PIC Optical Inspection Using Linear Dichroic Wavelength Separation
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Solution Overview
Problem
Existing inspection methods for photonic integrated circuits (PICs) cannot acquire wavelength information about light output, hindering appropriate inspection processes.
Innovation Solution
An inspection apparatus and method that utilize an optical filter with a linearly varying transmittance characteristic to transmit and reflect light based on wavelength, capturing and analyzing image data to derive wavelength information from optical output units in PICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical filter with linearly varying transmittance is used to capture wavelength information, then measurement precision of wavelength information is improved, but device complexity increases due to additional optical components and dual image sensors
Solution Approach 1:
The optical system is segmented by introducing an optical filter that divides light into different wavelength ranges, with each segment captured by dedicated image sensor regions. This segmentation enables wavelength-specific measurement while maintaining system manageability through modular optical component design.
Solution Approach 2:
An optical filter serves as an intermediary component between the light source and image sensors, mediating the wavelength information extraction process. The filter's linearly varying transmittance characteristic acts as a spectral mediator that enables accurate wavelength measurement without requiring complex spectrometric equipment.
2Productivity
If multiple optical output units are inspected simultaneously, then productivity is improved, but measurement precision may deteriorate due to increased complexity in deriving wavelength information from multiple sources
Solution Approach 1:
Multiple optical output units are merged into a single inspection field of view, with light from all units simultaneously captured by the image sensors. The optical filter and dual-sensor system process all wavelength information in parallel, enabling high-speed multi-point inspection without sacrificing measurement precision through unified data processing.
Solution Approach 2:
The optical inspection system achieves multi-functionality by simultaneously inspecting multiple optical output units with different wavelength characteristics using a single integrated system. The universal design allows the same optical filter and sensor configuration to handle various wavelength ranges and multiple light sources concurrently.
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
Enables accurate acquisition of wavelength information, allowing for thorough inspection of PICs, including channel accuracy and detection of defects, and facilitates temperature-controlled adjustments for enhanced inspection precision.
Implementation Method 1
an optical filter having a transmission characteristic in which transmittance varies linearly in a predetermined wavelength range and configured to transmit and reflect light guided by the waveguide and output from at least one optical output unit on the basis of the transmission characteristic
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
An inspection apparatus 1 includes a stage 10 configured to hold a PIC 100, a PIC controller 20 configured to control an operation of the PIC 100, an LRG dichroic mirror 61 having a transmission characteristic in which transmittance varies linearly in a predetermined wavelength range and configured to transmit and reflect light guided by a waveguide 108 and output from at least one optical output unit 102 on the basis of the transmission characteristic, a first camera 62 configured to capture the light transmitted through the LRG dichroic mirror 61 to output a transmission image, a second camera 63 configured to capture the light reflected by the LRG dichroic mirror 61 to output a reflection image, and a computer 70 configured to execute a first process for deriving wavelength information about light output from the optical output unit 102 on the basis of the transmission image and the reflection image.