Suppression of Brillouin oscillation in transparent free-standing diamond thin films in picosecond ultrasound

TL;DR

This paper demonstrates a method to suppress Brillouin oscillations in transparent diamond films by metallic coating, enabling clearer ultrasonics signals for sensor applications.

Contribution

The authors introduce a novel technique of metallic coating on both sides of free-standing diamond films to suppress Brillouin oscillations in picosecond ultrasonics.

Findings

Suppression of Brillouin oscillation in coated diamond films.

Enhanced clarity of ultrasonics signals for sensing.

Potential for improved sensor device performance.

Abstract

Brillouin oscillation appears in picosecond ultrasonics for a transparent specimen because of backward light scattering by moving strain pulse. Its amplitude is comparable with those of other responses, such as pulse-echo signals and through-thickness resonance, obscuring these non-Brillouin-oscillation responses. We here find that Brillouin oscillation can be suppressed in a transparent free-standing film by coating both sides with metallic thin film of appropriate thickness and that this peculiar behavior is caused by strain pulses generated on both sides with a slight phase difference. This phenomenon allowed us to fabricate a Brillouin-oscillation-free diamond free-standing film, which showed high capability for sensor applications.