Micromechanical tunable Fabry-Perot interferometer and a method for producing the same
AssigneeTeknologian tutkimuskeskus VTT Oy
InventorMikko Tuohiniemi
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Abstract
Electrically tunable Fabry-Perot interferometers produced with micro-optical electromechanical (MOEMS) technology. Micromechanical interferometers of the prior art require high control voltage, their production includes complicated production phases, and the forms of the movable mirrors are restricted to circular geometries. In the inventive solution, there is a gap in the movable mirror, whereby mirror layers opposite to the gap are connected with anchoring. The anchoring is such that the stiffness of the mirror is higher at the optical area than at the surrounding area. This way it is possible keep the optical area of the mirror flat even if the control electrodes extend to the optical area. Due to large electrodes, lower control voltages are required.
Claims14
An electrically tunable Fabry-Perot interferometer, comprising:
- a substrate,
- a first mirror on the substrate,
- a second, movable mirror,
- the second mirror has a movable optical area and a movable area surrounding the optical area,
- a Fabry-Perot cavity between the first and second mirrors,
- the first and second mirror have electrodes for electrical control of the distance between the mirrors,
- at least the surrounding area of the second mirror has a gap between two layers of the mirror, and mirror layers at the opposite sides of the gap are connected with anchoring through the gap, wherein,
- the electrodes of the first and second mirrors extend to the optical area, and
- the implementation of the anchoring is such that the stiffness of the surrounding area is lower than the stiffness of the optical area, whereby the movable mirror is arranged to bend more at the surrounding area than at the optical area on activation of the electrodes with a control voltage,
- the second, movable mirror includes a gap also at the optical area, and
- the density of anchors in the gap of the second, movable mirror is higher at the optical area than at the surrounding area.
Method for producing an electrically tunable Fabry-Perot interferometer, wherein:
- a substrate is provided,
- a first mirror is provided on the substrate,
- a second, movable mirror is provided, wherein the second mirror has a movable optical area and a further movable area surrounding the optical area,
- a Fabry-Perot cavity is provided between the first and second mirrors,
- electrodes are provided for the first and second mirrors for electrical control of the distance between the mirrors,
- a gap is provided between two layers of the mirror in at least the surrounding area of the second mirror, and anchoring is provided for connecting mirror layers at the opposite sides of the gap with the anchoring through the gap, wherein,
- the electrodes of the first and second mirrors are formed to extend to the optical area, and
- the anchoring is such implemented that the stiffness of the surrounding area is lower than the stiffness of the optical area, whereby the movable mirror is arranged to bend more at the surrounding area than at the optical area on activation of the electrodes with a control voltage, and
- anchoring is provided by depositing anchors, wherein the density of anchors in the gap of the second, movable mirror is made higher at the optical area than at the surrounding area.
Dependencies are inferred from the claim text.