Waveguide Spectrometer Refractive Index Modulation
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Solution Overview
Problem
Current miniaturized waveguide spectrometers are limited by the fixed placement of interferogram samplers, which restricts their spectral bandwidth and makes them unsuitable for broadband applications, violating the Nyquist criterion and resulting in narrow-band devices only useful for single-pixel applications.
Innovation Solution
The integration of electrodes on the opposing side faces of the waveguide substrate layer allows for an electro-optical or thermal effect that varies the refractive index, enabling interferogram scanning within the waveguide without moving parts, thus expanding the spectral range and bandwidth by modulating the refractive index using an electric field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If interferogram samplers are fixed in place in a miniaturized waveguide spectrometer, then the device achieves compact size and miniaturization, but the spectral bandwidth is restricted and the device violates the Nyquist criterion for broadband applications
Solution Approach 1:
The patent applies the dynamics principle by making the refractive index of the waveguide dynamically adjustable through electro-optical or thermal effects. By applying voltage to electrodes or heating elements integrated into the waveguide substrate, the refractive index can be varied in real-time, enabling the fixed physical samplers to effectively sample different portions of the interferogram spectrum. This dynamic parameter adjustment allows the compact device to achieve broadband spectral coverage without requiring physical movement of components.
Solution Approach 2:
The patent implements parameter changes by modifying the refractive index of the waveguide material through external stimuli (electrical voltage or thermal energy). This parameter change enables the same physical sampler positions to correspond to different optical path differences at different times, effectively expanding the spectral bandwidth. The ability to tune the refractive index allows the device to satisfy the Nyquist criterion for broadband applications while maintaining miniaturized dimensions.
2Adaptability or versatility
If moving mirrors or additional building blocks are used to expand spectral range, then the spectral bandwidth increases, but the device complexity and size increase
Solution Approach 1:
The patent merges the functions of interferogram sampling and refractive index modulation into a single integrated waveguide structure. The electrodes or heating elements are directly integrated into the waveguide substrate, eliminating the need for separate moving mirror mechanisms or additional optical building blocks. This consolidation achieves broadband spectral range while maintaining device simplicity and compactness.
Solution Approach 2:
The patent replaces mechanical moving mirror systems with a field-based control mechanism. Instead of physically moving components to change the optical path difference, the invention uses electro-optical or thermal effects to modulate the refractive index, thereby achieving the same spectral expansion function without mechanical complexity. This substitution eliminates moving parts and reduces system complexity while maintaining the ability to scan the interferogram.
3Ease of manufacture
If fixed sampler placement is used in waveguide spectrometers, then manufacturing is simplified, but the device is limited to narrow-band applications only useful for single-pixel applications
Solution Approach 1:
The patent maintains the manufacturing simplicity of fixed sampler placement while overcoming the narrow-band limitation through parameter changes. The refractive index modulation capability allows the same manufactured device to be dynamically reconfigured for different spectral ranges. This approach preserves the ease of manufacture (fixed samplers) while dramatically expanding the application range to include broadband spectroscopy, multi-pixel imaging, and dynamic spectral analysis.
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 allows for a compact, broadband waveguide-based interferogram acquisition system suitable for dynamic Fourier Transform spectrometers, enabling extended or full-range interferogram sampling without additional building blocks, such as moving mirrors, thereby enhancing the spectral range and bandwidth.
Implementation Method 1
The integration of electrodes on the opposing side faces of the waveguide substrate layer allows for an electro-optical or thermal effect that varies the refractive index
Implementation Method 2
The integration of electrodes on the opposing side faces of the waveguide substrate layer allows for an electro-optical or thermal effect that varies the refractive index
Implementation Method 3
enabling interferogram scanning within the waveguide without moving parts, thus expanding the spectral range and bandwidth by modulating the refractive index using an electric field
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
The disclosed invention consists of a waveguide spectrometer (1), comprising at least one substrate layer (10) with at least one surface waveguide (11), each waveguide (11) is extending form an inlet face (12) and is configured to guide the received light, at least one evanescent field sampler in the waveguide (11), configured to out-couple light along the waveguide (11), at least one light sensing unit configured to detect the out-coupled light, each electrically connected to an electronic read out system, and a means to achieve counter propagating optical signals inside the waveguide (11) configured to obtain interference between the counter propagating optical signals generating an interference pattern along the waveguide (11), while the waveguide spectrometer (1) should have a compact and simple construction while improving the spectral range/bandwidth of the spectrometer. This is reached in that the Waveguide Spectrometer (1) comprises at least one modulator integrated into the sampling waveguide structure configured to enable conditioning of the guided optical signals and configured for changing the refractive index, wherein said at least one integrated modulator is realised by electrodes (30; 30') placed aside directly neighboured to the guiding core resp. waveguide (11) generating an optical phases shift required for scanning the interferogram.