Monolithic Interferometric Optical Sensor for Low Cross-Sensitivity
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Solution Overview
Problem
Existing optical sensor arrangements are limited in their application scope and suffer from cross-sensitivity issues, making them less effective in detecting specific measured variables due to interference from other influences.
Innovation Solution
An integrated optical sensor arrangement with a monolithic interferometer design, featuring a carrier with waveguide structures formed by ion exchange or CVD, where a measuring conductor and a reference conductor are parallel and symmetric, with a measuring-active side face allowing one-sided interaction, enabling asymmetrical changes in optical path length to be recorded using the interferometric principle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional optical sensor arrangements are used, then they can detect measured variables, but they suffer from cross-sensitivity issues and limited application scope
Solution Approach 1:
The patent applies asymmetry by creating an asymmetric interaction between the measured quantity and the sensor element. The measuring conductor is positioned asymmetrically relative to the reference conductor, with the measuring conductor being closer to the measurement-active side surface. This asymmetric configuration ensures that only the measuring conductor is affected by the measured quantity (force, vibration, or substance), while the reference conductor remains unaffected, thereby eliminating cross-sensitivity and expanding application scope across multiple measurement types.
2Measurement precision
If interferometric measurement principle is used, then detection sensitivity is improved, but device complexity increases
Solution Approach 1:
The patent merges the interferometer structure directly into the optical chip, integrating the measuring conductor and reference conductor in a planar configuration on the same substrate. This integration combines multiple functions (interference pattern generation, signal splitting, and differential measurement) into a single compact device, maintaining high detection sensitivity while reducing overall device complexity compared to traditional separate-component interferometric systems.
3Ease of manufacture
If symmetric waveguide structures are used, then manufacturing is simplified, but selective detection of specific measured variables is reduced
Solution Approach 1:
The patent applies local quality by creating a specific asymmetric configuration only where needed for measurement interaction. The measuring conductor is positioned closer to the measurement-active side surface than the reference conductor, creating a localized asymmetric interaction zone. This allows the bulk of the waveguide structure to remain relatively simple for manufacturing, while the critical measurement region achieves the necessary asymmetry for selective detection of specific measured variables without compromising overall manufacturability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a highly sensitive, compact, and selective detection of the desired measured variable with low cross-sensitivity, allowing for precise measurement of forces, vibrations, and substances without interference from other influences.
Implementation Method 1
The waveguide structure can be embedded in various ways. Preferably, the waveguide structures are formed by an ion exchange process
Implementation Method 2
Due to the one-sided effect only on the measuring-active side surface, or the one-sided interaction with the measuring-active side surface, an asymmetric interaction of the measured quantity with the sensor element occurs, such that this interaction results in an asymmetric change in the optical path length of the measuring conductor compared to the reference conductor. This change in optical path length is detected using the underlying interferometric measurement principle.
Data Source
Figure 1~2E
Figure 3~6
AI summary
The invention relates to a sensor element for forming a miniaturized, monolithic interferometer arrangement for detecting a measured variable. Said sensor element has a substrate (4) extending in the longitudinal direction and a waveguide structure (6). In order to form an interferometer, the waveguide structure (6) has a reference conductor (22) and a measuring conductor (20), which are guided in parallel beside each other. In order to detect the measured variable, the sensor element (2) has a lateral, actively measuring side surface (12A), on which the measured variable to be detected acts, such that an asymmetric interaction between the measured variable and the waveguide structure (6) takes place and varies the optical path length of the measuring conductor (20) in relation to the reference conductor (22). This difference in path length is evaluated electronically by the interferometer.