**4.1.1 Simulation of AND gate based on turbo-switch**

A simulation was carried out to evaluate the 160 Gb/s all-optical wavelength conversion using a turbo-switch and a delayed interferometer (DI). The setup is shown in Fig. 8(a), where a polarization maintaining fiber (PMF) and a polarizer are used to form a DI (Reid et

Fig. 8. All optical wavelength conversion using a turbo-switch. (a) Setup; (b) 160 Gb/s simulation results. The blue/ red curves are the TE/TM polarized components. Note that polarization controllers are not plotted for simplicity.

Consequently, there is an optimum optical power level that could mitigate the pattern effect at a specific bit-rate. For instance, in this case, the optimum power to SOA2 should be -11

On the contrary, the simulated modulation curves in Fig. 7(a) and 7(c) both experience a worse trend (constantly lower or higher) under a sequence of consecutive marks (ones) or spaces (zeros). This implies that, the unsaturated (-26 dBm), saturated (-11 dBm) and oversaturated (14 dBm) input power level to SOA2 has an important impact on the overall performance of turbo-switch. For instance, in the case of the modulated CW power of -26 dBm, the SOA2 cannot be saturated, and the overall recovery time is not shortened, turbo-

The turbo-switches are supposed to be applied in the all-optical signal processing in order to enhance the operation speed. The turbo-switches have been employed as the all-optical AND gate (wavelength conversion) and XOR gate, whose operation speeds have been increased up to 160 Gb/s and 85 Gb/s respectively. In this section, we will demonstrate the details of the high-speed operation of the turbo-switches, from both theoretical and experimental aspects.

The simulation results of the AND gate at 160 Gb/s will be given in Section 4.1.1, while the corresponding experimental results (i.e., wavelength conversion) at 170 Gb/s will be

A simulation was carried out to evaluate the 160 Gb/s all-optical wavelength conversion using a turbo-switch and a delayed interferometer (DI). The setup is shown in Fig. 8(a), where a polarization maintaining fiber (PMF) and a polarizer are used to form a DI (Reid et

Fig. 8. All optical wavelength conversion using a turbo-switch. (a) Setup; (b) 160 Gb/s simulation results. The blue/ red curves are the TE/TM polarized components. Note that

dBm, as shown in Fig. 7(b), where the pattern effect is mitigated.

switch behaviors similarly to a single SOA, as shown in Fig. 7(a).

**4. Applications of turbo-switch** 

**4.1 High-speed AND gate beyond 160 Gb/s** 

**4.1.1 Simulation of AND gate based on turbo-switch** 

polarization controllers are not plotted for simplicity.

presented in Section 4.1.2.

al., 2008). The DI utilizes the differential cross phase modulation (XPM) effect of the SOA to achieve the polarity-maintaining wavelength conversion. The PMF is used to introduce a delay between the TE / TM components of the probe, thus introducing a differential phase shift between the two orthogonal components. On the other hand, the polarizer acts as an interfering device to extract phase difference between the two components, which is the wavelength-converted output.

Fig. 8(b) presents the 160 Gb/s wavelength-converted output trace and the corresponding eye diagram. The average powers of the CW and the pump are 10 and 3 dBm respectively, while the wavelengths of the CW and pump are 1560 and 1550 nm respectively. The input PRBS data has a length of 27-1. The PMF gives a differential delay of 2 ps. It is shown that the turbo-switch configuration expedites the recovery of the intensity and phase, which helps to mitigate the patterning of the output. The clearly opening eye diagram of the output shows the feasibility of the wavelength conversion at 160 Gb/s. More specifically, the well-known Q factor, defined for instance in (Agrawal, 2002), for the output signal is 6.8, which corresponds to the bit error rate (BER) of 6.9×10-12.
