Pre-tilted MEMS Mirrors for Optical Cross-connect Reliability
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Solution Overview
Problem
In optical cross-connect systems, the increased range of angular rotation required for outer MEMS mirrors leads to higher stress and reduced reliability due to the need for more advanced actuators, which can decrease the lifetime of MEMS mirror elements as system sizes increase.
Innovation Solution
The implementation of pre-tilted MEMS mirrors by sloping the substrates or using pre-tilted mounting blocks reduces the range of rotation required for exterior mirrors, allowing for simpler and more reliable actuators by distributing the rotation demand more evenly across the mirror array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mirror array size is increased to expand system capacity, then the switching capability is improved, but the required angular rotation range of outer mirrors increases, leading to higher stress and reduced reliability
Solution Approach 1:
The patent applies different tilt angles to mirrors based on their position within the array. Outer mirrors are pre-tilted at a greater angle toward the center than inner mirrors, allowing each mirror to have optimized local characteristics that reduce stress while maintaining overall system capacity
Solution Approach 2:
The mirrors are pre-tilted during manufacturing or assembly to an initial angle that reduces the subsequent rotation range required during operation. This preliminary positioning reduces the mechanical stress and actuator requirements, thereby improving reliability while maintaining expanded system capacity
2Adaptability or versatility
If the angular rotation range of outer mirrors is increased to ensure proper reflection coverage, then the optical coverage is improved, but the actuator performance requirements and structural stress increase, reducing reliability
Solution Approach 1:
Different mirrors are assigned different pre-tilt angles according to their specific position and optical requirements. Outer mirrors receive greater pre-tilt angles to redirect light toward the center, while inner mirrors have smaller pre-tilt angles, optimizing both coverage and reliability for each location
Solution Approach 2:
The patent changes the pre-tilt angle parameter of mirrors based on their position in the array. By adjusting this geometric parameter, the system achieves comprehensive optical coverage while reducing the dynamic rotation range and associated stress on actuators and structures
Data Source
AI summary
A micro-electro-mechanical systems (MEMS) mirror array can include pre-tilted mirrors. In some implementations, a MEMS mirror array includes a set of first MEMS mirrors supported by a mounting surface of one or more first substrates, and a set of exterior MEMS mirrors supported by a mounting surface of one or more exterior substrates. The one or more exterior substrates can be disposed along at least one edge of an exterior perimeter of at least one of the first substrates. The mounting surface of the one or more exterior substrates can be arranged to cause a plane of each exterior MEMS mirror to be at a non-zero angle with respect to each first MEMS mirror. The one or more first substrates and the one or more exterior substrates can be supported by a common substrate.