Divided Prism Wave Plate for Terahertz Phase Control
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Solution Overview
Problem
Conventional wave plates using refractive index anisotropy are limited in wavelength region due to inverse proportional phase change, and Fresnel rhomb type wave plates become cumbersome with large beam diameters, requiring multiple wave plates for terahertz waves and increased size.
Innovation Solution
A wave plate utilizing total reflection with a divided prism member, where each waveguide region has partial entrance and exit surfaces and multiple total reflection surfaces, allowing for phase change independent of wavelength and enabling downsizing by adjusting the inclination angles and stacking according to beam diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wave plate using refractive index anisotropy is used, then phase change can be achieved, but the wavelength region is limited due to inverse proportional phase change
Solution Approach 1:
The invention changes the fundamental parameter for achieving phase change from refractive index anisotropy to total reflection. By using total reflection, the phase change becomes independent of wavelength, allowing the wave plate to operate across a wide wavelength region including terahertz waves, while maintaining consistent phase change characteristics.
2Area of stationary object
If the entrance surface of the prism is enlarged to apply to light having a large beam diameter, then the wave plate can handle larger beams, but the size of the prism in the traveling direction becomes large and cumbersome
Solution Approach 1:
The invention divides the prism into multiple waveguide regions stacked in the traveling direction of light. Each waveguide region has a partial entrance surface, and by stacking multiple regions, the total entrance surface area is enlarged to accommodate large beam diameters while keeping the length of each individual waveguide region compact, thus avoiding a cumbersome overall prism size.
3Manufacturing precision
If multiple wave plates are prepared for different wavelengths, then each wavelength can be optimized, but the device complexity and handling difficulty increase
Solution Approach 1:
The invention creates a universal wave plate using total reflection that can handle multiple wavelength regions including terahertz waves with a single device. The wave plate structure with stacked waveguide regions provides wavelength-independent phase change, eliminating the need for multiple separate wave plates for different wavelengths, thus reducing device complexity and handling difficulty.
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
Enables phase change over a wide wavelength region with reduced size, preventing interference and maintaining accurate phase control, facilitating easy handling and adjustment in optical systems.
Implementation Method 1
phase of the terahertz wave is changed through the use of total reflection
Implementation Method 2
a gap portion with a space larger than a leaking depth of the evanescent wave of the terahertz wave
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3
AI summary
A wave plate 1 comprising: a prism member 2 having an entrance surface 3 for receiving a terahertz wave T, and an exit surface 4 for emitting the terahertz wave T received by the entrance surface 3; wherein the prism member 2 is constituted by a plurality of waveguide regions having: a partial entrance surface 13 for receiving a part of the terahertz wave T, a plurality of total reflection surfaces 15 for totally reflecting the terahertz wave T from the partial entrance surface 13, and a partial exit surface 14 for emitting the terahertz wave T totally reflected from the total reflection surfaces 15; and each of the partial entrance surfaces 13 combine to constitute the entrance surface 3 of the prism member 2, and each of the partial exit surfaces 14 combine to constitute the exit surface 4 of the prism member 2, by stacking waveguide regions.