Total internal reflection optical switches employing thermal activation

Abstract

A switching element defines a transmitting state and a reflecting state for a pair of intersecting waveguides that have a gap at their intersection. In the preferred embodiment, the switching element exhibits total internal reflection at the gap sidewall from one waveguide to the other when not in the transmitting state. In the transmitting state, index-matching liquid fills the gap, enabling light to continue in the original waveguide direction. The switching element may use ink jet techniques or bubble techniques to displace index-matching liquid. The index-matching fluid may be projected from a gap between the waveguides by a jet mechanism, or a vapor or dissolved gas bubble may be formed to fill the gap between the waveguides to provide the reflecting state for the switching element. Using either of the techniques, heaters are employed to initiate the switching operation. In some embodiments, more than one heater is utilized. In the preferred embodiment, waveguides are formed on one substrate and heaters are formed on another. Then the substrates are aligned and bonded together to position the heaters in very close proximity to the intersection between the waveguides. Preferably, the switching element is one element in a matrix of such elements for routing signals between arrays of input and output waveguides.