Page 205 - Optofluidics Fundamentals, Devices, and Applications

180 Cha pte r Ei g h t

Wave guides
Liquid Add signal Fluid In signal
Bubble Trench
Center heater
Optical
waveguide
Sidewall
metalization

Bubble
Drop signal Out signal
(a) (b)
Mirror channel

Flow channels 2 mm 3 4 5
2
1 2
1
Inlet 1 Inlet 2 Outlet
Laser
beams Control channels
1 Vent 2 3, 4 5
(c) (d)
FIGURE 8-1 Three switches are shown: planar bubble switch (a and b), microfl uidic 2 × 2
switch (c and d), and diffractive 1 × 4 switch (e and f). (a) Basic component of a bubble
switch—cross point between four optical waveguides with a fl uidic channel between
them. Thermally generated bubble introduced into the cross point refl ects the light into a
waveguide. (b) Layout of N × N bubble switch showing a matrix of input-output planar
waveguides. (S. Hengstler, J.J. Uebbing, and P. McGuire, “Laser-activated optical bubble
switch element,” Proceedings of the 2003 IEEE/LEOS International Conference on
Optical MEMS (OMEMS) 2003), copyright 2003 IEEE.) (c) Complete 3-layer elastomer
chip with 4 optical quality facets (the arrows on the left show directions of incident laser
beams 1 and 2, and the arrows on the right show transmitted and refl ected beams).
(Reprinted with permission from K. Campbell, A. Groisman, U. Levy, L. Pang, S.
Mookherjea, D. Psaltis, and Y. Fainman, “A microfl uidic 2 × 2 optical switch,” Appl. Phys.
Lett, 85, 6119–6121, 2004. Copyright 2004, American Institute of Physics.) (d)
Microphotograph of the 2 × 2 switch device (control layer inlets are labeled by numbers
of the membrane valves they actuate). (Reprinted with permission from K. Campbell,
A. Groisman, U. Levy, L. Pang, S. Mookherjea, D. Psaltis, and Y. Fainman, “A microfl uidic
2 × 2 optical switch,” Appl. Phys. Lett, 85, 6119–6121, 2004. Copyright 2004,
American Institute of Physics.) (e) Fabricated 1 × 4 switch based on diffraction grating.
(A. Groisman, S. Zamek, K. Campbell, L. Pang, U. Levy, and Y. Fainman, “Optofl uidic
1 × 4 switch,” Opt. Express, 16 (18), 13499–13508, 2008.) (f) Concept of operation of
1 × N optical switch—the fl uid on top of the grating is replaced to redirect the beam into
a certain order; the beam is incident from the bottom of the chamber shown on the
fi gure. (A. Groisman, S. Zamek, K. Campbell, L. Pang, U. Levy, and Y. Fainman,
“Optofl uidic 1 × 4 switch,” Opt. Express, 16 (18), 13499–13508, 2008.)