Interleaved Aliased AWG Filter for Wideband Wavelength Discrimination
Solution Overview
Problem
Current wavelength interrogator architectures are limited by the number of discrete sine filters, restricting the deployment of fiber Bragg grating sensors, and existing technologies do not efficiently allow for simultaneous interrogation of multiple sensors without increasing the number of filters.
Innovation Solution
The use of arrayed waveguide grating (AWG) filters with aliasing responses, coupled with a circulator and broadband sources, allows for simultaneous interrogation of multiple fiber Bragg grating sensors by utilizing the skirt responses of adjacent AWG channels to determine the wavelength of each sensor, enabling the use of a single AWG to handle multiple sensor strings with unique wavelength ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete sine filters are used for wavelength discrimination, then wavelength resolution is achieved, but the number of sensors is limited by the number of filters
Solution Approach 1:
A single AWG filter is designed to perform wavelength discrimination across multiple wavelength ranges simultaneously. The filter uses aliasing responses where the lowest wavelength of the first AWG aliases to a wavelength greater than the highest wavelength of the second AWG, allowing one filter to serve multiple sensing functions that would traditionally require separate discrete sine filters
Solution Approach 2:
The patent transitions from a one-dimensional approach (single wavelength range per filter) to a multi-dimensional approach by utilizing aliasing responses that map different wavelength ranges to the same physical filter structure. This allows the AWG to resolve wavelengths across extended ranges by leveraging the aliasing relationship between different wavelength domains
2Adaptability or versatility
If multiple discrete sine filters are used to increase sensor capacity, then more sensors can be interrogated, but device complexity increases
Solution Approach 1:
Multiple wavelength ranges and sensor interrogation functions are merged into a single AWG filter structure. Instead of using separate discrete sine filters for different wavelength ranges, the patent combines these functions into one filter that handles multiple ranges through aliasing, thereby reducing the total number of filter components while maintaining the ability to interrogate multiple sensors
3Measurement precision
If individual sine filters tuned to particular wavelength ranges are used, then wavelength discrimination in specific ranges is achieved, but continuous wavelength coverage is limited
Solution Approach 1:
The AWG filter provides continuous wavelength coverage by ensuring that the aliasing response of the lowest wavelength channel is adjacent to the highest wavelength channel. This creates a continuous spectrum where wavelength discrimination can be performed across the entire range without gaps, eliminating the discontinuities that would exist with multiple separate tuned filters
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 the simultaneous interrogation of multiple sensors using a single AWG, overcoming the limitations of discrete filters and allowing for continuous wavelength coverage, thereby increasing the number of sensors that can be deployed without the need for multiple AWG filters.
Implementation Method 1
arrayed waveguide grating (AWG) filter with a response in a first wavelength range
Implementation Method 2
the lowest wavelength of the first AWG aliases to a wavelength greater than the highest wavelength of the second AWG filter
Implementation Method 3
the circulator transferring optical energy from the broadband source to a sensing optical fiber having a plurality of fiber Bragg gratings for sensing, reflected optical energy from the fiber gratings reflected back to the circulator
Implementation Method 4
a sensing optical fiber having a plurality of fiber Bragg gratings for sensing, each fiber grating operating in a unique wavelength range
Data Source
AI summary
A plurality of AWG filters with aliasing responses are selected such that the wavelength range of a fundamental response of the AWG filters results in the aliased range of AWG filters to be adjacent to a fundamental range of the AWG filters. A plurality of optical sources is provided sufficient to cover each fundamental wavelength range and each alias wavelength range of the AWG filters. When a single one of the optical sources is enabled, reflected optical energy from a series string of FBGs coupled to the optical source is applied to the plurality of AWG filters, and the AWG output in combination with the wavelength range of the optical source is used to discriminate reflected wavelength from the FBG sensors.