Optical Probe Positioning via Diffractive Element Reflection
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Solution Overview
Problem
Current optical probe position control methods for Photonic Integrated Circuits (PICs) are limited by large sensor sizes, remote operation, and inability to provide multiple height measurements, leading to inefficient and inaccurate probe positioning.
Innovation Solution
A system utilizing a diffractive optical element (DOE) with a focal point for maximum reflection, combined with a motorized positioner and power meter, allows for precise three-dimensional positioning of an optical waveguide probe by locating absolute maximum reflection points, enabling non-contact, intimate proximity optical probing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive proximity sensors or optical displacement sensors are used for probe position control, then probe height sensing capability is improved, but sensor size becomes large and requires remote operation from the probing location
Solution Approach 1:
The patent combines the sensing function directly into the probe tip by integrating a capacitive sensor that is co-located with the optical fiber probe. This merging eliminates the need for separate, large remote sensors while maintaining height measurement capability. The sensor and probe become a single integrated unit that can operate in intimate proximity to the PIC.
Solution Approach 2:
The patent introduces an intermediary approach by using the probe itself as the sensing element rather than a separate sensor. The capacitive sensor on the probe tip acts as an intermediary between the probe positioning system and the PIC, enabling direct measurement without requiring large external sensors.
2Device complexity
If single height measurement techniques are used, then device complexity is reduced, but multiple control points for probe arrays cannot be provided
Solution Approach 1:
The patent applies segmentation by providing individual capacitive sensors on each probe tip in the probe array. This allows each probe to have its own independent height measurement capability, enabling multiple control points to be monitored simultaneously. The system segments the measurement function across multiple probes rather than using a single shared sensor.
Solution Approach 2:
The patent makes the probe array system universal by designing it to accommodate multiple probes with individual sensors, allowing the same basic probe structure to serve multiple control points. Each probe in the array can independently measure height at its own location, providing versatile multi-point control capability.
3Measurement precision
If displacement sensors are used, then relative offset tracking is achieved, but absolute distance measurement capability is lost
Solution Approach 1:
The patent replaces traditional optical displacement sensors with a capacitive sensing mechanism. The capacitive sensor measures absolute distance through electrical field interaction rather than optical interference patterns. This substitution preserves absolute position information while enabling intimate proximity operation, as capacitive sensing does not require the complex optical paths needed for interferometric displacement measurement.
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 method provides accurate and repeatable optical probe positioning, reducing the need for extensive 'real estate' on the PIC and allowing for precise control of probe height and beam angle, enhancing testing reliability and efficiency.
Implementation Method 1
a diffractive optical element (DOE) disposed in the PIC, the DOE having a focal point of maximum reflection at location having coordinates in three-dimensions above the PIC
Implementation Method 2
the DOE reflects and focuses light back to the optical waveguide probe
Data Source
AI summary
A system for determining optical probe location relative to a photonic integrated circuit (PIC) is described. A diffractive optical element (DOE), which includes a plurality of lens elements, is disposed in the PIC, and has a focal point of absolute maximum reflection at location having coordinates in three-dimensions above the PIC. The system includes an optical waveguide probe, and an optical source adapted to provide light through the optical waveguide probe and incident on the DOE. The DOE reflects and focuses light back to the optical waveguide probe, and a power meter is adapted to receive at least a portion of the light reflected and focused at the focal point above the PIC. Based on the determination of a location of the absolute maximum reflection, consistent and reliable testing of PIC can be achieved.