EXPERIMENT NO. 1

AIM: - Setting up a fiber optic analog link.

APPARATUS REQUIRED: - Fiber optic Trainer kit, function generator, fiber cable, C.R.O., patch cords.

THEORY:- Fiber optic links can be used for transmission of digital as well as analog signals. Basically, a fiber optic link contains three main elements, a transmitter, an optical fiber& a receiver. The transmitter module takes the input signal in electrical form& then transforms it into optical (light) energy containing the same information. The optical fiber is the medium, which carries this energy to the receiver. At the receiver, light is converted back into electrical form with the same pattern as originally fed to the transmitter.

PROCEDURE: -Keep all the switch faults in off position.Make connections as shown in fig. While connecting this ensures that the power supply is off.Connect function generator to trainer kit.Keep the jumpers JP2 &JP3 on FCL-03 as shown in fig. Switch on the power supply.Connect the 2 KHz, 2Vpp Signal from FG. As a constant signal to the IN post of the Analog Buffer on FCL-03. Connect the output of Analog Buffer post OUT to post TX IN.Slightly unscrew the cap of LED SFH756V. Do not remove the cap from the connector. Once the cap is loosened, insert the fiber into the cap. Now tighten the cap by screwing it back.Slightly unscrew the cap of RX2 Photo DiodeSFH250V. Do not remove the cap from the connector. Once the cap is loosened, insert the fiber into the cap. Now tighten the cap by screwing it back.Observe the output signal from the detector at ANALOG OUT post on Oscilloscope by adjusting Optical power control Pot 3 in clockwise direction and you should get the reproduction of the original transmitted signal. 10. To measure the analog band width of the link, keep the same connection and vary the frequency of the input signal from 100 Hz onwards. Measure the amplitude of the received signal for each

frequency reading.Plot a graph of Gain/Frequency. Measure the frequency range for which the response is flat.

PRECAUTIONS: -1. Slightly unscrew the cap of LED. Do not remove the cap from the connector. Once the cap is loosened, insert the fiber into the cap. Now tighten the cap by screwing it back. 2. You have to prepare each end of the fiber cable very carefully so it transmits light effectively. 3. Cut of the ends of the cable with a single-edge razor blade or sharp knife. Try to obtain a precise 90 degree angle.4. Permissible ambient temperature range for CRO during operation is 0- 40(c the Ventilation holes should not be covered.

EXPERIMENTAL SET UP: -

RESULT:-

CONCLUSION:-

EXPERIMENT RELATED QUESTION:-

1. Give the name of fabrication method of optical fiber?

2. What are the applications of optical fiber?

3. What are step index fiber & Graded index fiber?

4. What are single mode fiber &Multimode fiber?