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Optical Switching Basics: Types and Technologies

optical switching wavelength division multiplexing time division multiplexing fiber optic optical communication

Optical switching is the process of controlling the destination of individual optical information signals. This technology allows for high bit rate transmission to be switched between various optical lines.

The core component enabling optical switching is the Optical Switch.

Optical Switching Figure: Optical Switch

Switch control can be achieved through:

  • Purely electronic methods
  • Purely optical methods
  • A hybrid approach combining both optical and electronic techniques

Figure 1 illustrates a typical diagram of optical switching.

Optical Switching Types

There are several types of optical switching, each with its own advantages and applications:

  • Space Division Switching
  • Wavelength Division Switching
  • Time Division Switching
  • Hybrid Switching (combining Space, Wavelength, and Time)

Optical Space Division Switching

Optical Space Division Switching Figure 2: Optical Space Division Switching

Optical Space Division Switching is a straightforward form of optical switching based on a matrix configuration. The figure above illustrates a 3x3 Space Division Switching setup. Key features include:

  • Switching speeds of less than 1 nanosecond
  • Support for very high bandwidth
  • Low insertion loss
  • Transparency to bit rate

Optical Wavelength Division Switching

Optical Wavelength Division Switching Figure 3: Optical Wavelength Division Switching

Optical Wavelength Division Switching connects optical lines based on programming at the wavelength interchanger. As shown in Figure 3, a channel can be routed to the Y channel, the B channel to the X channel, and the C channel to the Z channel.

The wavelength interchanger is critical in this type of switching, making it very suitable for DWDM (Dense Wavelength Division Multiplexing) based networks.

Optical Time Division Switching

Optical Time Division Switching Figure 4: Optical Time Division Switching

Optical Time Division Switching, as depicted in Figure 4, is used in OTDM (Optical Time Division Multiplexing) environments.

The Optical Time Slot Interchanger (TSI) plays a critical role in this type of switching. The TSI rearranges the physical channel positions within the OTDM frame, simplifying routing.

Optical Hybrid Switching

![Optical Hybrid Switching](../../assets/optical-hybrid-switching - if available) Figure 5: Optical Hybrid Switching

Optical Hybrid Switching combines the features of the previously mentioned switching types: time, wavelength, and space.