Wavelength Reference with Unique Spectral Notch for Peak Ambiguity
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Solution Overview
Problem
Existing wavelength reference devices using Fabry-Perot etalons face challenges in accurately identifying wavelength peaks due to their repeating spectral responses, leading to potential misadjustments in wavelength-sensitive equipment, especially when frequency differences exceed 0.5*ΔF, resulting in incorrect frequency shifts.
Innovation Solution
A wavelength reference device comprising a broadband optical source, a repeating filter (such as a Fabry-Perot etalon), and a wavelength-specific filter (like a notch filter) is used to generate a wavelength reference signal with attenuated predefined wavelength responses, providing unique spectral features to resolve ambiguity and ensure accurate wavelength calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a repeating filter (Fabry-Perot etalon) is used to provide wavelength reference, then information across the wavelength band is provided, but location ambiguity occurs making it difficult to resolve frequency differences greater than 0.5*ΔF
Solution Approach 1:
The patent divides the repeating spectral response into segments by introducing a wavelength-specific feature (notch) that segments the otherwise identical repeating peaks. This segmentation allows the system to distinguish between different wavelength regions while maintaining the broadband information provided by the repeating response.
Solution Approach 2:
The patent applies local quality by introducing a wavelength-specific notch filter that creates a unique local feature (attenuated wavelength) within the broader repeating spectral pattern. This local modification provides a reference point for absolute wavelength identification without affecting the overall repeating structure that provides broadband coverage.
2Adaptability or versatility
If a repeating spectral response is used, then broadband wavelength coverage is achieved, but neighboring peaks may be incorrectly identified leading to wrong wavelength adjustment
Solution Approach 1:
The patent introduces asymmetry into the otherwise symmetric repeating spectral pattern by adding a wavelength-specific notch that breaks the symmetry. This asymmetric feature creates a unique identifier for each wavelength region, allowing the system to maintain broadband coverage while reliably identifying the correct wavelength location.
Solution Approach 2:
The wavelength-specific notch filter acts as an intermediary element that mediates between the repeating filter's broadband response and the wavelength-sensitive equipment's identification needs. It provides a reference signal that bridges the gap between the repeating pattern and absolute wavelength determination.
3Measurement precision
If the starting frequency shift exceeds 0.5*ΔF, then frequency accuracy degrades, but the repeating spectral response cannot provide additional information to correct the error
Solution Approach 1:
The patent applies preliminary action by pre-introducing a wavelength-specific notch feature into the spectral response before the wavelength measurement process begins. This preliminary modification provides a known reference point that enables the system to correct frequency shifts and identify the correct wavelength region even when initial frequency accuracy is poor.
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 device enhances the ability of wavelength-sensitive equipment to resolve frequency differences across the entire optical wavelength band, reducing location ambiguity and ensuring precise wavelength calibration by incorporating a unique spectral feature that can be identified by the equipment.
Implementation Method 1
a broadband optical source 52 configured to emit optical power 53 along an optical path 51
Implementation Method 2
a repeating filter 54 positioned in the optical path and configured to filter the optical power 53 into a repeating spectral response
Implementation Method 3
a wavelength-specific filter 56 positioned in the optical path and configured to attenuate the optical power of at least one predefined wavelength response
Data Source
AI summary
A wavelength reference device includes a broadband optical source, a repeating filter, and a wavelength-specific filter. The source, which can be a super-luminescent light-emitting diode (SLED), emits optical power. The repeating filter, which can be a Fabray-Perot etalon, filters the optical power into a repeating spectral response, and the wavelength-specific filter attenuates the optical power of at least one predefined wavelength response within the wavelength band. The repeating filter and the wavelength-specific filter output a wavelength reference signal having the repeating spectral response attenuated at the at least one predefined wavelength response. The predefined wavelength response reduces the ambiguity that can occur in the repeating frequency locations found in the repeating spectral response. In this way, an absolute wavelength reference is intrinsically provided in the wavelength reference that removes the location ambiguity caused by the repeating spectral response.