The OVA-640 is a compact optical variable attenuator from Santec Corp. that uses a stepper motor for precise electrical control. The device has high resolution, low insertion loss and low wavelength dependence. It operates in the 1550- or 1310-nm range and has a maximum attenuation of >15 dB. The OVA-640 is suitable for controlling optical amplifier gain, transmitter power and channel levels. The attenuator can be mounted on a printed circuit board for system integration.