**3.1 Switching technology**

With the growth of network traffic due to continue to meet the insatiable consumer demand for transmission bandwidth, the need for more flexibility and better control over network capacity which drives the need for switching in the optical domain is apparent [29]. **Figure 4** shows a potential photonics switch evolution. The switch fabric circuit is the fundamental building block of the next generation optical network, distributing all network traffic from ingress ports to egress ports and also providing the functionality of sharing the spectrum in the time domain with respect to sub wavelength switching. The performance of switch fabrics is very critical in network applications. Efficiencies must be delivered via the use of switch management which is autonomic and guided by intelligent software algorithms.

*DOI: http://dx.doi.org/10.5772/intechopen.88354 All Optical Signal Processing Technologies in Optical Fiber Communication*

**Figure 4.** *Photonic switch evolution [27].*

As mentioned elastic optical communication are based on the principle that the bandwidth of fiber can be partitioned dynamically into adaptable size spectrum slots. The size and state of each space are generally customized to the prerequisites of a particular (group of) channel(s) in order to achieve effective network-wide transport. This fine slicing and shaping of passbands is achievable with spectrum selective switching (SSS) devices feature a fine spectrum granularity that facilitates the employment of customizable filters with variable bandwidth, e.g. from 10 GHz to 5 THz in 1-GHz increments, and attenuation, e.g. programmable from 4 dB to 30 dB in 1-dB steps [30].

A few optical switch technologies are shown in **Table 1** that can be used in elastic networks. The combination of gridless spectrum switching and rapid time switching devices advances empowers the provisioning of a wide range of optical bandwidth granularities [6]; however, they do not have a large port-count, which makes them incompatible for connecting devices in an elastic optical node. Fast switching are more easily achieved with semiconductor optical amplifiers (SOA) or electrooptic materials such as LiNbO3 or PLZT. Large port-counts are usually implemented with 3D-MEMS [38] or direct beam-steering devices [39] (achieves lower insertion


#### **Table 1.**

*Optical switch technologies.*

loss than 3D-MEMS [40]), they have a slower response than fast switching devices, on the order of 10 ms.
