saturday, September 29, 2018

What is the need of fiber testing to the 1625nm in the field?

We all knows for many years, the transmission wavelengths were only 850nm, 1310nm and 1550nm. But now question is arise that "what is the need of fiber testing to the 1625nm in the field"? Today I would like to write on this topic. It is clear that networks may not always be tested at this wavelength 1625nm because temperature generates more problems at 1625nm than for lower wavelengths.May be you have done fiber testing at 1625 nm but when and why this test can be done, may be this information will not be. Today I will explain about this test that "What is the need of fiber testing to the 1625nm in the field"?

Temperature generates more problems at 1625nm than for lower wavelengths.Temperature induced cable loss (TICL) can be detected at 1625nm more than at any other wavelength. This will generate more losses in the cable. One thing more I want to mention here that Current connectors, splices and components are neither designed nor optimized for the 1625 nm wavelength window. Consequently, reflections and bigger losses can then appear at this wavelength.
Bend located at 3040 m by the OTDR at1625 nm
OTDR Trace at 1625nm

What is the need of fiber testing to the 1625nm in the field?
The bending effect is not something new. When 1550 nm wavelength was first introduced and added to the 1310 nm transmission wavelength, the bending effect had to be analyzed.
Many optical fiber reportswith, for example, 1550 nm splice losses compared with 1310 nm splice losses, in order to detect possible bending effects are still to be seen. Now with the 1625nm wavelength, a similar picture emerges.

Microbend and macrobend issues
Microbend and macrobends are a common problem in installed cable because they can induce loss of signal.Microbend is due to a deviation of the core asmeasured from the axis
of the fiber. Many sources of stress can create microbends, such as:
 Irregularities during fiber manufacturing
 Manipulation of the fiber during cable manufacturing
 Installation operations and equipment (tie wraps, clamps)
Environmental stresses (pressure, hits)
Microbending is critical, as this has a strong impact on the loss versus wavelength.Conversely, macrobend is due to a large bend in the fiber (more than 2mm radius).

Possible L and U bands to be used:
 1565 – 1625 nm defined as the L band (Long)
1625 – 1675 nm defined as the U band (Ultralong)
if the L band (and of course the U band) is used, then loss testing becomes necessary at transmission wavelengths up to the upper limit of the band. This is the reason why new test equipment is now introducing 1625 nm testing. As the most important fiber parameters for network installation are still splice loss, link loss, ORL (optical return loss), it is necessary to get the associated test equipments.

Now question is arise that When should I test my links at 1625nm?
It is clear that networks may not always be tested at this wavelength. The three main circumstances in which the 1625 nm will be least required are :
Upgrade of current networks for DWDM with L (and U) band use or plan.
Installation of new fiber networks With new tools available, the additional time to perform 1625nm compared with current 1310/1550nm becomes small. This is driving installers to perform the test at those three wavelengths, for future proofing.
In-service testing this is a well known application used for remote fiber test systems (RFTS) and used for all types of networks. However, for maintenance purposes, and for classical non-L band transmission, or typical PON networks, if couplers are available in the network with open ends, then contrapropagation (for example OTDR measurement made at the opposite end of the transmission laser) testing can be performed at this 1625nm wavelength without perturbing the 1310/1550 nm transmission.

Dear friends I hope that you will be satisfied with the explanation about the "What is the need of fiber testing to the 1625nm in the field"?How do you feel about my post please drop me a message in comment box. If you have any suggestion or required more details about any topic you can put up your demands.

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