Multimode Interferometer Waveguide Out-of-Plane Scattering Analysis
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Solution Overview
Problem
Existing techniques for imaging multimode interference patterns in MMI-WGs are limited by the need for single-wavelength operation and require long waveguides to separate patterns formed by different wavelengths, making precise fabrication and tuning necessary.
Innovation Solution
The system employs out-of-plane imaging by collecting scattered light from the top or bottom face of the MMI-WG, using an image sensor to generate data on the intensity of scattered light, and processing this data to determine the spectrum of light propagating through the waveguide, allowing for simultaneous analysis of multiple wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If in-plane imaging of spot patterns is used, then wavelength separation is achieved, but only single-wavelength operation is effective and long waveguides are required
Solution Approach 1:
The patent transitions from in-plane imaging (2D detection within the waveguide plane) to out-of-plane imaging (3D detection by collecting scattered light above or below the waveguide). This dimensional change allows simultaneous separation of multiple wavelengths without requiring extended propagation distances, as the scattered light carries wavelength-dependent spatial information that can be captured in a single transverse plane.
Solution Approach 2:
The patent introduces scattered light as an intermediary carrier that mediates between the propagating light modes and the detector. By collecting light that scatters out of the waveguide at angles dependent on the interference pattern, the system transfers wavelength information to the angular/spatial distribution of scattered light, enabling compact spectral analysis without long propagation distances.
2Measurement precision
If in-plane spot pattern imaging is used, then spectral information is obtained, but precise fabrication and tuning are required
Solution Approach 1:
By moving the detection plane from in-plane to out-of-plane, the system accesses a different spatial domain where the interference information is encoded in the angular distribution of scattered light rather than requiring precise in-plane spot positioning. This reduces sensitivity to fabrication tolerances in the waveguide dimensions while maintaining spectral measurement capability.
Solution Approach 2:
The patent changes the detection parameter from positional coordinates within the waveguide plane to angular coordinates of scattered light. This parameter transformation makes the measurement less sensitive to absolute dimensional tolerances and more robust to fabrication variations, as the angular distribution pattern is determined by the interference physics rather than absolute geometric precision.
3Productivity
If out-of-plane imaging of scattered light is used, then multiple wavelengths can be analyzed simultaneously and waveguide length is reduced, but scattered light collection efficiency must be sufficient
Solution Approach 1:
The out-of-plane detection scheme serves multiple functions simultaneously: it enables multi-wavelength analysis, reduces the required waveguide length, and provides robustness against fabrication variations. The scattered light collection geometry is designed to capture interference information across the spectral range of interest, making the system universally applicable to various wavelength combinations without requiring separate optimization for each wavelength.
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 approach enables efficient spectrometry and particle identification without the need for well-resolved in-plane spot patterns, allowing for shorter waveguides and reduced fabrication complexity, while still achieving accurate determination of light spectra and particle identities.
Implementation Method 1
As the propagating light travels in different modes with different propagation speeds, the light may constructively and destructively interfere with itself to form spatially-distributed peaks and valleys of intensity
Implementation Method 2
an image sensor may be disposed above or below the MMI-WG to collect the scattered light and to generate image data based on the scattered light collected
Data Source
AI summary
Systems and methods for spectroscopic analysis and particle identification using out-of-plane imaging of multimode-interferometer waveguide (MMI-WG) scattering are provided. A MMI-WG comprises an input end, a lateral surface, and an input port disposed on the input end, such that light in the MMI-WG propagates in a direction away from the input end. A sensor is configured to detect scattered light that scattered through the lateral surface of the MMI-WG, and to generate data based on the detected scattered light, wherein the data indicates an intensity of the scattered light. One or more processors are configured to determine, based on the intensity of the scattered light indicated by the data generated by the sensor, one or more wavelengths of the input light. The identity of one or more particles may be determined based on the one or more determined wavelengths.