Small-tilt micromirror-device-based multiwavelength three-dimensional 2×2 fiber optic switch structures

Small-tilt micromirror-based 2×2 fiber optic switch array structures are proposed using fixed mirrors and fiber interconnections. A multiwavelength 2×2 fiber optic switch based on this small-tilt micromirror is experimentally demonstrated. The key innovation in this architecture is the use of a specially located fixed mirror to form a symmetric 2×2 retroreflective switching structure. These 2×2 fiber optic switch structures can also provide a fault-tolerant design using a macropixel approach. A two-dimensional digital micromirror device (2D-DMD) from Texas Instruments (TI) designed to operate in the visible band is used to represent the small-tilt micromirrors in our experimental demonstration. Multiwavelength switch operation is characterized by changing the operating wavelength of the tunable laser. The measured average optical coherent crosstalk is -22 dB with ±0.9 dB fluctuation over 40 nm, limited by the on-off ratio of the 2D-DMD. The measured average optical loss is 14.8 dB at a 1.55-μm operating wavelength, limited by the visible wavelength design TI 2D-DMD, three-port optical circulators, fiber adapters, and free-space-to-fiber coupling efficiency.