Enhancing Sensitivity of Electric-Field Detection*

From selectively targeting cancer cells to accelerating healing processes, precise control and understanding of cold plasma properties are essential in medical contexts. Electric fields play a crucial role in modulating redox-based production pathways and necessitate accurate diagnostics. To address this need, we propose the utilization of Electric-Field Induced Second Harmonic (E-FISH), a well-established non-perturbative technique for measuring the amplitude of electric fields in cold atmospheric plasma. While E-FISH offers tunable time resolution, it falls short in terms of spatial resolution, measurement of the polarization of the electric field, and sensitivity for lower electric field regimes. Previous studies have explored methods such as homodyne amplification to enhance signal strength and spatial resolution [1, 2], yet these efforts are hindered by optomechanical variations, leading to a limited signal-to-noise ratio. Therefore, we have developed a novel alignment procedure to mitigate these challenges and enhance the signal-to-noise ratio between classical E-FISH and amplified E-FISH techniques that limit variation of the electric field induced by optomechanical components.

[1] Hogue et al.,  Opt. Lett. 48, 4601 (2023).

[2] Billeau et al., Appl Opt. (2024)