Fault-tolerant dense multiwavelength add-drop filter with a two-dimensional digital micromirror device

A two-dimensional digital micromirror device- (DMD-) based add-drop filter is introduced for dense wavelength-division multiplexed applications. Features of the filter include polarization-insensitive operation, low interchannel cross talk parallel processing, and a fault-tolerant design. Experiments include evaluation of a parallel-beam-fed interchannel cross-talk with a 25-beam mask and a three-color (red, green, blue) filter operational test that indicates output-port average switching optical signal-tonoise and multiwavelength cross-talk ratios of 24 dB. The DMD-based average optical loss for the filter is −2.85 dB for visible-light free-space operation, whereas a −8.88-dB optical loss is measured for a fiber-coupled filter operating at 1319 nm.