RPI ID: 
2010-061-402

Innovation Summary:
This invention enables true stand-off detection of terahertz (THz) radiation by converting THz–plasma interactions into detectable acoustic emissions. A femtosecond optical beam (single- or dual-color) is focused in air to create a laser-induced plasma that, under incident radiation (preferably THz, but extendable from RF to X-ray), produces an enhanced far-field acoustic signal after the initial shock front relaxes. In a two-plasma configuration, an emitter plasma generates THz directed at a target, while a spatially separated sensor plasma converts the target-scattered/ transmitted THz into an omni-directional sonic/ultrasonic pulse that is recorded acoustically—no electrodes or cabling at the remote site. Temporal delay control between dual-color pulses tunes generation/detection, supporting remote, meter-to-tens-of-meters operation for hazardous-material ID, non-invasive imaging, and other security, biological, and industrial sensing tasks.

Challenges / Opportunities:
Remote THz sensing is fundamentally constrained by strong atmospheric water-vapor attenuation and by detection schemes that require on-site electrodes or probes, limiting range and practicality; as a result, “true” coherent, stand-off THz detection has remained elusive despite progress in optical THz generation. This invention solves those limitations by bridging THz photonics and photoacoustics: the THz field perturbs a laser-induced plasma and is encoded as a robust acoustic emission that can be detected at a distance, eliminating local electronics at the interrogation site and reducing the effective THz free-space path. The configurable single/dual-color femtosecond pumping, adjustable time delay, and separate emitter/sensor plasmas provide tunable sensitivity and geometry, enabling safer explosives/chemical threat sensing, remote materials analysis, and field-deployable systems with simpler hardware, wider environmental tolerance, and scalable coverage.

Key Benefits / Advantages:
✔ Enables remote terahertz detection
✔ Converts terahertz signals into acoustic emissions
✔ Overcomes atmospheric attenuation limits
✔ Broad defense and security applications

Applications:
• Standoff detection of explosives
• Border and airport security
• Remote sensing of hazardous substances
• Industrial and biomedical imaging

Keywords:
THz acoustic plasma detection; laser-induced plasma; dual-color femtosecond pulses; stand-off sensing; emitter/sensor plasmas; single-cycle THz; acoustic emission enhancement; remote hazard detection.

Intellectual Property:
Issued US Patent No.  9,110,022 B2