Multimode Interference Coupler for Wavelength Shift Measurement
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Solution Overview
Problem
Existing wavelength shift measurement devices in optical fibers with Bragg grating reflectors suffer from low signal-to-noise ratio due to inefficient light collection in spectral regions with low amplitude responses.
Innovation Solution
Incorporating a multimode interference coupler between the arrayed-waveguide-grating demultiplexer and output waveguides to distribute the optical signal, resulting in flattened spectral responses and improved signal collection across two output channels for each sensor, enhancing the signal-to-noise ratio for wavelength shift measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a direct connection is used between the arrayed-waveguide-grating demultiplexer and output waveguides, then the device complexity is reduced, but the signal-to-noise ratio deteriorates due to inefficient light collection in spectral regions with low amplitude responses
Solution Approach 1:
A multimode interference coupler is introduced as an intermediary component between the arrayed-waveguide-grating demultiplexer and the output waveguides. This coupler redistributes the optical signal to multiple output channels, improving light collection efficiency in spectral regions with low amplitude responses and thereby enhancing the signal-to-noise ratio without excessive complexity increase
Solution Approach 2:
The optical signal is segmented and distributed to multiple output channels through the multimode interference coupler. Each output channel receives a portion of the distributed signal, allowing for improved signal collection across different spectral regions and enhancing overall measurement reliability
2Measurement precision
If the spectral responses are concentrated in narrow bands, then the wavelength shift measurement precision is improved, but the signal collection efficiency deteriorates in spectral regions with low amplitude responses
Solution Approach 1:
The signal distribution is extended from a single output channel to multiple output channels in the spatial dimension. The multimode interference coupler distributes the optical signal across multiple channels, each with flattened spectral responses, thereby increasing the total collected signal quantity while maintaining measurement precision through the distributed measurement approach
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 significantly improves the signal-to-noise ratio for wavelength shift measurements by redistributing energy to output channels with more spread spectral responses, allowing for more effective collection of signal wavelengths and reduced variations in wavelength shifts, thereby enhancing measurement accuracy.
Implementation Method 1
a multimode interference coupler being located between the arrayed-waveguide-grating demultiplexer and the two output waveguides. The multimode interference coupler is configured to distribute, to said two output waveguides, an optical signal originating from the arrayed-waveguide-grating demultiplexer
Implementation Method 2
an arrayed-waveguide-grating demultiplexer configured to spatially separate the spectral contributions of an input optical signal
Implementation Method 3
optical fibres within which reflectors of the Bragg grating type are inscribed, each reflecting light at a respective wavelength
Data Source
AI summary
A signal-distributing device that includes an arrayed-waveguide-grating demultiplexer and at least one receiving module. Each receiving module includes a multimode interference coupler and two output waveguides, the multimode interference coupler being located between the arrayed-waveguide-grating demultiplexer and the two output waveguides. The multimode interference coupler is configured to distribute, to the two output waveguides, an optical signal delivered by the arrayed-waveguide-grating demultiplexer. Such a device allows wavelength shifts in the signal delivered by a set of one or more sensors, in particular Bragg grating reflectors inscribed in a given optical fibre, to be measured. It allows a wavelength shift to be measured with a high linearity and a signal-to-noise ratio.