What is attenuation formula in optical fiber?

Attenuation is the loss of optical power as a result of absorption, scattering, bending, and other loss mechanisms as the light travels through the fiber. The attenuation coefficient or attenuation rate α is given by α(dB/km) = A/L. Here L is the distance between points X and Y.

How is fiber optic attenuation measured?

The most accurate way of measuring the fiber attenuation coefficient requires transmitting light of a known wavelength through the fiber and measuring the changes over distance. The conventional method, known as the cutback method, involves coupling fiber to the source and measuring the power out of the far end.

What is the formula of optical Fibre?

Refractive index n1 of core is defined as: n1 = c / v, where c = 3×10 8 m/s is the speed of light in vacuum and v is the speed of in the core. Maximum size of angle t must be smaller than 21° in order to have total internal reflection at the core-cladding interface.

What is the formula of numerical aperture?

The “Numerical Aperture” (NA) is the most important number associated with the light gathering ability of an objective or condenser. It is directly related to the angle of the cone which is formed between a point on the specimen and the front lens of the objective or condenser, determined by the equation NA = n sin ∝.

What are the types of attenuation in optical fiber?

Attenuation on Optical Fiber (1) Intrinsic loss in the fiber material. (2) Scattering due to micro irregularities inside the fiber. (3) Micro-bending losses due to micro-deformation of the fiber. (4) Bending or radiation losses on the fiber.

What is the formula for attenuation?

The beam attenuation coefficient c(λ) is defined as c(λ)=a(λ)+b(λ).

What are various fiber attenuation mechanisms?

There are different optical fiber losses mechanisms: Rayleigh scattering, Absorption, Figure 2.2 Attenuation of the singlemode step index (SM SI) and multimode graded index (MM GI) silica glass fibers as a function of a wavelength.

What is optical Fibre in physics?

An optical fibre is a thin rod of high-quality glass. Very little light is absorbed by the glass. Light getting in at one end undergoes repeated total internal reflection , even when the fibre is bent, and emerges at the other end.

What is numerical aperture of optical fiber?

The Numerical Aperture (NA) of a fiber is defined as the sine of the largest angle an incident ray can have for total internal reflectance in the core. Rays launched outside the angle specified by a fiber’s NA will excite radiation modes of the fiber.

How do you find the numerical aperture of an optical fibre?

Numerical aperture is thus considered as a light gathering capacity of an optical fibre. Numerical Aperture is defined as the Sine of half of the angle of fibre’s light acceptance cone. i.e. NA= Sin θa where θa, is called acceptance cone angle.

What is attenuation and its types?

Attenuation is a reduction of signal strength that occurs through any type of signal like analog or digital. Sometimes it is also called loss & it is a normal signal transmission effect over long distances. The attenuation is low for each unit distance, and then the cable efficiency is more.

How to calculate the attenuation coefficient of an optical fiber?

The attenuation coefficient or attenuation rate α is given by α (dB/km) = A/L. Here L is the distance between points X and Y. The cutback method is often used for measuring the total attenuation of an optical fiber.

What is total attenuation factor?

Total attenuation is the sum of all losses. Optical losses of a fiber are usually expressed in decibels per kilometer (dB/km). For a given fiber, these losses are wavelength-dependent which is shown in the figure below. The value of the attenuation factor depends greatly on the fiber material and the manufacturing tolerances.

How are optical losses of a fiber usually expressed?

Optical losses of a fiber are usually expressed in decibels per kilometer (dB/km). The expression is called the fiber’s attenuation coefficient α and the expression is where P(z) is the optical power at a position z from the origin, P(0) is the power at the origin. For a given fiber,…

How do you find the attenuation of an optical link?

Estimate the Attenuation on the Optical Link. You can now calculate the attenuation for this link. You can arrive at the total attenuation (TA) of an elementary cable section as: TA = n x C + c x J + L x a + M. where: n—number of connectors. C—attenuation for one optical connector (dB) c—number of splices in elementary cable section.