IDT Acoustic Wave Layout for Second Harmonic Excitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acoustic wave devices face challenges in effectively exciting second harmonic waves while suppressing fundamental waves, due to low electromechanical coupling coefficients and the fundamental wave becoming an unnecessary wave when operating at high frequencies.
Innovation Solution
The acoustic wave device incorporates a piezoelectric substrate with a piezoelectric layer having regions with alternating polarization directions, where the first region and second region are positioned in the intersection region, allowing for the excitation of second harmonic waves and suppression of fundamental waves by alternating the polarization directions of the electrode fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the acoustic wave device operates at high frequency, then the operating frequency is improved, but the electromechanical coupling coefficient of the fundamental wave becomes small making it difficult to excite harmonic waves
Solution Approach 1:
The piezoelectric layer is divided into first and second regions with different polarization directions. This local differentiation of polarization properties enables selective excitation of harmonic waves while suppressing fundamental waves, resolving the contradiction between high operating frequency and sufficient electromechanical coupling coefficient
Solution Approach 2:
The invention changes the polarization direction parameter of the piezoelectric layer from uniform to alternating between first and second regions. This parameter change enables the device to operate at high frequencies while maintaining adequate electromechanical coupling for harmonic wave excitation
2Speed
If the second harmonic wave is used for operation, then the operating frequency is improved, but the fundamental wave becomes an unnecessary wave that must be suppressed
Solution Approach 1:
By creating first and second regions with different polarization directions in the piezoelectric layer, the invention enables selective wave excitation. The alternating polarization causes the fundamental wave to be suppressed while the second harmonic wave is enhanced, eliminating the harmful fundamental wave interference at high operating frequencies
Solution Approach 2:
The invention converts the typically harmful fundamental wave into a suppressed component by using alternating polarization regions. The polarization structure is designed so that the fundamental wave experiences destructive interference while the second harmonic wave experiences constructive interference, turning the fundamental wave from a harmful factor into a controlled element
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 the efficient excitation of second harmonic waves and effective suppression of fundamental waves, allowing for high-frequency operation with reduced unnecessary wave interference.
Implementation Method 1
a piezoelectric substrate including a piezoelectric layer, and an IDT electrode provided on the piezoelectric layer
Implementation Method 2
it is possible to provide acoustic wave devices that each excite a second harmonic wave and suppress a fundamental wave
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate including a piezoelectric layer, and an IDT electrode on the piezoelectric layer and including first and second electrode fingers interdigitated with each other and coupled to mutually different potentials. A portion of the piezoelectric layer where the IDT electrode is provided includes an intersection region. When a direction in which the first electrode fingers and the second electrode fingers extend is an electrode finger extending direction, a direction orthogonal to the electrode finger extending direction is an electrode finger orthogonal direction, and the IDT electrode is viewed in the electrode finger orthogonal direction, a region where the first electrode finger and the second electrode finger, which are adjacent to each other, overlap each other is the intersection region. The piezoelectric layer includes a first region and a second region having a polarization direction different from that of the first region.