Structures that correct for thermal distortion in an optical device formed of thermally dissimilar materials

#1. Field of the Invention

#The field of the invention is structures that correct for thermal distortion in a device and more particularly, is MEMS (Micro Electro Mechanical Systems) and MOEMS (Micro Optical Electrical Mechanical Systems) structures that correct for thermal distortion in a device.

#2. Background

#The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.

#FIG. 1 is a schematic representation of an optical switch that compensates for thermal distortion.

#FIG. 2 is a schematic representation of the optical switch of FIG. 1 as taken along view 2A—2A and illustrates the effects of thermal distortion on the alignment of the waveguides.

#The novel thermal compensation flexure described here reduces the effect of thermal distortion on structures such as optical devices. The thermal compensation flexure preferably is formed of dissimilar materials and yet maintains selective and accurate optical alignments between light guiding structures. The thermal compensation flexure may be used in any designs where a thermal distortion is induced onto a suspended structure and where an accurate alignment between a suspended structure and a stationary structure is required. For example, one such case is where an optical component such as a waveguide is mounted to a structure and the combined hybrid structure is subjected to a temperature change. In the preferred embodiment, the optical component is a waveguide or any other light guiding element which directs an optical signal along an optical path following the contour of the structure.

#FIG. 1 is a schematic representation of an optical switch that has a thermal compensation flexure which compensates for thermal distortion. In FIG. 1, the optical switch is capable of switching the incoming light (A) to any of the output channels B, C, D by moving the position of the suspended structure 10 relative to fixed structures 14, 15. As shown in FIG. 1, the suspended structure 10 is positioned such that an incoming optical signal from input port (A) passes through waveguide 16 on fixed structure 14 to the middle waveguide 20 on suspended structure 10, and then to the middle waveguide 17 on fixed structure 15 to output port (C). For example, if the suspended structure 10 were moved (say, downward) relative to fixed structures 14, 15, the incoming optical signal from input port (A) would pass through waveguide 16 on fixed structure 14 to the upper waveguide 20 on suspended structure 10, and then to the upper waveguide 17 on fixed structure 15 to output port (B). Likewise, if the suspended structure 10 were moved upward relative to fixed structures 14, 15, the incoming optical signal from input port (A) would pass through waveguide 16 on fixed structure 14 to the lower waveguide 20 on suspended structure 10, and then to the lower waveguide 17 on fixed structure 15 to output port (D). Of course, numerous variations to the optical switch are possible so that the optical switch may employ any number of input ports, any number of output ports, any number of fixed waveguides, any number of movable waveguides, any number of movable or suspended structures, any number of fixed structures, and any possible combination of these numbers. To move the structure 10, an electrical voltage is applied across the electrodes 18, 19. Additional details of this optical switch and its operations are disclosed in (1) provisional U.S. Patent Application Ser. No. 60/233,672 by Ying Wen Hsu, filed on Sep. 19, 2000 and titled “Method For Switching Optical Signals Using Microstructures;” (2) provisional U.S. Patent Application Ser. No. 60/241,762 by Ying Wen Hsu, filed on Oct. 20, 2000, titled “Method for switching optical signals using microstructures;” (3) U.S. patent application Ser. No. 09/837,829 by Ying Wen Hsu, filed on Apr. 17, 2001 and titled “Optical Switching Element Having Movable Optically Transmissive Microstructure;” (4) U.S. patent application Ser. No. 09/837,817 by Ying Wen Hsu, filed on Apr. 17, 2001 and titled “Optical Switching System That Uses Movable Microstructures To Switch Optical Signals In Three Dimensions,” all patent applications of which have been incorporated herein by reference.

#A structure 10 is suspended by thermal compensation flexures 12, 13 over substrate. In this particular embodiment, the thermal compensation flexures 12, 13 are folded springs. Although the terms “spring” and “folded spring” are used, the term “flexure” is more appropriate because the structure need not be an actual spring and can be any kind of flexible structure. Thus, for each and every embodiment and for all purposes in this disclosure, the term “spring” or “folded spring” shall be construed broadly to include any kind of flexure and the term “flexure” shall also be construed broadly to include both spring-like flexures and non-spring like flexures. The structure 10 has on its top at least one waveguide 20 that can direct light along its length. Preferably, the structure 10 has a plurality of waveguides 20. Adjacent to the suspended structure 10 are two stationary structures 14, 15 with waveguides 16, 17 respectively residing on them.