Description
In Quantum Electrodynamics, vacuum becomes a nonlinear optical medium: its optical index should be modified in the presence of intense external electromagnetic fields. The DeLLight project (Deflection of Light by Light) aims to observe this effect using intense focused femtosecond laser pulses delivered by LASERIX. The principle is to measure with a Sagnac interferometer the deflection of a low-intensity focused pulse (probe) crossing the vacuum index gradient induced by a high-intensity pulse (pump). Given the current laser specifications and goal experimental parameters, the expected shift in the probe beam's barycenter is approximately 15 pm. To detect such a small signal with high confidence, achieving ultimate spatial resolution sensitivity is crucial. In this context, we propose a novel method to suppress high-frequency noise, thereby enabling access to this fundamental sensitivity limit.
