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INTRODUCTION

Now we are in the twenty first century, the era of ‘Information technology’ there is no doubt that information technology has an exponential growth through the modern telecommunication systems. Particularly, optical fiber communication plays a vital role in the development of high quality and high-speed telecommunication systems. Today, optical fibers are not only used in telecommunication links but also used in the Internet and local area networks (LAN) to achieve high signaling rates.

Here, Our Fiber optics Photo diode module has been uses for study the fiber optic systems. In this module have internal DC source and this module will be supporting external DC voltage also. This module designs for study the Optical Photo Diode voltage vs current (VI) characteristics in Forward Bias, Reverse Bias and Zero Bias. And this module uses for students to get knowledge about optical components.

PREFACE

Principle of Photo Diode

Photodiodes are frequently used photo detectors. They are semiconductor devices which contain a p–n junction, and often an intrinsic (undoped) layer between n and p layers. Devices with an intrinsic layer are called P-I-N or PIN photodiodes. Light absorbed in the depletion region or the intrinsic region generates electron–hole pairs, most of which contribute to a photocurrent. The photocurrent can be quite precisely proportional to the absorbed (or incident) light intensity over a wide range of optical powers.

Operation Modes

Photodiodes can be operated in two very different modes:

Photovoltaic mode: like a solar cell, the illuminated photodiode generates a voltage which can be measured. However, the dependence of this voltage on the light power is nonlinear, and the dynamic range is fairly small. Also, the maximum speed is not achieved.

Photoconductive mode: here, a reverse voltage is applied to the diode (i.e., a voltage in the direction where the diode is not conducting without incident light) and measures the resulting photocurrent. (It may also suffice to keep the applied voltage close to zero.) The dependence of the photocurrent on the light power can be very linear over six or more orders of magnitude of the light power, e.g. in a range from a few nanowatts to tens of milliwatts for a silicon p–i–n photodiode with an active area of a few mm2. The magnitude of the reverse voltage has nearly no influence on the photocurrent and only a weak influence on the (typically small) dark current (obtained without light), but a higher voltage tends to make the response faster and also increases the heating of the device.

Forward Bias Operation

Forward Bias Operation

Reverse Bias Operation


Reverse Bias Operation

Zero Bias Operation

Zero Bias Operation

Model Graph


Model Graph

Optical fiber

The transmission medium in fiber-optic communications systems is an optical fiber. The optical fiber is the transparent flexible filament that guides light from a transmitter to a receiver. An optical information signal entered at the transmitter end of a fiber - optic communications system is delivered to the receiver end by the optical fiber.

Model Diagram for Plastic Fiber cable



Model Diagram for Plastic Fiber cable

Fiber cable Properties



Fiber cable Properties

TECHNICAL SPECIFICATION

Specifications

Photo Diode Type : PIN Photo Diode

Source Wavelength : 660nm to 950 nm

Supply Voltage : +12V DC

Internal DC Source : 0V to +5V

External DC Input : 0V to +5V (Below +5V only)

Photo Diode operation mode : Forward Bias, Reverse Bias and Zero Bias

Photo Diode Interface : Self locking Cap

Supply current : 100 mA (Maximum)

Fiber Cable Type : 1000 Micron Plastic Fiber Cable

Core Refractive Index : 1.492

Cladding Refractive Index : 1.406

Interface connectors : 2mm socket

FEATURES

☞On-board DC source.

☞Input over voltage protection using active components.

☞Supporting External DC voltage at variable range (0V to +5V).

☞Number of test point to study the Photo Diode characteristics.

☞Wider bandwidth link at 660nm to 950 nm.

Internal DC Source

In this module internal DC source produce variable DC voltage at the range of 0V to +5V.

External DC Input

This module was design to supporting external DC voltage at variable range .Here we will give DC voltage in the range of below +5V.

Photo Diode

Here we were used Optical Photo Diode SFH 250V and study this diode characteristics.

Power

In this module will need +12V/500mA DC adapter for power supply. That will be converting +5V in on board.

Front Panel Diagram for Photo Diode Module


Front Panel Diagram for Photo Diode Module

EXPERIMENTAL SECTION

LIST OF EXPERIMENTS

Experiment 1:

To Study the VI Characteristics of Photo Diode at Forward Bias

Experiment 2:

To Study the VI Characteristics of Photo Diode at Reverse Bias

Experiment 3:

To Study the Characteristics of Photo Diode at Zero Bias

APPARATUS REQUIERED OF EXPERIMENTS

Fiber optics Photo diode module : 1 No

Multi meter : 1 No

Patch chord : 4 No’s

Fiber Cable (1 meter) : 1 No

Adapter 12V DC : 1 No

EXPERIMENT - 1: Study the VI Characteristics of Photo Diode at Forward Bias

Aim

To Study the VI Characteristics of Photo Diode

Apparatus Required

Fiber optics Photo diode module - 01

Plastic Fiber cable 1 meter - 01

Multi meter - 01

Adapter +12V/ DC - 01

Patch Chords - 04

Procedure

☞Connect +12V adapter Photo Diode module.

