Integrated monolithic optical bench containing 3-D curved optical elements and methods of its fabrication

Description

Embodiments of the present invention provide an optical system, such as a monolithic optical bench, that includes a substrate and a three-dimensional curved optical element etched in the substrate such that an optical axis of the optical system lies within the substrate and is parallel to the plane of the substrate. In one embodiment, a moveable optical element is further etched in the substrate and a Micro-Electro-Mechanical Systems (MEMS) actuator is coupled to the moveable optical element. In an exemplary embodiment, the three-dimensional curved optical element is the moveable optical element. For example, the three-dimensional curved optical element can be coupled to the MEMS actuator and configured to move in-plane with respect to the substrate to tune a distance traveled by an optical beam propagating parallel to the plane of the substrate or out-of-plane with respect to the substrate to tune a position of the optical axis. In another exemplary embodiment, the optical system further includes a flat element formed on the substrate, in which the flat element has a flat surface perpendicular to the optical axis. In this embodiment, the flat element and/or the three-dimensional curved optical element may be the moveable optical element. In addition, the three-dimensional curved optical element can be fabricated using a first etching mask and the flat element can be fabricated using a second etching mask, in which the three-dimensional curved optical element can be protected in a shadow region under the second etching mask during fabrication of the flat element. In a further embodiment, the substrate includes a handle layer, a device layer and an etch stop layer between the handle layer and the device layer. In an exemplary embodiment, the three-dimensional curved optical element is fabricated using multiple time-controlled etching steps in one of the device layer and the handle layer, in which the multiple time-controlled etching steps include at least one anisotropic etching step, at least one surface-protection step and at least one isotropic etching step, in which the etching depths of the etching steps are related to a target surface profile of the three-dimensional curved optical element. In this embodiment, a radius of curvature of the three-dimensional curved optical element can be based on the size of the mask opening and the etching parameters. In another exemplary embodiment, a concave surface of the three-dimensional curved optical element is fabricated by continuously changing etching parameters during an anisotropic etching step that etches through a small mask opening in one of the device layer and the handle layer. In this embodiment, a radius of curvature of the three-dimensional curved optical element is based on the size of the mask opening and the etching parameters. Embodiments of the present invention further provide a method for fabricating an optical system on a substrate. In the method, a three-dimensional curved optical element is etched in the substrate such that an optical axis of the optical system lies within the substrate and is parallel to the plane of the substrate.

Aspects

The present invention relates in general to optical bench systems, and in particular to the production of monolithic optical bench systems micro-machined on a substrate.

Patenting Status

Pending

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