Liquid-crystal level equalizer arrays on fiber arrays

We have developed simple and inexpensive level equalizer arrays using 8- to 16-channel independent liquid-crystal (LC) variable-optical-attenuator (VOA) arrays and multichannel in-line photodetector arrays, which were integrated on fiber arrays. We used two types of LC-VOAs: 1) ultrathin LC cells inserted into trenches cut across the fiber arrays, and 2) LC filling the gap between transparent electrode-coated fibers of the fiber splicer. The pitch of the fibers was 250 μm, and the number of fibers ranged from 8 to 16. These level equalizer arrays can suppress 2-Hz power fluctuations to a desired constant power level by using a dithering feedback circuit.