EXPERIMENT NO. 1 (EDWDM KIT)

1. AIM : - To study the

(1) Laser characterization as Power versus Wavelength. (2) FBT (fused biconical tapers) Coupler constructors (3) Isolators: measurements of input and output power. (4) Circulator: measurement of input power and output powers at 2nd and 3rd port. (5)Brag Grating: power at input and output ports in Forward direction and in Backward direction.

2. APPARATUS:- EDWDM KIT ,Fiber optics wire

3. Observations:- (1) Wavelength versus power characterization: Here we are taking different Laser light sources of different wavelength and observing the corresponding power. Assuming no attenuation here.

Wavelength(λ) (nm)

Power(dB) Wavelength (nm)

Power(dB) Wavelength (nm)

Power(dB)

1550.100 -0.33 1549.32 0.26 1306 -0.59

1550.12 -0.31 1549.48 0.27 1306.02 -0.61

1550.14 -0.30 1549.65 0.28 1306.04 -0.62

1550.16 -0.29 1549.72 0.29 1306.05 -0.63

1550.27 -0.28 1549.86 0.30 1306.07 -0.64

(2) FBT coupler 50/50: Couplers are used to couple two signals. Here we are using 4 port FBT (fiber biconical taper) coupler where the input is given at port1 and the coupled power is observed at port4 and the forward power is observed at port3. As this is a50/50 coupler so it will divide the input power in two equal half means the ratio at port3 and port4will be 1.

Wavelength(λ)(nm) P1 (dB) P2(dB) P3(dB) P4(dB)

1549.32 .64 - -2.97 -2.68

1549.48 .64 - -2.75 -2.63

1549.65 .65 - -2.73 -2.62

1549.72 .66 - -2.7 -2.58

1549.86 .68 - 2.69 2.55

1549.98 .69 - 2.67 2.53

(3) FBT coupler 20/80: Here the output power at port4 will be four times of output power at port3. Power at port 4 is coupled power.

Wavelength(λ)(nm) P1 (dB) P2(dB) P3(dB) P4(dB)

1549.32 .36 - -1.56 -7.81

1549.48 .38 - -2.7 -7.56

1549.65 .42 - -1.58 -7.78

1549.75 .43 - -1.38 -7.58

1549.96 .44 - -1.55 -7.76

1549.98 .45 - -1.52 -7.76

(4) Wavelength division multiplexing (WDM): Here the wavelength λ1=1307.4 is given to port1 and the λ2 is given at port2 and these are passed through a WDM coupler which multiplexes both waves and the corresponding outputs are observed at port3 and port4 .now these two ports are further connected to other WDM coupler which couples the power at port3 and port4. And the output is observed at the port5 and port6 of second coupler.

Wavelength(nm) P1(dB) P2(dB) P3(dB) P4(dB) P5(dB) P6(dB)

Only port 3 is connected

1307.4 -1.4 - -29.8 -1.49 -49.28 -30.74

1550.0 - -1.56 -32.74 -.68 -29.44 -46.48

1307.4 + 1550.0 -1.96 - -27.86 1.95 -29.37 -30.58

Only port 4 is connected

1307.4 -1.4 - -29.8 -1.49 -29.87 -1.97

1550.0 - -1.56 -32.74 -.68 -1.22 -36.86

1307.4 + 1550.0 -1.96 - -27.86 1.95 -1.18 -1.95

(5) Isolators: Isolators allows the power transmission in only one direction from port1 to port2.but the reverse transmission of power is not possible.

So here we gave a input power at port1 and corresponding output at port2 is observed. Which is in the range of input. But if we give input at port2and observe output at port1then the output is reduced. Means transmission in only one direction is possible here.

Wavelength(nm) P1 (input) dB P2(output) dB P2(input) dB P1(output) dB

1307.4 -1.14 -3.20 -1.13 -10.73

1306.0 -.41 -2.79 -.41 -10.03

(6)Brag Grating: As in Brag Grating a particular wavelength is eliminated in a spectra.so here we are measuring the output of port2 corresponding to the input of port1 and between these two port the brag grating is inserted so the wavelength is removed .so why the output is lesser than the applied input.

