Grooved Backside Acoustic Termination for Batch Processing
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Solution Overview
Problem
Acousto-optic devices face challenges in achieving effective acoustic termination without interfering with the acoustic wave generated by the transducer, particularly in high-volume production, as existing methods require individual handling and complex processing steps, leading to inefficiencies and device damage.
Innovation Solution
Incorporating grooves on the backside of the device during early fabrication, allowing for batch processing and eliminating the need for separate device handling, with the grooves effectively dispersing the acoustic wave and reducing reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compound angle is ground on the backside to achieve effective acoustic termination, then acoustic wave reflection is reduced, but device complexity and processing time increase due to individual handling requirements
Solution Approach 1:
The backside surface is segmented into multiple grooves rather than using a single angled surface. These grooves are oriented at specific angles (e.g., 45 degrees) relative to the optical axis and are designed to scatter acoustic waves effectively. The groove structure divides the acoustic termination function across multiple geometric features, achieving the same acoustic termination effectiveness as compound angle grinding but with simpler, more manufacturable geometry that can be processed in batch.
2Reliability
If compound angle grinding is performed on each device individually, then acoustic interference is minimized, but productivity decreases due to separate handling and mounting requirements
Solution Approach 1:
The acoustic termination function is merged into the bulk substrate structure through grooves that are formed as an integral part of the crystal growth or early fabrication process. This eliminates the need for separate post-processing steps where individual devices would be mounted and ground. The groove structure is created in the bulk material before device assembly, allowing multiple devices to be processed simultaneously in batch without requiring individual handling or custom mounting fixtures for each device.
3Reliability
If a rougher backside surface is used to scatter acoustic waves, then acoustic termination improves, but substrate cracking and chipping increase
Solution Approach 1:
The groove structure provides localized geometric features that scatter acoustic waves without requiring the entire backside surface to be roughened. The grooves are positioned at specific locations and orientations where acoustic wave scattering is most effective, while the rest of the substrate surface remains smooth and intact. This localized approach achieves the necessary acoustic termination while preserving the mechanical strength and integrity of the substrate, avoiding the cracking and chipping that would result from extensive surface roughening.
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
The grooved backside design achieves significant acoustic wave attenuation, with attenuation levels of -40 to -46 dB, simplifying the processing and increasing device yield by avoiding complex angle grinding and individual handling, while maintaining device performance.
Implementation Method 1
the grooves effectively dispersing the acoustic wave and reducing reflections
Implementation Method 2
The grooved backside design achieves significant acoustic wave attenuation, with attenuation levels of -40 to -46 dB
Data Source
AI summary
An acousto-optic device having at least one groove on the backside improves acoustic termination of the device. The grooves can be added early in device fabrication and are compatible with batch processing, thereby avoiding the separate device handling. Grooving can be performed on the cell, before it is mounted to a batch plate. This simplifies batch plate processing by using a backside that remains parallel to the bondface.