Versatile multi-wavelength fiber-optic switch and attenuator structures using mirror manipulations

Compact frequency-selective fiber-optic switch (FOS) and attenuator structures are proposed based on the use of 2N hinge-type flapping micromirrors in a linear array geometry and piston-type micromirrors in a two dimensional (2D) array format. The flapping micromirrors are designed to be positioned in a compact low-loss in-line geometry that provides ease in optical alignment. The results of an experimental 4-wavelength proof of concept FOS using two macro-mirrors shows an average optical interchannel crosstalk of < -33 dB and an average total loss of < 10.8 dB. Both numbers are limited by other devices in our self-aligning structure, as the unique in-line mirror placement design provides a low 0.4 dB free-space coupling average optical loss. Using sub-micrometer motion of 2D piston-type micromirrors, an alternate higher speed FOS based on the Michelson interferometer structure is proposed. Experimental proof of concept data for this FOS indicates an average optical loss of 9.81 dB and a loss fluctuation of ±0.06 dB within a 50 nm bandwidth. This optical loss value is again limited by the WDM devices, fiber adapters, three-port optical circulators, and free-space coupling efficiency. An average optical interchannel crosstalk of -24.4 dB is measured, limited by the resolution of the translation stage used in the experiment. Using these FOS architectures, variable fiber-optic attenuator structures are also introduced. An average maximum optical attenuation of 24.38 dB is measured within a 50 nm bandwidth for our attenuator using the interferometric FOS design.