Wavelength(nm) P1 (input) dB P2(output) dB P2(input) dB P1(output) dB

1307.4 -1.14 -1.19 -1.14 -1.15

1306.0 -.41 -.69 -.41 -.64

(7) Circulators: In circulators at one time we obtain output only at one port which is successive port to the input port. Here when the input is applied is only port1 then the output is observed at port2 and at port3 the power is very low or say it should be negligible compare to the input power .same as the other two readings are taken.

Wavelength(nm) P1 dB P2 dB P3 dB

1307.00 Input = -1.14 Output = -4.48 Output = -64.44

1307.00 Output = -16.91 Input = -1.14 Output = -5.86

1307.00 Output = -- Output = -19.72 Input = 1.14

4. Result:- From the observation taken above we have justified the different characteristic of

the different fiber optic component and some variations are there because of the different type of losses like bend loss, joint loss in the fiber and attenuation and the heating of the laser source to achieve a stable output and losses at the connecting point of different points.

EXPERIMENT NO.2 (EDCOM) 1.OBJECTIVE:

1. To study LED sources and LASER sources characterization.

2. To study attenuation for LED sources and LASER sources.

2.APPARATUS:

1. EDCOM kit

2. Fiber reel (Fiber type: Graded Index Multimode fiber, Size: 62.5/125/250 m)

3. ST connector

4. Patch cords

3.THEORY:

EDCOM Kit: The equipment is designed to demonstrate the principles and effects

of both attenuation and dispersion phenomena in optical fiber communication

systems. Another requirement is that the dispersion of the optical fiber link must

be sufficiently high (resulting in a low system bandwidth) to be compatible with

laboratory equipment (i.e. a 50MHz oscilloscope). Consequently, a graded index

optical fiber with non-ideal refractive index profile was chosen for the fiber link.

➀Modulation ON/OFF ➄Drive Current Displays ➈Received Power Displa

➁Sine/Square Select ➅LED Output ➉Receiver Signal BNC

➂Sine Frequency Control ➆Laser Output

➃DC Bias Controls ➇Photo receiver DETAILS OF EQUIPMENTS:

The OPTOSCI Fiber Optic Communications Educator Kit consists of the following

hardware elements:

• An 850nm, ST receptacled, light emitting diode (LED) transmitter with

adjustable drive current and modulation signal input. The drive current (in mA) is

displayed on an integral panel meter. The rms spectral line width of the source is

30nm.

(The maximum drive current and maximum modulation amplitude which can be

applied to the LED is limited internally.)

• A 785nm, ST receptacled, laser diode transmitter with adjustable drive current

and modulation signal input. The drive current (in mA) is displayed on an integral

panel meter. The rms spectral line width of the laser at its operational current is

approximately 1nm. (The maximum drive current and maximum modulation

amplitude which can be applied to the Laser Diode is limited internally.)

• Two reels (approximately 1 km and 2 km in length) of graded index 62.5µm core

diameter silica multimode fiber with ST connectorised output leads. The

numerical aperture (NA) of the fiber is 0.275 and its effective group refractive

index is 1.497.

• 1m ST connectorised graded index 62.5µm core diameter silica multimode fibre

patch cord (a spare patch cord is also supplied).

• One ST receptacled Si pin photodiode receiver with a 50Ω BNC output port. The

detected optical power (in µW) is displayed on an integral panel meter.

• A waveform generator which can be switched between a 4MHz square wave

pulse generator with a fast rise time, and a variable frequency (1 to 28 MHz) sine

wave generator. The waveform generator has a separate enable/disable switch

and the output signal is available via a 50Ω BNC output port. The output signal for

both waveforms is 10V pk-pk maximum.

• One bulkhead ST connector.

• An integrated power supply (on/off switch at the rear of the unit) and all

required electrical interconnects, 50Ω BNC cables and a BNC T-piece connector.

• A two channel laboratory oscilloscope with a minimum bandwidth of 50MHz

and a time base which can display at least 5ns/div. This is the minimum

requirement to perform the rise time measurements.

