Dispersed Fourier Transform Spectrometer for High Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Fourier transform spectrometers face challenges in achieving high resolution and sensitivity due to trade-offs between resolution and signal-to-noise ratio, especially with broadband optical inputs, and on-chip implementations often result in reduced spectral bandwidth and sensitivity.
Innovation Solution
A dispersed Fourier transform spectrometer is developed, utilizing an interferometer with a controllable delay element and a dispersive element to generate multiple narrowband interferograms, which are analyzed by a detector array, enhancing spectral resolution and sensitivity by increasing the coherence length and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional Fourier transform spectrometer uses a broadband optical input to achieve broad spectral coverage, then the spectral bandwidth is improved, but the signal-to-noise ratio and resolution deteriorate due to reduced coherence length
Solution Approach 1:
The broadband spectrum is segmented into multiple narrowband spectral channels using a dispersive element (grating or prism). Each narrowband channel is then processed independently by the interferometer, maintaining high coherence length and signal-to-noise ratio while collectively covering the broad spectral range.
Solution Approach 2:
The patent transitions from temporal interference measurement to spatial-spectral interference measurement by introducing a dispersive element. Instead of measuring the entire broadband spectrum through a single temporal interferogram, the system creates multiple spatially separated narrowband interferograms, each with high coherence, and combines them to achieve broad spectral coverage with high resolution.
2Volume of moving object
If on-chip implementations of Fourier transform spectrometers are used to achieve miniaturization, then device portability is improved, but spectral bandwidth and sensitivity are reduced
Solution Approach 1:
The patent merges the interferometer and dispersive element onto a single integrated photonic chip. The interferometer arms, beam splitters, and dispersive grating are all fabricated using standard photonic integration techniques, achieving miniaturization while maintaining broad spectral bandwidth through the combined functionality of these integrated components.
Solution Approach 2:
The integrated chip design uses planar waveguides and spatial multiplexing to achieve functions that would otherwise require bulk optics. The dispersive element is implemented as a planar grating or arrayed waveguide grating on the chip, enabling broad spectral coverage in a miniaturized format.
3Measurement precision
If the delay path length in the interferometer is increased to improve spectral resolution, then resolution is improved, but the signal-to-noise ratio deteriorates due to loss and reduced coherence
Solution Approach 1:
Instead of using a single long delay path, the patent segments the spectral measurement into multiple narrowband channels. Each channel has its own interferometer path with optimized, shorter delay length, maintaining high signal-to-noise ratio while achieving high overall spectral resolution through the combination of multiple high-resolution narrowband measurements.
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
The solution provides high-resolution spectrometry with improved sensitivity over a broad spectral range, suitable for miniaturized and portable devices, addressing the limitations of existing on-chip spectrometers by generating high-SNR interferograms that can be combined for accurate spectral analysis.
Implementation Method 1
an interferometer generating an interferogram by splitting an interferometer input signal between a reference arm and a variable delay arm, and introducing a delay between the split interferometer input signals prior to interfering the split interferometer input signals
Implementation Method 2
the controllable delay element can adjust the refractive index of a portion of the variable delay arm to introduce the delay
Implementation Method 3
the controllable delay element can adjust the refractive index of a portion of the variable delay arm by changing the temperature of the variable delay arm
Implementation Method 4
a dispersive element outputting a plurality of narrowband outputs representative of a received broadband input signal
Data Source
AI summary
A spectrometer is provided, the spectrometer having an interferometer generating an interferogram by splitting an interferometer input signal between a reference arm and a variable delay arm, and introducing a delay between the split interferometer input signals prior to interfering the split interferometer input signals. The spectrometer additionally has a controllable delay element operable to adjust the delay introduced by the interferometer and a dispersive element outputting a plurality of narrowband outputs representative of a received broadband input signal. The interferometer and dispersive element are optically connected to output a plurality of narrowband interferograms representative of a spectra of a spectrometer input signal received by the spectrometer, and the plurality of narrowband interferograms are received by a detector array for analysis.