PICWave

An SOA-based active 2R optical regenerator

Simulation with PICWave software

One of PICWave's strengths is its ability to combine passive and active components. This optical regenerator consists of a large passive optical circuit totalling over 10,000μm of waveguides plus two semiconductor optical amplifiers (SOA).

Simulation of an active 2R regenerator in PICWAVE:
circuit designed in the PICWave layout, resulting eye diagram calculated by PICWave

The regenerator is shown schematically above, consisting of a Mach-Zehnder interferometer with an SOA in each arm. Initially a steady state signal is injected in to the device at B and passes through both arms of the MZI then recombines on the right. When a data signal is present at A, this upsets one of the SOAs causing destructive interference when the B signal recombines, turning off the output. By this means we can regenerate the signal on/off levels, amplify the signal and convert the signal to another wavelength.

The regenerator was simulated with PICWave using an NRZ pseudo-random input bit pattern with an on/off ratio of 5:1 and a rise time of 100ns. To the right is shown eye diagrams of both the input and output signals. Notice the much higher on/off ratio of the regenerated signal and also the 20x amplification. Note however how the SOAs have added significant noise to the output. PICWave includes an extensive model for noise sources present in semiconductor devices, modelling carrier fluctuations, phase noise and intensity noise.