4. PROCEDURE AND OBSERVATION: Comparison of LED and Laser Diode Characteristics:

1. Optical Output Power against Drive Current:

1. Connect the 1m fiber patch cord between the LED (note the number on

the end of the patch cord) and the Photo receiver, record the detected

optical power at the receiver as a function of the drive current

2. Repeat the power out versus drive current measurements for the Laser

Diode source (remembering to follow the safety precautions).

2. Optical Fiber Connector Loss:

In this experiment the optical loss at a bulkhead ST connector is

determined. The connector loss is determined following transmission

through fiber reel #1 to establish an equilibrium mode distribution in the

fiber.

1. Connect the LED transmitter to the receiver using fiber reel #1 and record

the detected power. Now determine the optical loss resulting from the use

of a fiber connector in the system by inserting the bulkhead ST fiber

connector and 1mpatchcord between the end of fiber reel #1 and the

receiver.

2. Repeat the measurement of connector loss using the Laser Diode source.

3. Attenuation of the Optical Signal over the Link Length:

Check the launch power into the 1m patch cord for the LED and Laser Diode

sources. Now measure the total attenuation of the launched signal from

each optical transmitter after propagation through fiber reel #1 (remember

to note the number on the end of the patch cord connected to the

transmitter). Repeat the measurements for fiber reel#2.

(1) For LED source:-

S.NO. Current (mA) Power( W)with fiber reel #1

Power( W)with fiber reel #1 & ST connector

Power( W)with fiber reel #2 & ST connector

1. 10.0 4 4 2 2. 20.0 7 7 4

3. 30.0 10 10 5 4. 40.0 13 12 6

5. 50.0 15 15 8 6. 60.0 18 18 9

7. 70.0 20 20 10 8. 80.0 23 22 11 9. 90.0 25 24 12

10. 97.0 26 25 13

S.NO. Current (mA) Power( W)with fiber reel #1

Power( W)with fiber reel #1 & ST connector

Power( W)with fiber reel #2 & ST connector

1. 1.0 1 1 1 2. 7.0 1 1 1

3. 13.0 1 1 1 4. 13.5 2 2 1

5. 14.6 3 3 2 6. 15.0 7 7 3 7. 15.5 16 16 6

8. 16.0 24 24 9 9. 16.5 33 32 12

10. 17.0 41 40 15 11. 17.5 49 47 18 12. 18.0 56 56 21

13. 18.5 65 64 24 14. 19.0 72 71 27

15. 19.5 80 80 30 16. 20.0 89 87 33

17. 20.6 98 97 36

2. For LASER source.

4. Bandwidth Measurements:

Digitally modulate the LED transmitter and LASER transmitter (using the

square wave) and, from appropriate measurements of pulse rise times

(10% to 90%) on the oscilloscope, determine bandwidth of LED and LASER

source using this formula.

Division (Rise Time)

Division (Fall Time)

Time/Div ( s)

Magnification Rise Time( s)

Fall Time( s)

LED source(60.0 mA,18 W)

4 3 0.5 10 0.2 0.15

LASER source(15.0 mA,104 W)

5 4 0.5 10 0.25 0.2

BW =0.48/τF =0.187/τR

τR = 0.39 τF

τR = Rise Time(10- 90%)

τF = Fall time(10- 90%)

bandwidth BW (LED) = .48/.15u = 3.2 MHz bandwidth BW (laser) = .48 /.2u = 2.4 MHz

RESULT: Green- for LASER source, Blue- for LED source

X-axis- Current (mA), Y-axis- Power ( W)

1. Power ( W) with fiber reel #1 vs Current(mA) for LED source & LASER source.

2. Power ( W) with fiber reel #1 & ST connector vs Current (mA) for LED source &

LASER source.

3. Power ( W) with fiber reel #2 & ST connector vs Current (mA) for LED source

& LASER source.

EXPERIMENT NO.3 (EDLASE KIT)

1.AIM :- 1. Output power at receiver when input is pump power from a laser source .

