Optical Source Characterization Using Fixed Fabry-Perot Standards
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Solution Overview
Problem
Existing methods for characterizing optical sources, such as wavelength measurement, are either expensive due to the need for costly materials like InGaAs or PbSe for wavelengths beyond 1100 nm, or slow due to mechanical movement in tunable Fabry-Perot configurations, limiting their robustness and efficiency.
Innovation Solution
A method and device using a system with multiple Fabry-Perot standards without moving parts, where each sensor includes a photodiode and a Fabry-Perot with a transmission curve, forming an overall transmission curve to select wavelengths within a spectral zone, allowing for faster and more economical characterization by eliminating values outside the spectral zone interval using a least squares method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photodiode arrays are used for wavelength exploration, then measurement coverage is improved, but cost increases significantly
Solution Approach 1:
The spectral exploration function is segmented across multiple fixed Fabry-Perot interferometers, each tuned to a specific wavelength range. Instead of using a single expensive photodiode array that covers the entire spectrum, the system divides the spectral measurement task into multiple specialized interferometers operating at fixed wavelengths, reducing the need for expensive broadband detection materials.
Solution Approach 2:
Fixed Fabry-Perot interferometers serve as intermediary devices between the optical source and the photodiode detectors. These interferometers filter and select specific wavelength components before they reach the photodiodes, enabling the use of simpler, less expensive photodiode materials while maintaining comprehensive spectral coverage through multiple intermediate filtering stages.
2Measurement precision
If tunable Fabry-Perot with moving parts is used, then measurement precision is improved, but measurement speed decreases
Solution Approach 1:
Instead of using a single tunable Fabry-Perot interferometer with moving parts that scans through wavelengths sequentially, the invention inverts the approach by using multiple fixed Fabry-Perot interferometers with predetermined wavelengths. This eliminates the need for mechanical scanning while maintaining the ability to measure across a broad spectral range, thereby improving measurement speed without sacrificing precision.
Solution Approach 2:
The mechanical scanning system of a tunable Fabry-Perot interferometer is replaced with a static array of multiple fixed Fabry-Perot interferometers. This substitution eliminates moving mechanical parts, removing the speed limitation imposed by sequential scanning while preserving the high precision wavelength measurement capability through parallel detection at multiple fixed wavelength points.
3Ease of manufacture
If silicon photodiodes are used, then cost is reduced, but wavelength measurement capability is limited to below 1100 nm
Solution Approach 1:
The wavelength measurement task is segmented into multiple fixed spectral bands, each handled by a dedicated Fabry-Perot interferometer. This segmentation allows the use of silicon photodiodes for each band, as each interferometer filters the incoming light to only the specific wavelength range that silicon can detect, effectively extending the overall system's wavelength capability beyond what a single silicon photodiode could achieve alone.
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 faster and more economical characterization of optical sources by eliminating the need for expensive materials and mechanical movement, achieving high precision and speed in wavelength measurement.
Implementation Method 1
each sensor (4) comprising a Fabry Perot standard (5) followed by a photodiode (6), each Fabry Perot standard having a transmission curve of the intensity of the first radiation, as a function of the wavelength of the first radiation
Implementation Method 2
each sensor (4) comprising a Fabry Perot standard (5) followed by a photodiode (6)
Data Source
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AI summary
The present invention relates to a process for characterising an optical source (1) comprising a fixed cavity (2) having a free spectral range, said process comprising: - generating a first radiation (3); receiving at least a portion of this first radiation by at least one sensor (4); measuring a signal by each sensor and for each scanned state of the source; on the basis of the signals measured, and for each scanned state of the source, calculating a first data item which represents the wavelength of the first radiation, the calculation comprising, for each scanned state of the source, a selection of a selected value of the first data item from a plurality of possible values, said selection comprising the elimination of the values of the first data item which do not correspond to a modulo constant of the free spectral range of the fixed cavity expressed according to the units of the first data item.