Akin to water flowing from a small pipe into a large pipe, gainers are essentially perceived increases in optical power that occur at splice points due to variations in fiber characteristics, including core diameter, numerical apertures, mode field diameters and backscatter coefficients.
What is a gainsharing plan? gainsharing examples.


What is the difference between a TDR and an OTDR?

Essentially an optical time domain reflectometer, OTDR is the equivalent of an electronic TDR, but for optical fibres. … It then receives and analyses the light that is scattered by Rayleigh backscatter or reflected back from points along the fibre.

What is Ghost in OTDR?

‘ Ghosts are false reflective events and can be difficult to distinguish because they are nonexistent events in the OTDR trace. The most common cause of ‘ghosts’ is an ‘echo’ of light reflected back and forth multiple times between strong real reflective events until it is attenuated to the noise level.

How does an optical time domain reflectometer work?

An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. … It injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered (Rayleigh backscatter) or reflected back from points along the fiber.

What is a gainer when found on an OTDR trace?

What are the Causes? Gainers can show up when using an OTDR to measure loss from one end of a fiber link, and they occur due to the way in which an OTDR measures reflected light along the length of the fiber.

What is reflection in OTDR?

Reflectance (which has also been called “back reflection” or optical return loss) of a connection is the amount of light that is reflected back up the fiber toward the source by light reflections off the interface of the polished end surface of the mated connectors and air.

What are the 2 basic event types on an OTDR trace?

OTDR Testing With Launch Cable In general, there are two types of dead zones—event dead zone (EDZ) and attenuation dead zone (ADZ). Event dead zone: the minimum distance between the beginning of one reflective event and the point where a consecutive reflective event can be detected.

What is dB loss in fiber optics?

Performance is measured in decibels (dB)1, similar to how sound is measured. This indicates how much power the light has as it moves through the cables. Since the real goal is to transmit 100% of the data, the most useful metric is how much of it gets lost in transit. This is called dB loss.

What is OFC OTDR?

An Optical Time Domain Reflectometer (OTDR) is a device that tests the integrity of a fiber cable and is used for the building, certifying, maintaining, and troubleshooting fiber optic systems.

What is attenuation in optical fiber?

In optical fibers, attenuation is the rate at which the signal light decreases in intensity. For this reason, glass fiber (which has a low attenuation) is used for long-distance fiber optic cables; plastic fiber has a higher attenuation and, hence, shorter range.

What is the average loss in fiber splice?

The observed average splice loss at 1310 nm is 0.054 dB with SD of 0.015 dB, while at 1550 nm the average splice loss and SD is 0.045 dB and 0.014 dB, respectively. The sample set included fibers with worst case MFD mismatch of 0.8 µm.

How can you tell if fiber optic cable is bad?

If you think you know which cable is bad, there is a quick and easy test you can do yourself with a laser pointer or bright flashlight. Simply shine the flashlight or laser pointer in to one end of the cable, if you don’t see the light come through the other end, the cable is broken and will need to be replaced.

Which wavelength is recommended for OTDR testing?

Generally speaking, 1625 nm is the preferred wavelength for monitoring legacy 1310/1550-nm systems, largely due to laser cost. The 1650-nm wavelength is recommended for CWDM, DWDM, XGS-PON, and TWDM-PON systems where the traffic wavelengths extend into the L-Band.

What is Tier two fiber testing?

Tier 2 fiber optic testing is used to pinpoint root-cause locations and the amount of loss and optical return loss (ORL) from each problem contributor and is performed selectively in addition to Tier 1 testing under specific conditions and situations.

How do you analyze OTDR results?

However, if the spliced fibers are mismatched, the splice may appear on the OTDR trace as a gain. Here’s an example. If a splice goes from a larger core fiber to a smaller one, the difference in backscatter coefficients will show on the OTDR as a gain in light.

What is OTDR dead zone?

The OTDR dead zone refers to the distance (or time) where the OTDR cannot detect or precisely localize any event or artifact on the fiber link. It is always prominent at the very beginning of a trace or at any other high OTDR reflectance event.

What is UPC and APC in fiber optic?

The main difference between APC and UPC connectors is the fiber endface. APC connectors feature a fiber endface that is polished at an eight-degree angle; UPC connectors are polished with no angle. … With UPC connectors, any reflected light is reflected straight back toward the light source.

What is Rayleigh scattering in optical fiber?

Rayleigh scattering is a common scattering optical phenomenon, named after the British physicist Lord Rayleigh. It is linear scattering of light at scattering centers which are much smaller than the wavelength of the light. … Scattering centers for Rayleigh scattering can be individual atoms or molecules.

What is span loss?

Span analysis is the calculation and verification of a fiber-optic system’s operating characteristics. … The overall span loss, or link budget as it is sometimes called, can be determined by using an optical meter to measure true loss or by computing the loss of system components.

What is a ghost fiber?

