Ultrafast Fiber Bragg Grating Interrogation for Sensing in Detonation and Shock Wave Experiments

Area of Science:

• High energy density physics
• Materials science
• Optical sensing technologies

Background:

• Shock wave and detonation phenomena require advanced diagnostic tools for accurate monitoring.
• Traditional methods often lack the speed and spatial resolution needed for dynamic events.
• Chirped Fiber Bragg Gratings (CFBGs) offer a promising avenue for high-fidelity measurements.

Purpose of the Study:

• To present Chirped Fiber Bragg Grating (CFBG) sensors and high-speed interrogation systems as robust diagnostics for shock wave and detonation front propagation.
• To demonstrate the capability of embedded CFBG systems for sensing shock and detonation-driven loading.
• To evaluate the performance of these systems across various dynamic tests.

Main Methods:

• Utilizing the linear distributed spatial encoding of the spectral band in single-mode CFBGs.
• Employing two photonic interrogation approaches: integrated spectrum analysis and coherent pulse interrogation.
• Achieving interrogation rates from 100 MHz to 1 GHz with spatial resolution from 50 µm to sub-millimeter.

Main Results:

• Demonstrated high-speed (100 MHz–1 GHz) interrogation rates for CFBG sensors.
• Achieved precise spatial resolution (50 µm to sub-millimeter) for tracking dynamic events.
• Successfully tracked linear detonation fronts in PBX-9501, radial decaying shocks, and shock waves in aluminum under varying loads.

Conclusions:

• CFBG sensors coupled with high-speed interrogation systems provide effective, robust diagnostics for shock physics.
• The described photonic methodologies enable precise spatial and temporal resolution of shock and detonation events.
• These systems are suitable for diverse applications, including tracking detonation propagation and shock wave dynamics in materials.