Broadband all-digital variable fiber-optic attenuator using digital micromirror device

To the best of our knowledge, we propose the first broadband variable fiber-optic attenuator (VFOA) using a digital micromirror device (DMD). The VFOA design is based on a unique double reflection geometry structure that counters the strong spectral attenuation inherent when implementing single-mode-fiber light coupling via a pixelated blazed grating device such as a DMD. The demonstrated VFOA features ∼C-band 1530- to 1560-nm broadband attenuation operation with a ±0.17-dB in-band variation and a 25-dB attenuation dynamic range. This high repeatability all-digital VFOA can be useful in broadband optical source controls, test instrumentation, telecommunications, signal processing, and sensor systems.