**3. SOA-based switching fabric**

4 Optical Amplifier

(Mack et al., 2008). The synchronizer is composed by *NSYN* stages. There are one 1 × 2 splitter, one 2 × 1 coupler, two SOAs, two optical bandpass filter(OBF) and one FDL in each stage. SOAs were used as the gates to select the required delay and compensate for losses. In order to suppress accumulated amplified spontaneous emission, Optical Bandpass Filters was placed

Fig. 3. Fiber based synchronizer with SOA gates and Optical Bandpass Filter (OBF). Δ is the

In packet switching networks, tuneable wavelength converters can be used to resolve packet contention and overcome the optical buffering problem. An example of SOA-based Wavelength Converter is illustrated in Fig. 4. It is referred to as Delayed Interference Signal WCs (DISCs) and has been proposed in (Sakaguchi et al., 2007). DISC employs nonlinear effect in SOA and utilizes an SOA and an OBF placed at the amplifier output. It can be constructed by using commercially available fiber-pigtailed components. It has a simple

**SOA**

Fig. 4. Realization of an all-optical wavelength converter by using a Delayed-Interference

**control signals**

OBF

OBF **Optical BandPass Filter**

**S P L I T T E R**

OBF **Optical BandPass Filter Fiber Delay Lines**

**SOA**

OBF

NSYN-thStage

> **NSYN** Δ

OBF

**Probe Signal**

DISC

**C O U P L E R**

Synchronizer

**control signals**

**SOA**

inside each synchronizations stage.

1-stStage

**SOA**

OBF

OBF

**control signals**

**SOA**

**S P L I T T E R**

> **Semiconductor Optical Amplifier (SOA)**

**Semiconductor Optical Amplifier (SOA)**

**Probe Signal**

**C O U P L E R**

**C O U P L E R**

Δ

delay introduced by the fiber delay line of the 1*st* stage.

**2.2 Realization of SOA-based Wavelength Converters**

configuration and allows photonic integration.

**Pump Signal**

> **control signals**

Signal Wavelength Converter (DISC).

Laser

Switching fabric in Future Optical Packet Switches require high-speed optical switches (or gates). That can either be optically or electrically controlled. Such optical switches can be constructed using SOAs due to their high switching rate. The simplest method to control an SOA gate is by turning the device current on or off. The great advantage of SOA gates is that they can be integrated to form gate array. Next we illustrate SOA-based Single-Stage and Multi-Stage switching in Sections 3.1 and 3.2 respectively.
