Rofea’ modulator bias controller is specially designed for Mach- Zehnder modulators to ensure a stable operation state in various operating environments. Based on its fully digitized signal processing method, the controller can provide ultra stable performance.
The controller injects a low frequency, low amplitude dither signal together with bias voltage into the modulator. It keeps reading the output from the modulator and determines the condition of the bias voltage and the related error. A new bias voltage will be applied afterwords according to the previous measurement. In this way, the modulator is ensured to work under proper bias voltage.