Lucent Technologies Inc.

Anat Sneh

Vladimir Anatolyevich Aksyuk

David John Bishop

Uziel Koren

Jane Elisa Zucker

The invention provides tunable optical filters which incorporate a surface-micromachined out-of-plane plate having a moveable membrane with a high reflective (HR) coated mirror. The mirror defines one side of a Fabry-Perot (FP) filter cavity and is movable in a direction along an axis of the filter cavity. The other side of the filter cavity is defined by a second HR-coated mirror. In one illustrative embodiment, a first plate is formed on a substrate, and then subsequently released from the substrate and secured in a plane orthogonal to the substrate. The first HR-coated mirror is formed as part of a movable membrane supported in an opening through the first plate. The second mirror is formed on a second plate secured in another plane orthogonal to the plane of the substrate, such that the filter cavity is defined horizontally between the first and second mirrors. In another embodiment, the second mirror is formed on an endface of an external fiber, such that light from the fiber can pass from the second mirror through an opening in the second plate to the first mirror. In another possible embodiment, the second plate is eliminated and the second mirror is formed on the substrate. The first plate is then arranged over the second mirror, in a plane parallel to the substrate, and separated from the substrate by spacers, such that the filter cavity is defined vertically.

Surface-micromachined out-of-plane tunable optical filters

The invention provides tunable optical filters in which operating characteristics such as initial cavity length and mirror tilt, affecting passband wavelength position and filter finesse, respectively, can be controlled independently of membrane tuning bias. An illustrative embodiment incorporates a surface-micromachined plate with an opening in which a moveable frame is supported by, e.g., flexure bars or support arms. A moveable membrane with a high reflective (HR) coated mirror is supported in an opening in the moveable frame. The mirror defines one side of a Fabry-Perot (FP) filter cavity and is movable in a direction along an axis of the filter cavity. The other side of the filter cavity is defined by a second HR-coated mirror. The moveable frame has a number of electrodes arranged on a surface thereof, such that an operating characteristic of the filter, e.g., the cavity length affecting the passband wavelength position or the mirror tilt affecting the filter finesse, can be adjusted by applying signals to at least a subset of the electrodes. The use of a separate set of electrodes for controlling the moveable frame permits the operating characteristic to be adjusted independently of a tuning bias applied to one or more additional electrodes associated with the moveable membrane.

Micromachined tunable optical filter with controllable finesse and passband wavelength position

Methods and apparatus for performing optical signal switching or other optical routing functions in an optical device or system, in which crosstalk induced by modal interference is suppressed by providing appropriate loss, gain and/or refractive index changes in different parts of a switch structure. An exemplary optical signal switch includes first and second branches each having a refraction-controlled section and an absorption-controlled section. An optical signal path over which an optical signal propagates in passing through the switch is selected to include a portion of at least one of the first and second branches, such that one of the first and second branches is a selected branch and the other branch is a non-selected branch. The refraction-controlled section of the selected branch is configured in a high effective refractive index state which allows the optical signal to propagate along at least a portion of the selected branch, while the refraction-controlled section of the non-selected branch is configured in a low effective refractive index state. The absorption-controlled section of the selected branch is configured in a low absorption state, while the absorption-controlled section of the non-selected branch is configured in a high absorption state to reduce crosstalk within the optical switch. An effective refractive index in a given refraction-controlled section may be provided using electro-refractive techniques such as the quantum-confined Stark effect (QCSE) or the Franz-Keldysh effect, or by carrier-induced effects such as carrier injection or carrier depletion. An absorption change in a given absorption-controlled section may be provided using electro-absorptive techniques or a gain-switching technique. The switch may be configured as a Y-branch switch, a directional coupler, or in other suitable configurations, and may be interconnected with other similar switches to construct 1.times.N, N.times.1, N.times.M and N.times.N switch arrays.

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Branchburg, NJ, United States of America

Anat Sneh