Multiplexed photonic Doppler velocimetry enabled by multichannel optical switching: An optimization methodology for crosstalk suppression.

Abstract

Recent advancements in velocity measurement, leveraging the benefits of photonic Doppler velocimetry in the domains of shock and detonation physics, explosive safety, and materials physics, have led to the development of array or area velocity measurements for high-fidelity research. However, the direct superimposition of multiple PDVs can result in significant increases in volume, cost, and complexity. In recent years, multiplexed photonic Doppler velocimetry (MPDV) has emerged as an effective solution for measuring velocities at numerous points. While time-division multiplexed MPDV systems have gained attention for circumventing the bandwidth constraints inherent in frequency-division multiplexed approaches, the critical issue of optical crosstalk induced by optical switching components remains insufficiently addressed. Current commercial optical switches with limited isolation performance may introduce channel interference that compromises measurement accuracy in precision experiments. This study presents a novel time-division multiplexed MPDV architecture employing multichannel optical switching modules. Through precise timing control, eight distinct velocity signals with different delay times can be obtained from a single channel, enabling simultaneous recording of 64 velocity signals using two conventional four-channel digitizers. Furthermore, the crosstalk issue can be significantly mitigated through optimized optical switch configurations and probe design modifications. The method's validity has been experimentally verified through an experiment involving explosive-driven metal flyers. This method holds significant potential for further expanding the number of measurement points in MPDV applications.