Surface Waveguide Imaging Spectrometer With Evanescent Field Detection
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Solution Overview
Problem
Current imaging spectrometers are large, mass-demanding, and costly, with limited spectral resolution and crosstalk issues in miniaturized designs, and require bulky optics and sophisticated electronics for data collection.
Innovation Solution
A compact waveguide imaging spectrometer with integrated detector arrays and surface waveguides, manufactured using femto-second laser pulse techniques, allowing direct detection of evanescent waves without image transfer optics, and enabling a stackable push-broom configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional dispersive instruments with all-mirror systems are used for wide spectral range imaging, then measurement precision and spectral coverage are improved, but device complexity, size, and mass increase significantly
Solution Approach 1:
The patent replaces traditional mechanical all-mirror dispersive systems with an integrated photonic chip-based waveguide system. Light is guided through sub-wavelength waveguides etched in a substrate, eliminating the need for bulky mirrors and mechanical moving parts while achieving comparable or superior spectral resolution through evanescent field coupling to detector elements.
Solution Approach 2:
The invention transitions from three-dimensional optical path manipulation using mirrors to two-dimensional planar waveguide structures on a chip. The spectral dispersion is achieved through spatial variation of waveguide dimensions and coupling positions in the planar domain, rather than through three-dimensional mirror arrangements.
2Measurement precision
If traditional imaging spectrometers are designed for high spectral resolution, then measurement precision is improved, but device size and mass increase
Solution Approach 1:
The patent achieves high spectral resolution by precisely controlling waveguide geometric parameters (width, height, spacing) and the positions of evanescent field couplers along the waveguide length. By varying these parameters, the effective optical path length and coupling strength are controlled, enabling high spectral resolution in a compact footprint.
Solution Approach 2:
The spectrometer is segmented into multiple independent waveguide channels, each coupled to individual detector elements. This segmentation allows parallel spectral measurement across multiple spatial positions (imaging capability) while maintaining high spectral resolution in each channel through precise waveguide design.
3Volume of moving object
If miniaturized spectrometer designs are implemented, then device volume and mass are reduced, but crosstalk between detection elements increases
Solution Approach 1:
The patent extracts and separately optimizes the light coupling function from the detection elements. Evanescent field couplers are positioned at specific locations along the waveguides to sample light at defined points, while detector elements are placed in close proximity but optically isolated. This separation allows tight packing for miniaturization while maintaining spectral independence through controlled coupling geometry.
4Ease of manufacture
If integrated photonic chip designs are used, then ease of manufacture and device compactness are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs standard photonic fabrication techniques (e.g., photolithography, reactive ion etching) that are universally applicable to various substrate materials and wavelength ranges. The same manufacturing process can produce waveguides for different spectral regions by adjusting geometric parameters, reducing the need for specialized high-precision tooling while maintaining performance.
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
Achieves a highly compact, cost-effective, and efficient imaging spectrometer with improved spectral resolution and reduced crosstalk, suitable for space-borne applications and hyperspectral imaging.
Implementation Method 1
each waveguide is extending from an inlet face proceeding partly through the substrate layer to a reflecting element
Implementation Method 2
a reflecting element, wherein a multiplicity of photo detectors is arranged on a front side of the substrate layer, allowing out-coupling of evanescent fields from each waveguide
Implementation Method 3
allowing out-coupling of evanescent fields from each waveguide at the positions of the photo detectors, while the photo detectors are applicable as evanescent field samplers
Data Source
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AI summary
The disclosed invention consists of a waveguide spectrometer (1), comprising at least one substrate layer (10) with at least one waveguide, each waveguide is extending from an inlet face (12) proceeding partly through the substrate layer (10) to a reflecting element (13), wherein a multiplicity of photo detectors (14) is arranged on a front side (I) of the substrate layer (10), while the photo detectors (14) are electrically connected to an electronic read out system, which should be lightweight and easier to produce. This is reached by forming the waveguides as surface waveguides (11, 11', 11", 11"'), each showing a longitudinal opening (110) with a width (D) to the front side (I) of the substrate layer (10) between the inlet face (12) and the reflecting element (13), while the photo detectors (14, 14', 14", 14"') are in print distributed at the front side (I) on top of the substrate layer (10) at least partly overlapping the longitudinal opening (110) of the surface waveguide (11) along an overall length of sampled region (Is) and the electrical connection of the photo detectors (14, 14', 14", 14"') with the electronic read out system is achieved by a multiplicity of printed electrical conductors (15).