Terahertz Wave Generator Using Nonlinear Crystal Reflection
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Solution Overview
Problem
Conventional terahertz wave generators using laser beams with single wavelengths produce terahertz waves with narrowed spectral widths, limiting their ability to generate waves with a wide wavelength band, which restricts their application in testing and spectral analysis.
Innovation Solution
A terahertz wave generator employing a nonlinear crystal with a reflection optical system and wavelength selecting means, allowing the pumping beam and idler wave to re-enter and interact, generating terahertz waves with a wide wavelength band by using a convex lens or spherical-shaped reflection mirror, and selectively passing specific wavelengths to produce terahertz waves with large output and varied wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam with a single wavelength is used for the pumping beam and the seed beam, then the terahertz wave can be generated with a narrowed spectral width, but the terahertz wave cannot be generated with a wide wavelength band
Solution Approach 1:
The invention divides the single-wavelength laser beam into multiple wavelength components using a diffraction grating, creating multiple seed beams with different wavelengths. This segmentation allows the system to generate terahertz waves across a wide wavelength band while maintaining controlled spectral characteristics through the selective use of wavelength components.
Solution Approach 2:
The invention changes the wavelength parameter of the seed beam from a single fixed value to multiple discrete wavelength values by using a diffraction grating to separate the laser beam into its spectral components. This parameter change enables the generation of terahertz waves with a wide wavelength band while maintaining narrow spectral width through selective interaction.
2Power
If the pumping beam and seed beam enter the nonlinear crystal from opposite ends, then the terahertz wave can be generated with a large peak output, but the spectral width remains narrowed
Solution Approach 1:
The invention segments the seed beam into multiple wavelength components that enter the nonlinear crystal simultaneously from the same end as the pumping beam. This segmentation approach maintains the high peak output power through coherent interaction while expanding the spectral width by incorporating multiple wavelength components in the terahertz wave generation process.
Solution Approach 2:
The invention merges multiple wavelength components of the seed beam with the pumping beam in the nonlinear crystal, allowing simultaneous interaction of multiple wavelengths. This merging enables the generation of terahertz waves with both large peak output and wide spectral width, resolving the contradiction between power and spectral breadth.
3Adaptability or versatility
If multiple wavelengths are used in the seed beam, then the terahertz wave can be generated with a wide wavelength band, but the output power decreases
Solution Approach 1:
The invention performs preliminary action by using a diffraction grating to separate the laser beam into multiple wavelength components before they enter the nonlinear crystal. This preliminary spectral separation allows for optimized control of the interaction process, maintaining high output power while achieving wide wavelength band coverage through selective wavelength interaction.
Solution Approach 2:
The invention changes the wavelength parameter distribution in the seed beam from a single value to a controlled distribution of multiple values. By carefully controlling which wavelength components interact with the pumping beam in the nonlinear crystal, the system maintains high output power while achieving wide wavelength band coverage in the generated terahertz waves.
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
Facilitates the generation of terahertz waves with a wide wavelength band, enabling simultaneous testing of components and simplifying spectral analysis by omitting the need for separate wavelength separation, while allowing for selective generation of specific wavelengths.
Implementation Method 1
a nonlinear crystal for generating a terahertz wave by a parametric effect when a seed beam and a pumping beam enter
Implementation Method 2
a convex lens disposed between the reflection mirror and the other end surface of the nonlinear crystal, and the convex lens is disposed by being separated from the other end surface of the nonlinear crystal only by a focal distance of the convex lens
Implementation Method 3
a reflection optical system for allowing the pumping beam emitted from the other end surface of the nonlinear crystal to be reflected and to re-enter the other end surface
Data Source
AI summary
A pumping beam L1 enters from a pumping beam projector 3 into one end surface 2a of a nonlinear crystal 2, the pumping beam L1 and idler wave L2 are generated from another end surface 2b of the nonlinear crystal 2. The pumping beam L1 emitted from the other end surface 2b of the nonlinear crystal 2 is reflected and re-enters as a pumping beam L′ into the other end surface 2b and the idler wave L2 generated from the other end surface 2b of the nonlinear crystal is reflected by the reflection optical system 6 and re-enters as a seed beam L2′ into the other end surface 2b. The idler wave L2 enters as the seed beam L2′ together with the pumping beam L1′ into the nonlinear crystal and thus a terahertz wave with a large output and including a plurality of wavelengths can be generated.