Femtosecond Photorefractive Optical Transient Detection in the Blue

Optical phase measurement is important for detecting minute changes in the property of light such as wavefront distortion, and refractive index variations. Traditional interferometers are often susceptible to environmental perturbations, resulting in degraded measurement accuracy. Optical transient detection (OTD) is an adaptive interferometric technique for optical phase detection with enhanced background suppression, while compensating for slow environmental fluctuations, commonly based on two-wave mixing (TWM) in photorefractive crystals [1]–[3]. Here we report on femtosecond OTD in Barium Titanate, BaTiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> (BTO) photorefractive crystal using TWM pumped in the blue, to detect weak and fast phase fluctuations by injecting a phase-triggering signal, to set the system in quadrature condition, and enable enhanced signal-phase detection with SNR up to 40 dB. To the best of our knowledge, this is the first demonstration of OTD using up-converted visible femtosecond pulses.