Wavelength-division Multiplexing (WDM) is a method by which several wavelengths of light are carried in a single optical fibre. This allows for a multiplication in capacity, in addition to making it possible to perform bidirectional communication. Several Gbps signals are combined using WDM technique to utilize the vast bandwidth of fibre which is essential to meet the ever growing demand of communication.

Chromatic dispersion results from variation in the propagation delay with wavelength and is depending on the fibre material and dimension. Chromatic dispersion occurs due to the dependence of the velocity of light on the optical frequency when light propagates through the fibre. Different wavelength of light propagates at different velocity in a given medium whose effective index of refraction (neff) varies with respect to the wavelength of light. The first derivative of this delay versus wavelength is the chromatic dispersion value typically specified for fibre.

133-3384 IMG 134-3406 IMG
Benchmark WDM setup consists of individual modules in a vision to provide the users to gain knowledge on the building blocks of WDM and also enhances them to conduct various other experiments separately.
Benchmark WDM & CD teaches the characteristics of the key components used for WDM and CD study. It teaches the concept of wavelength division multiplexing and Chromatic dispersion measurement of single mode fibre. The study of the response of the photo detector at the receiver for the multiplexed wavelength gives a clear understanding of how the lights of two different wavelengths are combined in the fibre. The OFS WDM&CD setup includes a signal generator which gives out two identical signals having a fixed delay between them to facilitate better observation of WDM concept. The knowledge of chromatic dispersion is essential for students while designing high speed fibre optic communication system with dispersion compensation.

List of Items

List of Items

LD Modulator - FOTX-610 - 2 nos
LD Unit (1310nm & 1550nm) FOSM-U900 & FOSM-U1000 - 1 each
Receiver - FORX-500 - 2 nos
LD Driver - FOSM-D600 - 1 no
WDM Coupler - 2 nos
Fixed Attenuators - 1310nm & 1550nm - 1 each
TTL Generator - TTL GENV1.0 1 - 1 no
Single mode Patch cords - 5 nos
2.5 km fibre spool - 1 no



Laser diode unit 1550 nm

  • Type : Fabry Perot
  • Wavelength : 1550nm
  • Output power after 1m single mode fibre : -5 dBm
  • Max Output power : 2mW
  • Max current : 30mA
  • Optical output connector : SC receptacle

Laser diode unit 1310 nm

  • Type : Fabry Perot
  • Wavelength : 1310nm
  • Output power after 1m single mode fibre : -5 dBm
  • Max Output power : 0.9mW
  • Max current : 40mA
  • Optical output connector : SC receptacle

Wavelength selective coupler (WDM)

  • Operating wavelength :1310/1550nm ± (10nm)
  • Insertion loss :1dB typical
  • Ratio :1:1

FOSM - D600: LD driver

  • Possible modes of operation :Forward bias
  • Bias Control :Potentiometer
  • Bias Voltage variation :10V max
  • Power Supply :10V DC
  • Interface Connectors :
    • LD Unit - 5x2 Header
    • Power supply - 5 pin DIN - DIN

FOTX – 610 - LD Modulator

  • TTL Input Data Rate :
    • 400Kbps to 34Mbps NRZ
    • 200Kbps to 17Mbps RZ
  • Power Supply :+ 5V DC
  • Interface Connectors :
    • TTL I/P - BNC
    • LD Unit - 5x2 Header
    • Power supply - 5 pin DIN - DIN

FORX – 500 - Optical Receiver

  • Incident optical wavelength :1550nm
  • Data output :TTL & Direct Amplifier output
  • Modulated optical data input rate :
    • 100Kbps to 34 Mbps for NRZ
    • 100Kbps to 17 Mbps for RZ
  • Power supply :+ 5V DC
  • Interface connectors :
    • Optical Input - ST
    • TTLOutput - BNC
    • Direct Amplifier output - BNC
    • Power supply - 5 pin DIN-DIN


  • Type :Button press
  • Clock speed :564 kHz
  • Patterns :
    • 2 TTL signals without delay
    • 2 TTL signals with 420 ns delay
  • Power supply :+ 5V DC
  • Interface connectors :
    • TTL Output - BNC
    • Power supply - 5 pin DIN-DIN

Fibre patch cords

  • Type :Single Mode Fibre
  • Length :1m, 2.5 km (for CD experiment)
  • Core diameter :8µm
  • NA :0.12
  • Connector :SC/APC

*Specifications subject to change without notice

List of Experiments

 List of Experiments

  • Study of Characteristics of Laser Diode
  • Measurement of Isolation and Insertion loss of WDM coupler
  • Study of WDM concept
  • WDM – End-to-End operation
  • Study of Chromatic Dispersion effect

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