How do you calculate numerical aperture of graded-index fiber?

∆ = nc − ncl nc ≪ 1 (2) the numerical aperture can be approximated by nc √ 2∆. where a and no are the radius and refractive index at the center of the core, respectively. In the case of a parabolic index fiber (α = 2) the total power that can be launched is one half of that of a step-index fiber with the same ∆ (NA).

What is meant by step index fiber?

For an optical fiber, a step-index profile is a refractive index profile characterized by a uniform refractive index within the core and a sharp decrease in refractive index at the core-cladding interface so that the cladding is of a lower refractive index.

Is numerical aperture is constant in case of step index fiber?

Numerical aperture is constant in case of step index fiber. Explanation: Numerical aperture is a measure of acceptance angle of a fiber. It also gives the light gathering capacity of the fiber. For a single mode fiber, core is of constant refractive index.

What is the value of numerical aperture of an optical fibre?

Typical values of fiber core size ranges from 50 to 100 micrometers and Numerical aperture value ranges from 0.20 to 0.29.

How do you calculate modes in step index fiber?

Examples. In this case the number of modes is: For a typical multi-mode optical fiber with 2a = 50µm, n1 = 1.45, Δ = 0.01, AN = 0.205 and λ = 1.3µm there are approximately 152 modes guided in a parabolic refractive profile and 306 propagable modes for a step-index profile.

What is the difference between step-index and graded index fiber?

step index fiber is fiber type cylindrical waveguide core with inner core has a uniform refractive index of n1 and the core is surrounded by an outer cladding with a uniform refractive index of n2. While the graded index fiber has a core made from many layers of glass and also have the graded index fiber, the …

What is meant by step index?

Definition of step index : an index cut into the fore edge of a book in the form of steps with the edge of each set of leaves preceding an indexed leaf being cut away — compare tab index, thumb index.

What are number of modes in a step index optical Fibre?

This fiber supports four modes, disregarding different polarization states. Various fiber parameters, in particular the numerical aperture and the V number, are originally defined only for step-index fibers, even though effective values are sometimes used for other fiber types.

What is the numerical aperture of an optical Fibre if the angle of acceptance is 16 degree?

Which of the following is described by the concept of numerical aperture in an optical Fibre?

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.

What is the difference between step index and graded index fiber?

Why is numerical aperture important in optical fiber?

The numerical aperture is a measure of the acceptance angle of the fiber. It is very important because it determines how strongly a fiber guides light, and so how resistant it is to bend-induced losses.

What is the numerical aperture of fiber?

The numerical aperture (NA) of the fiber is the sine of that maximum angle of an incident ray with respect to the fiber axis. It can be calculated from the refractive index difference between core and cladding, more precisely with the following relation:

What is the core index of a step index fiber?

A step-index fiber has a core index of refraction of n1 = 1.425. The cut-off angle for light entering the fiber from air is found to be 8.50 o . (a) What is the numerical aperture of the fiber?

What is the index of refraction of a step-index fiber?

A step-index fiber has a core index of refraction of n1 = 1.425. The cut-off angle for light entering the fiber from air is found to be 8.50 o . (a) What is the numerical aperture of the fiber? (b) What is the index of refraction of the cladding of this fiber?

What is the cut-off angle of a step-index fiber?

This cut-off angle is related to the numerical aperture, NA, which is a property of the fiber: n 0 sin θ 0max = ( n12 – n22) 1/2 = NA. A step-index fiber has a core index of refraction of n1 = 1.425.