Terahertz Waveguide With Reflecting Layer
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Solution Overview
Problem
Existing methods for generating terahertz waves using nonlinear optical crystals suffer from limited extraction efficiency, as only half of the generated waves can be extracted, with the rest being absorbed, and lack effective control over waveform shaping.
Innovation Solution
A terahertz wave generation element featuring an optical waveguide with an electro-optic crystal core, an optical coupler for extracting terahertz waves, and a reflecting layer to reflect and enhance the extraction of terahertz waves, allowing for flexible control over waveform shaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a nonlinear optical crystal is used to generate terahertz waves, then terahertz waves can be generated, but only half of the generated waves can be extracted while the rest are absorbed
Solution Approach 1:
The invention segments the terahertz wave generation and extraction process by introducing a reflecting layer that directs terahertz waves toward the extraction surface. This segmentation allows separate optimization of generation (in the bulk crystal) and extraction (at the surface), resolving the contradiction by ensuring generated waves are systematically directed for extraction rather than being randomly absorbed.
Solution Approach 2:
The invention adds a spatial dimension to terahertz wave extraction by introducing a reflecting layer at a specific depth within the crystal. This creates a three-dimensional extraction pathway where terahertz waves generated throughout the crystal volume can be reflected and channeled to the extraction surface, effectively utilizing the depth dimension to improve extraction efficiency beyond the conventional surface-only approach.
2Adaptability or versatility
If conventional methods are used for terahertz wave generation, then terahertz waves can be generated, but waveform shaping control is limited
Solution Approach 1:
The invention applies preliminary action by pre-configuring the reflecting layer at a specific depth within the crystal before terahertz wave generation occurs. This pre-arranged reflective structure automatically shapes the waveform as terahertz waves are generated and reflected, providing waveform shaping control without requiring complex real-time adjustments or additional control mechanisms during operation.
3Illumination intensity
If high intensity terahertz waves are generated, then signal strength improves, but pulse width increases
Solution Approach 1:
The invention utilizes the depth dimension within the crystal by positioning the reflecting layer at a specific depth. This allows terahertz waves to be generated throughout the crystal volume and reflected to the extraction surface, maintaining high intensity through increased generation volume while the controlled reflection path preserves narrow pulse width by avoiding excessive propagation distance and dispersion.
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 configuration enables efficient generation of high-intensity terahertz waves with narrow pulse widths and improved extraction efficiency, enhancing the performance of terahertz time domain spectroscope devices by controlling the waveform and increasing depth resolution in tomography.
Implementation Method 1
there are known a method of generating a single color terahertz wave by an optical parametric process and a method of generating a terahertz pulse by optical rectification with irradiation of a femtosecond pulse laser beam
Implementation Method 2
there are known a difference-frequency generation (DFG) using incidence of two laser beams having a frequency difference
Implementation Method 3
an electrooptic Cerenkov radiation has been noted recently. This is a phenomenon in which, as illustrated in FIG. 9, a terahertz wave 101 is radiated in a conical manner like a shock wave in a case where a propagation group velocity of a laser beam 100 as an excitation source is faster than a propagation phase velocity of the generated terahertz wave
Implementation Method 4
a reflecting layer 6 for reflecting the generated terahertz wave is formed between the waveguide core 4 and the lower clad 2
Data Source
AI summary
A terahertz wave generation element is provided, which includes: an optical waveguide including a core of electro-optic crystal; an optical coupler for extracting a terahertz wave generated from the optical waveguide when light propagates in the optical waveguide to a space; and a reflecting layer disposed on the opposite side to the optical coupler with respect to the core of the optical waveguide, so as to reflect the generated terahertz wave. According to the element, it is possible to provide a generation element that can generate a relatively high intensity terahertz wave efficiently by photoexcitation or generate a terahertz wave having a relatively narrow pulse width, so as to flexibly control waveform shaping of the generated terahertz wave.