High speed thermo-optic phase shifter and devices comprising same

• Main Authors: MADSEN CHRISTI KAY, LASKOWSKI EDWARD JOHN, WONG-FOY ANNJOE GOLANGCO
• Format: Patent
• Language: English
• Published: 02.12.2004
• Edition: 7
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

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 n1 and a first order temperature dependence |dn1/dT| and, optically coupled to the core, a length of a second material having an index n2 preferably greater than the core (n2>n1) and a first order temperature dependence |dn2/dT| than the core (|dn2/dT|>|dn1/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 |dn2/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.