Terahertz Wave Generation via Cherenkov Phase Matching

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Solution Overview

Problem

The existing broadband terahertz generation methods using Cherenkov radiation face inefficiencies due to high absorption of terahertz waves by the LN substrate, limiting the output power of terahertz waves.

Innovation Solution

An electromagnetic wave emission device is designed with a nonlinear crystal and a total reflection layer, where the nonlinear crystal receives exciting light and outputs terahertz waves through Cherenkov phase matching, and the total reflection layer totally reflects these waves to prevent absorption, enhancing output power by optimizing the thickness and refractive indices of the components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If terahertz waves are generated using Cherenkov radiation in a nonlinear crystal on an LN substrate, then broadband terahertz generation is achieved, but the terahertz waves traveling toward the LN substrate are absorbed and attenuated, reducing output power

Engineering Contradiction:

Improveoutput power of terahertz wavesVSAvoidabsorption of terahertz waves by LN substrate

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

A low-refractive-index layer is introduced as an intermediary between the nonlinear crystal and the LN substrate. This intermediary layer has a refractive index lower than both the nonlinear crystal and the LN substrate, creating optical conditions that prevent total internal reflection and reduce absorption of terahertz waves by the substrate, thereby increasing output power

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter is strategically modified by introducing a low-refractive-index layer with specific optical properties. This parameter change alters the optical path and reflection characteristics at the interfaces, enabling terahertz waves to escape the nonlinear crystal without being absorbed by the LN substrate

Inventive Principle:

Principle #35Parameter changes

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 effectively increases the output power of terahertz waves by preventing absorption and ensuring efficient transmission, achieving approximately twice the power compared to conventional methods.

Implementation Method 1

a nonlinear crystal that receives exciting light having at least two wavelength components, and outputs an electromagnetic wave having a frequency equal to or more than 0.01 [THz] and equal to or less than 100 [THz] by means of the Cherenkov phase matching

Methodology Applied

Scientific EffectCherenkov phase matching: Cherenkov Effect

Implementation Method 2

a total reflection layer that is in contact with the nonlinear crystal, and totally reflects the electromagnetic wave output from the nonlinear crystal

Methodology Applied

Scientific EffectTotal reflection: Reflection

Data Source

PatentUS9228698B2Terahertz wave generating device which outputs a terahertz frequency electromagnetic wave via Cherenkov phase matching

Publication Date: 2016.01.05 ADVANTEST CORP

AI summary

An electromagnetic wave emission device includes a nonlinear crystal which receives exciting light Lp having two wavelength components λ1 and λ2, and outputs terahertz waves L1-L6, a total reflection layer which is in contact with the nonlinear crystal, and totally reflects the terahertz waves L2, L4, and L6 output from the nonlinear crystal, a substrate which mounts the total reflection layer, and top clads which are placed on an opposing surface of the nonlinear crystal, and transmit the terahertz waves L1-L6.