**2.3. Summary**

interference output (port #B). An isolator is placed at ports #I, #D and #A to protect all laser

**Figure 15** shows the data input signals (1) injected into the arms #A and #D of the MZI-SOA, each with 2 dBm mean power, and the corresponding XOR gate output (2), at 10 Gbps at port #J, in a co-propagating scheme. In this experimental scenario, the results are in conformity with the truth table of an XOR gate: the output presents a logical zero (0) if both the operands have

**Figure 15.** Optical sequences at MZI-SOA input ports #D and #A (first two signals from top) and resulting XOR output

0 0.5 1 1.5 2 2.5 3 3.5 4

Input power (dBm)

**Figure 16.** Experimental measurements of the ER of the output signal, as a function of the input power for co-propaga-

at port #J (bottom sequence). Horizontal scale: 500 ps/div. Vertical scale is arbitrary.

9.5

tion (+ sign) and counter-propagation (× sign) schemes.

10

10.5

Extinction Ratio (dB)

11

11.5

12

sources from back propagation signals.

178 Optical Interferometry

*2.2.2. Experimental results and discussion*

identical value and a logical one (1) otherwise.

Having in mind next generation optical networks, which are meant to be as flexible and transparent as possible, this section has characterized the static properties and the operating conditions of the MZI-SOA working as an optical gate, which results will be useful for the following section, dealing with phase modulation and other advanced modulation format conversion techniques.
