As module for 8164B lightwave measurement system, 81606A accelerates automated adjustment of wavelength-selective devices to facilitate device verification. Respective tuning ranges for Option 216 and 116 are 1,450–1,650 nm and 1,490–1,640 nm. While cavity and laser module design promotes dynamic range, wavelength reference unit maximizes accuracy. Feedback controls and drive mechanics enable accelerated sweeps without impacting specified dynamic accuracy.