GhostFiber High Speed Internet operates on Fiber Optics, land-line/cable plant, Fixed Wireless, and Satellite services. No matter where you live GhostFiber can likely service your home or business. … No satellite dish, no cable box, and no appointment necessary.

Which diode is used in OTDR?

60mw-80mw 1310nm Pulse Laser Diode. It is widely used in OTDR system.

What is Visual Fault Locator?

A visual fault identifier or visual fault locator (VFI / VFL) is a visible red laser designed to inject visible light energy into a fiber. Sharp bends, breaks, faulty connectors and other faults will “leak” red light allowing technicians to visually spot the defects.

Is dB same as dBm?

dB quantifies the ratio between two values, whereas dBm expresses the absolute power level. dBm is an absolute unit, whereas dB is a dimensionless unit. dBm is always relative to 1mW, while dB is expressed in watts and can be relative to other powers.

What is the lowest attenuation dB of a 1 km length fiber?

Fiber TypeWavelengthFiber Attenuation /km (1)Multimode 62.5/125um850nm3.5 dB1300nm1.5 dBSingle Mode 9um1310nm0.4 dBSingle Mode 9m1550nm0.3 dB

How much insertion loss is too much?

The maximum data rate drops precipitously for a channel with higher losses. Without equalization, you can have up to -12 dB of insertion loss. However, with the application of equalization, it’s possible to have as much as -25 dB insertion loss at Nyquist and still have a link that performs quite well.

What is splicing machine?

Fusion Splicing: In fusion splicing a machine is used to precisely align the two fiber ends then the glass ends are “fused” or “welded” together using some type of heat or electric arc. This produces a continuous connection between the fibers enabling very low loss light transmission. (

What is dynamic range in optical fiber?

The Dynamic Range (DR) is the difference between the minimum and maximum signal that you can put through a link for a given traffic bandwidth. The minimum detectable signal (MDS) is usually assumed to be just above the system noise floor and the maximum signal level is the largest peak power without distortion.

What is V number in optical fiber?

“V Number” The Normalized Frequency Parameter of a fiber, also called the V number, is a useful specification. Many fiber parameters can be expressed in terms of V, such as: the number of modes at a given wavelength, mode cut off conditions, and propagation constants.

How many losses are there in optical fiber?

There are two basic loss mechanisms in optical fibres. These are absorption and scattering: 1. Absorption loss.

What is the difference between attenuation and absorption?

In Physics, the main difference between attenuation and absorption is that attenuation is the gradual reduction in the intensity of a signal or a beam of waves which is propagating through a material medium whereas the absorption is the way in which the energy of a photon is taken up by matter.

How many number of misalignment occur during fiber to fiber joining process?

ALIGNMENT LOSSES The principal source of loss in both connectors and splices is fiber-to-fiber end face misalignment. There are three types of misalignment loss which may occur individually or in combination. These are lateral misalignment, axial separation, and angular misalignment.

How can you prevent loss of bending?

Thus bending losses can be reduced by a tighter field distribution so that the field components decay faster for larger radii. The larger the NA of the fibre, the better is the field confined into the core and the lower are the bending losses.

Which thing produces highest loses in a single mode fiber?

Factory made single mode connectors will have losses of 0.1-0.2 dB and field terminated single mode connectors may have losses as high as 0.5-1.0 dB (0.75 dB, TIA-568 max acceptable). Bending is the common problem that can cause optical fiber losses generated by improper fiber optic handling.

Can fiber optic cable bend?

Bend radius is the curvature an optical fiber can bend without damage or shortening its lifespan via kinking. … The result of kinking the fiber is known as bend loss: a loss of signal strength that may compromise the integrity of the data transmission.

Are fiber optic cables fragile?

Fiber optic cable has typically been categorized as fragile,like glass, which the actual fiber is, of course. … The impurities absorb as much as 1,000 times more light than optical fiber and concentrate stresses that reduce its strength and can cause cracks.

Can you fuse fiber optic cable?

Splicing fibers is commonly used to rejoin fiber optic cables when accidentally broken or to fuse two fibers together to create a fiber that is long enough for the required cable run. There are two accepted methods of splicing fibers: Mechanical splicing. Fusion splicing.

What is the distance range of OTDR?

Wavelength1310 nm1550 nmDynamic Range35 dB40 dBTypical maximum OTDR measurement range80 km150 km

Can you OTDR multimode fiber?

Some multimode OTDRs are now usable for short length multimode premises cables but only if they are properly set up before use. … The launch cable also allows the OTDR to check the first connector on the fiber being tested. An OTDR must always be used with a launch cable that matches the fibers being tested.

What is the difference between 1310 and 1550?

If made properly, the cable assembly will test about the same at either 1310 or 1550. 1550 Insertion Loss results are generally better by a few hundredths of a dB, due to, in part, its lower fiber attenuation. It’s normal that Insertion Loss values for a connector be ~0.01 – 0.05 dB better at 1550 than 1310.