Different Types of Multiplexing Use In Optical Links

In Optical Links multiplexing can be done by the following techniques

1. TDM
2. SDM
3. WDM

In this guide we shall see both advantages and disadvantages of each techniques

TIME DIVISION MULTIPLEXING (TDM)

• STDM is being use for digital electronic communication since many decades

•  However TDM has serioud limitations due to electro optical Bottle Next so optical TDM is a possibility
• Since TDM is purely a eletronic process using it for Optical signal was not a good idea, so for this purpose we can use OTDM Optical Time Division Multiplexing

• Channel capacity remains same, unlike WDM where each channel capacity may vary.  

SPACE DIVISION MULTIPLEXING

• In SDM multiple optical fibers are used instead of single optical fiber

• Multiplexing may be done on multiple parallel optical fibers

• SDM may be suitable for short distance, using it for long distance can be costly

• SDM suitables with low cost multimode steps index fiber

WAVELENGTH DIVISION MULTIPLEXING

• WDM is the most suitable multiplexing technique for optical fiber as it overcomes the shortcomming of TDM and SDM

• WDM is equivalent of FDM, where traffic from each client is sent on different frequency

• In optical WDM network the term wavelength is used instead of frequency but principle remains same

• Channel capacity can vary, unlike TDM where channel capacity remains same