Lucent Technologies Inc.

Annjoe Golangco Wong-Foy

Mahmoud Rasras

Christi Kay Madsen

Edward J Laskowski

A waveguide turn having two waveguides oriented at an angle with respect to one another and optically coupled to one another by a reflective surface. In one embodiment, the reflective surface is a side of a trench formed in the core and cladding regions of the waveguides, which is designed to reflect light based on total internal reflection (TIR). The reflective surface can be designed to have an appropriate curved shape to reduce coupling losses between the waveguides. Due to relatively sharp turn (reflection) angles accessible with the reflective surface, the circuit area occupied by a waveguide turn of the invention is significantly smaller than that for a typical prior-art waveguide turn.

Waveguide turn for a waveguide circuit

In accordance with the invention, a high speed thermo-optic phase shifter comprises a length of optical waveguide including a waveguiding core of a first material having an index of refraction nand a first order temperature dependence |dn/dT| and, optically coupled to the core, a length of a second material having an index npreferably greater than the core (n&#x3e;n) and a first order temperature dependence |dn/dT| than the core (|dn/dT|&#x3e;|dn/dT|). Advantageously, the length of second material is adiabatically tapered at both ends. Upon heating, as by a resistance heater, the second material changes the optical pathlength by an amount predominantly determined by |dn/dT| providing faster switching speed. In a preferred embodiment, the core comprises silica, and the second material comprises silicon to produce switching speeds up to a few hundred MHz.

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Basking Ridge, NJ, United States of America

Annjoe Golangco Wong-Foy