The Precision Ditherless Bias Controller (MBC-PDBC) is an OEM, standalone device designed for precise bias control in feedback loops. It provides accurate modulator biasing using a pilot tone mode to bring the modulator to the Quad position, followed by a ditherless mode to maintain that position.

The unit can also operate in manual mode to lock the bias to a specific working point without a pilot tone. The locking slope is adjustable via a jumper on the board. Built-in photodiodes provide feedback for real-time adjustments, while an external reference voltage can be applied upon request.

This controller ensures stable and precise locking, even when the modulator drifts out of the desired range, and can quickly bring the system back to the correct point. Its fast response, high dynamic range, and high accuracy make it ideal for applications such as Mach-Zehnder modulators and Fabry-Perot fiber control loop-back systems. The unit also features an alarming LED for overtuning, providing further system reliability.