CoarseWavelength Division Multiplexing systemis designed to learn and understand the concept of wavelength multiplexing in a single fiber core. It covers practical aspect of implementing the design by study of optical component parameters and verifying their performance. De multiplexing of wavelengths is demonstratedalong with the recovery of the transmittedsignal.
Channel addition and deletion (dropping) is implemented usingBragggratingandthreeport optical circulator.
This training system is a bench top model capable of demonstrating CWDM with Add-Drop functionality. This system operates in standalone aswell as is PCcontrolmode.

Specifications
Lasers

• 1.25Gbps CWDM Laser Diode Modules at wavelengths of 1510nm, 1530nm, 1550nm, 1570nm
• In built Isolator
• Channel spacing    : 20 nm
• Threshold Current Ith    : 10 mA Typical
• Output power    : @ Ith+ 30 mA - > 0.7 mW @ ~ 58 mA -> 1.4 mW
• Operating voltage    : 1.1V Typical
• Modulation    : Digital modulation with maximum modulation
• frequency 5MHz

Detectors

• 1.5 GHz InGaAs PIN Photo diode Module
• Responsivity    : Typical 0.9 A/W in 9/125μm fiber
• Spectral Range    : 1250nm to 1600nm
• Reverse Voltage    : 30V max CWDM multiplexer and demultiplexer (4 channels)
• CenterWavelength    : 1510nm,1530nm,1550nm,1570nm
•  Channel spacing    : 20nm
•  Passband @ 0.5dB    : ITU+/- 6.5 nm
• Insertion Loss @ MUX / DEMUX Port : <= 2.9 dB
• Adjacent Channel Isolation    : >= 30 dB
• Non Adjacent Channel Isolation    : >= 40 dB
• Max Optical Power    : 300 mW Three Port Circulator
• Polarization IndependentOptical Circulator
• Ports    : 3Nos
• Band    : C+L
• WavelengthRange    : 1525nmto1610nm
• Transmission Direction    : 1->2,2->3
• Channel Isolation    : >40 dB
• Insertion loss    : <= 0.9dB

Fiber Bragg Grating

• CentralWavelength    : 1550±0.5nm
• Bandwidth@3dB    : 0.02–5nm
• SLSR    : >15dB
• Reflectivity    : >90%

Software

• User friendly GUI for monitoring, controlling of CWDM system
• Operating modes like CW mode, VI characteristics mode, Internal & ExternalModulation
• LASER control like Supply ON/OFF, wavelength selection and driving current
• Real time signal levelmonitoring ofPhoto-detector.
• Graphical representation    : XY plot of VI characteristics and Internal Modulation
• COMSettings    : USB2.0
• OperatingSystem    : XP, VISTA, Windows7, Windows8
• Interface    : USBinterface

Experiments
Component characteristics

• Diode laser characterization
• MUX & DEMUX characterization
• Optical circulatorcharacterization
• Bragg Grating characterization

Optical communication system

• 4 Channel CWDM by internal & external modulation
• Add/Drop using Circulator & Bragg Grating