A 2x2 Mach-Zehnder optical switch design with a footprint of 0.5 um x 2.5 um using nanomechanical gap plasmon phase modulators  is presented. The extremely small footprint and modest optical loss are enabled by the strong phase modulation of gap plasmons in a mechanically actuated 17 nm air gap. Frequency-domain finite-element modeling at 780 nm shows that the insertion loss is ≤ 8.5 dB, the extinction ratio is > 25 dB, and crosstalk for all ports is > 24 dB. A design optimization approach and its dependence on geometrical parameters are discussed.
switch, phase modulator, opto-mechanical, gap plasmon, Mach-Zehnderv