Optical fiber

1. NAME : K . ABHINAY
CLASS : CSM-C
ROLL NO : 227Y1A66D1
FACULTY : DR K . CHAITHANYA KUMAR

2. AIM OF THE EXPERIMENT
To determine the numerical aperture of an
optical fiber.

3. ⦿Numerical aperture of an optical fibre is
defined as the light gathering ability of
the fibre.
⦿Numerical aperture also refers to the
maximum angle at which the light
incident on the fibre end is totally
internally reflected and is properly
transmitted along the fibre .

4. ⦿An optical fiber (or optical fibre) is a
flexible, transparent fiber made of glass
(silica) or plastic, slightly thicker than a
human hair.
⦿ It functions as a waveguide, or “light
pipe”to transmit light between the two
ends of the fiber.

5. IT WORKS ON THE
PRINCIPLE OF TOTAL
INTERNAL
REFLECTION.

6. ⦿Low Transmission Loss and Wide
Bandwidth
⦿Immunity and Interference
⦿Small Size and Weights
⦿Signal Security
⦿Electrical Isolation
⦿Abundant Raw Material
⦿Less Expensive

7. ⦿An optical fibre cable
⦿Optical fibre trainer board
⦿Screen
⦿connecting wires

8. ⦿Fiber Optics Trainer
Model is designed
to learn the basics
of fiber Optics.
⦿ A large number of
experiments.

9. ⦿Make all the connections .
⦿Connect one end of the optical fibre cable to
the optical fibre trainer and other end to the
numerical aperture jig.
⦿Hold the white screen with four concentric
circles (10, 15, 20 and 25 mm diameter)
vertically at a suitable distance to make the
red spot emitted from the optical fibre
coincide with the 10 cm circle. Note that the
circumference of the spot (outermost) must
coincide with the circle.

10. ⦿Record L, the distance of the screen from the
fibre end and note the diameter (W) of the
spot.
⦿Compute the numerical aperture (NA) of the
optical fibre by using the formula
⦿NA = Sinθ=W/(4L2+W2)1/2,
⦿ where θ is called as the acceptance angle
is the maximum angle of incidence at the
input end of the optical fibre so that he
optical ray can just propagate within the
optical fibre.
⦿Tabulate the reading and repeat the
experiment for 15 mm, 20 mm and 25 mm
diameter too.

11. S.No LENGTH(mm
)
DIAMETER
OF THE
SPOT(mm)
NUMERICAL
APERTUER(
NA)
ACCEPTANC
E ANGLE(
DEGREE)
1 9 10 0.4 23.5
2 14 15 0.4 23.5
3 19 20 0.4 23.5
4 24 25 0.4 23.5

12. ⦿NUMERICAL APERTURE
OF OPTICAL FIBRE IS
0.4MM.