2. band limiting filter construction

3. measurement of feedback coupler(80-20%) input and output power

4. Measurement of feedback coupler (60-40%) input and output power.

5. Variable attenuator construction

2. APPARATUS: EDLASE kit, ST connectors, patch chords.

3. OBSERVATION TABLE:-

1. Pump power VS out power:- when the input pump power from the input laser

source is switched on then the corresponding output power at output receiver is noted

down. Pump power(mw) Power(uw) Pump power(mw) Power(uw)

2 0 1 0

4 2 3 0

6 22 40 1160

8 100 50 1160

10 237 60 1160

12 411 70 1160

14 601

16 800

18 998

20 1160

30 1160

2. Band limiting filter:- Laser pump power input is internally connected to the band

limiting filter’s input and the output of the filter is connected to output of photo- receiver.

is given in EDFA output and Output is given at photo receiver side.

Pump power(mw) Photo receiver(uw)

0 3

10 3

15 4

25 5

36 6

(3)Feedback Coupler (80-20%):- The laser Input is connected to EDFA input and this input

is divided in two coupled Output having ratio 4:1.each of the coupled output is connected to the photo receiver to observe the power at each node.

Pump power Input(mw) 80%(uw) 20% output(uw)

0 4 2

0

200

400

600

800

1000

1200

1400

0 10 20 30 40 50 60 70 80

ou

tpu

t p

ow

er(u

W)

pump power(mW)

output power(uW)

45 6

53 7

2 4 2

5 6 2

6 9 3

7 15 4

8 25 7

9 40 10

12 93 24

15 153 40

18 216 57

19 237 62

20 259 68

25 368 97

30 496 128

35 621 162

40 742 192

50 974 251

60 1160 314

(4) Feedback coupler (60-40%):- The laser Input is connected to EDFA input and this input is divided in two coupled Output having ratio 3:2.each of the coupled output is connected to the photo receiver to observe the power at each node.

Input(mw) 60%(uw) 40%output(uw)

0 1 1

5 3 2 10 43 29

15 119 82

20 199 139

25 285 196 30 376 260

35 478 328 40 572 390

45 657 453

50 749 515 55 842 578

60 931 640 65 1022 703

72.8 1160 801

(5) Variable attenuator: - laser pump power Input is connected to the input of the EDFA(60%-

40% feedback coupler ) and output of this EDFA is connected to the input of the variable ATTENUATOR and its Output is connected to photo receiver side. Then the effect of the attenuation is observed for a given input power.

INPUT POWER IS FIXED AT 40Mw. ATTENATION (DB) OUTPUT POWER 0 1060

1 1056

4 1058

6 994

7 917

8 819

9 746

10 718

11 655

12 599

13 500

14 381

15 248

16 169

17 113

18 56

19 26

20 9

20.9 3

5. RESULT: - From above observations, we can characterize different types of fiber

optics components and effect of them on the input laser power BUT In these

observations, there are some variations due to bend loss, joint loss etc.

We have seen the effect of attenuation on output power as it reduces when attenuation

is increased.

EXPERIMENT NO.4 (EDAMP KIT) 1. OBJECT:

1. TO MEASURE THE OUTPUT POWER OF THE EDFA (erbium doped fiber amplifier),

when using a 1550nm wavelength as input power source.

2. To measure the output power when using a 4.4KM long optical fiber and observe

the attenuation effect on the length of fiber.

2. APPRATUS: 1. EDAMP kit 2. Fiber reel (Fiber type single mode fiber, Size:9/125/1250um ,cut- off wavelength 1250-

1250nm,fiber length 4,4km) 3. ST connector 4. Patch cords

DETAILS OF EQUIPMENTS: The OPTOSCI EDFA laboratory educator kit consists of the following hardware elements:

• A connectorised erbium doped fiber amplifier lumped by a 980nm laser diode to provide small Signal gains in excess of 25dB. The amplifier contains two optical isolators and has angle Polished connectors to limit positive feedback and completely suppress oscillation (i.e. laser Action).

• A 1550nm DFB laser source to provide the input signals. The source has been specially Designed to provide signal levels in a range from approximately -40dBm up to 0dBm (1mW) Without degradation of its coherence properties i.e. its line width). This is required to enable the Investigation of small and large signal gain.

• A custom designed photodiode detection system for measuring the input signal levels over a large (50dB) dynamic range. The unit also allows the measurement of the amplified AC signal power super imposed on a high quasi DC level of ASE.

