Tunable Broadband Light Source Using Diffraction Grating Multiplexing
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Solution Overview
Problem
Conventional broadband light sources with tunable spectrum are costly due to the need for separating, modulating, and recombining individual narrow bands of light, which increases operational expenses.
Innovation Solution
The use of multiplexing multiple light sources, such as LEDs, with thin-film filters or diffraction gratings to create a tunable spectrum, where a diffraction grating diffracts light beams into a slit-shaped aperture, allowing for wavelength selectivity based on the types and positions of light sources and grating properties, enabling the production of a composite broadband light signal with tunable spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple modulators are used to separate, modulate, and recombine narrow bands of light, then tunable spectrum is achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple light sources emitting different wavelengths into a single broadband light source, eliminating the need for separate modulators for each wavelength band. The merged light sources are directed through a diffraction grating that spatially separates wavelengths, allowing a single modulator to control the entire spectrum by modulating the intensity of light passing through different wavelength regions.
Solution Approach 2:
A single modulator is designed to perform the function of multiple modulators by controlling the intensity of light across the entire broadband spectrum. The modulator receives composite light from all wavelength regions and can independently control the intensity of each wavelength component, thereby achieving tunable spectrum output without requiring separate modulation stages for each wavelength band.
2Adaptability or versatility
If multiple modulators are used to separate and modulate individual narrow bands, then wavelength control is achieved, but operational cost increases
Solution Approach 1:
The patent merges multiple light sources into a single broadband source and uses a single modulator to control all wavelengths, thereby reducing the number of active components that consume power. The diffraction grating passively separates wavelengths without requiring additional energy input, and the single modulator efficiently controls the intensity of all wavelength components simultaneously.
Solution Approach 2:
The diffraction grating automatically performs wavelength separation based on the incident broadband light, without requiring external control or additional energy input. The spatial distribution of wavelengths created by the grating allows the single modulator to inherently control each wavelength region, eliminating the need for complex active wavelength selection mechanisms that would consume additional energy.
3Measurement precision
If broadband light is separated into individual narrow bands for modulation, then spectral resolution is improved, but light throughput decreases
Solution Approach 1:
The patent merges all wavelength components into a single broadband beam that passes through the modulator, maximizing light throughput. The diffraction grating then spatially separates the wavelengths after modulation, providing spectral resolution at the output stage rather than during modulation, thereby avoiding loss of light intensity that would occur with sequential narrow-band modulation.
Solution Approach 2:
The patent transitions from temporal or sequential wavelength selection to spatial wavelength separation. The diffraction grating disperses wavelengths in the spatial domain, creating a spatial spectrum where different wavelengths are positioned at different locations. This allows the modulator to control all wavelengths simultaneously while maintaining spectral resolution through spatial positioning at the output.
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 reduces costs and enhances spectral resolution and light throughput, allowing for high-tuning speed, typically exceeding tens of MHz, and provides flexible wavelength selection and intensity control, suitable for various applications.
Implementation Method 1
A diffraction grating diffracts light beams from the plurality of light sources to a slit-shaped aperture. Wavelength selectivity by the diffraction grating to the slit-shaped aperture depends on several combinational factors, including the types of selected light sources, the relative positions of the light sources to the slit-shaped aperture, and the type of grating
Implementation Method 2
The concave diffraction grating comprises one or more grooves etched to a surface to deflect and combine the plurality of wavelengths sent from the plurality of light sources to an output slit-shaped aperture
Implementation Method 3
A transmission diffraction grating diffracts and combines the plurality of light beams at an angle in substantially the same direction into combined light beams
Implementation Method 4
A first lens collimates the diverging rays from a plurality of light sources to generate collimated light beams
Implementation Method 5
The second lens focuses the combined light beams for transmission to the output slit-shaped aperture
Data Source
AI summary
Broadband light source systems, devices, and methods with a tunable spectrum are described by multiplexing a plurality of light sources, such as LEDs, with thin-film filters or diffraction gratings. A plurality of light sources with different or same wavelengths are multiplexed together to construct a combined broadband light source. A diffraction grating diffracts light beams from the plurality of light sources to a slit-shaped aperture, depending on selected light sources, the relative positions of the light sources to the slit-shaped aperture, and the type of grating to produce a tunable spectrum.