A modulator bias controller for stabilizing the operating point of LiNbO3 Mach-Zehnder modulators has been unveiled by Photline Technologies. The MBC-1001 performs continuous tuning of the operating point over the transfer function of the modulator and accommodates the wide variety of modulation formats used in new-generation telecommunications systems. It compensates for the slight bias shift caused by the modulators’ internal monitoring photodiodes. The benchtop instrument has a front panel manual interface, a LabView graphical user interface and an RS-232 interface. It is compatible with all Mach-Zehnder modulators and can operate with the photocurrent provided by an internal monitoring photodiode or by an external tap one.