• Fixed 15dB In-line optical attenuator

• All of the necessary fiber cable patch cords to enable connection between the various units of the system

.• A two channel laboratory oscilloscope with a minimum bandwidth of 20MHz.

3. OBSERVATION:- (1) using only 1m patch cord and no input power only pump power:-

Pump power (mW) EDFA OUTPUT(db) Pump power(mw) EDFA output (db)

0 -143.7 10 -5.5

.5 -48.4 11 -3.9

1 -37.4 12 -2.9

2 -32.4 13 -1.9

3 -28.3 15 -.4

4 -24.6 15.8 0.00

5 -20.3 20 1.8

6 -15.8 25 2.0

7 -12.1 72.3 2.0

8 -9.2

9 -7

(2) using a 4.4km fiber reel ,pump power and without input power:-

Pump power (mW) EDFA OUTPUT(db) Pump power(mw) EDFA output (db)

.1 -143.6 5 -21.3

.5 -50.9 6 -16.7

.8 -40.8 7 -13.3

1 -39.4 8 -10.4

2 -33.5 9 -8

3 -29.9 10 -6.4

4 -25.9

(3) using a fiber reel(4.4km) and input power of 1550nm input source:-

Pump power (mW) EDFA OUTPUT(db)

1 -18.2

2 -11.2

3 -6.1

4 -3.0

5 -1

6 0.5

8 2

72.3 2

4. RESULT:- We have seen the output of EDFA and observed that the output is

amplified. Here the EDFA used use a 25dB gain as the input power is increased around 2.5 to 3 times more than the input power, pump power also seen the effect of attenuation as the reduced power is observed at the fiber reel end is very less than the input pump power.

EXPERIMENT NO. 5 (LIGHT RUNNER)

1.AIM :- To study the length dependence of attenuation of in the given optical fiber at different

wavelengths.

2.Apparatus:- Light runner kit (c-band lasers,850nm lasers, Inga As photo detectors, silicon photo

detector(PD5)), fiber spools of length 1km,2km,3km.

Light runner:-

3.Theory and formula:- If P1 represent the input power and P2 represent the output power and the

length of fiber is L, then attenuation in the fiber is given by, A = -10log(P2/P1) db And the attenuation coefficient is given as α (db/km) = -(10/L)log(P2/P1) Here, each fiber connector has 0.5db loss.

4.Observations:- To perform this experiment firstly we switch on the light runner kit. We select the

experiment LOSS from drop down menu .now connect the 850nm laser source with the patch cord to the fiber spool and through one another patch cord connect the spool to the PD-5 connection .through a BNC connecter connect the PD-5 to the channel-1 to see the waveform and corresponding data on the screen panel.

set some parameters for this 850nm laser source that is (a)frequency = 50 khz (b) duty cycle =20% (c) laser power = 60%

1. Now click on the ‘start’ button and observe the output power and ‘stop’. 2. Do the same for other wavelengths.

Length of fiber(km)

Wave-length(nm)

Input power (P1 uw)

Output power (P2 uw)

Attenuation A (db)

Attenuation coefficient α (db/km)

Number of connectors

when are not A (db)

Connectors Included α (db/km)

1 850 408 134 4.835 4.835 2 3.835 3.835

1550 37 19 2.894 2.894 2 1.894 1.894

2 850 408 126 5.103 2.55 2 4.103 2.0515

1550 37 17 3.3775 1.68875 2 2.3775 1.18875

3 850 408 19 13.319 4.4396 2 12.319 4.106

1550 37 10 5.682 1.894 2 4.682 1.56

4 850 408 18 13.5538 3.38845 3 12.0538 3.01345

1550 37 8 6.6511 1.62775 3 5.1511 1.2877

5 850 408 6 18.325 3.665 3 16.825 3.365

1550 37 6 7.901 1.5802 3 6.401 1.28

6 850 408 3 21.3354 3.5559 4 19.3354 3.2225

1550 37 2 12.6717 2.11 4 10.6717 1.7786

5.Result:- We see as the length of the fiber increases the attenuation increases .