☞Measure the series resistance R.

☞Switch (sw1) ON Photo Diode Module and Multi meter.

☞Connect the multi meter probe, positive to P5 and negative to P6 Ground.

☞Now we get a DC voltage output on multi meter and vary the pot meter min to max range (0V to 5V).

☞Connect P5 and P3 test point, P6 and P4 test point using patch chord.

☞Keep pot meter at minimum position.

☞Now vary the pot meter min to max and note down the reading of Resistor across voltage (Vr) and Diode across voltage (Vd).

☞Tabulate all the readings in below tabular column.

☞And plate voltage vs current curve.

Tabular column

Series Resistance R = 150Ω

SL

NO

Resistor across Voltage ( Vr)

Diode across Voltage

(Vd)

 

Diode current

(Id=Vr/R)

       

Model Graph

Model Graph

The VI characteristic of Optical Photo Diode in forward bias was plated.

EXPERIMENT - 2: Study the VI Characteristics of Photo Diode at Reverse Bias

Aim

To Study the VI Characteristics of Photo Diode at Reverse Bias.

Apparatus Required

Fiber Optics Light Emitting Diode Module - 01

Fiber optics Photo diode module - 01

Plastic Fiber cable 1 meter - 01

Multi meter - 01

Adapter +12V/ DC - 02

Patch Chords - 04

Procedure

☞Connect +12V adapter LED module and Photo Diode module.

☞Switch (sw1) ON the LED Module and Multi meter.

☞Connect P1 and P6 test point, P2 and P7 test point using patch chord in LED module.

☞Vary the DC Source at maximum position.

☞Connect Fiber cable between LED and Photo Diode Module.

☞Now measure the series Resistance R in Photo Diode module.

☞Switch (sw1) ON the Photo Diode Module

☞Connect the multi meter probe, positive to P5 and negative to P6 Ground.

☞Now we get a DC voltage output on multi meter and vary the pot meter min to max range (0V to 5V).

☞Connect P5 and P4 test point, P6 and P3 test point (reversely) using patch chord.

☞Keep pot meter at minimum position.

☞Now vary the pot meter min to max and note down the reading of Resistor across voltage (Vr) and Diode across voltage readings (Vd).

☞Tlate all the readings in below tabular column.

☞And plate voltage vs current curve.

Tabular column

Series Resistance R = 150Ω

SL

NO

Resistor across Voltage

( Vr)

Diode across Voltage

(Vd)

Diode current

(Id=Vr/R)

       

Model Graph



Model Graph

The VI characteristic of Optical Photo Diode in reverse bias was plated.

EXPERIMENT - 3: Study the Characteristics of Photo Diode at Zero Bias

Aim

To Study the Characteristic of Photo Diode at Zero Bias.

Apparatus Required

Fiber Optics Light Emitting Diode Module - 01

Fiber optics Photo diode module - 01

Plastic Fiber cable 1 meter - 01

Multi meter - 01

Adapter +12V/ DC - 02

Patch Chords - 04

Procedure

☞Connect +12V adapter LED module and Photo Diode module.

☞Switch (sw1) ON the LED Module and Multi meter.

☞Connect P1 and P6 test point, P2 and P7 test point using patch chord in LED module.

☞Vary the DC Source at maximum position.

☞Connect Fiber cable between LED and Photo Diode Module.

☞Now measure the series Resistance R in Photo Diode module.

☞Switch (sw1) ON the Photo Diode Module.

☞Connect P3 and P4 test point, P4 and P6 test point using patch chord.

☞Now note down the reading of Resistor across voltage (Vr).

☞Calculate Diode current (Id), Dark current Id = Vr/R

The characteristic of Optical Photo Diode in zero bias was calculated.

TECHNICAL DATA SHEETS

Transmitting LED SFH 250V


Transmitting LED SFH 250V

Plastic Connector Housing

☞Mounting Screw Attached to the Connector

☞Interference Free Transmission from

Light-Tight Housing

☞Transmitter and Receiver can be flexibly positioned

☞No Cross Talk

☞Auto insertable and Wave solderable

☞Supplied in Tubes

Features

☞2.2 mm Aperture holds Standard 1000 Micron Plastic Fiber

☞No Fiber Stripping Required

☞Fast Switching Time

☞Good Linearity

☞Sensitive in visible and near IR Range

☞Molded Microlens for Efficient Coupling

Photo diode Characteristics



Photo diode Characteristics



Photo diode Characteristics