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We investigate the dynamics of Pearcey pulses in the highly noninstantaneous Kerr media. Setting appropriate pulse power and relaxation time of the media, an interesting phenomenon is found that the Pearcey pulse will exhibit an energy transfer property during propagation. We further investigate the evolution characteristics by changing the pulse power and relaxation time of the media, while keeping a constant ratio in the simulation. It is shown that the transversal motion of Pearcey pulses is proportional to the ratio between the pulse power and relaxation time of the media in the highly noninstantaneous limit.

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Different from the abruptly autofocusing induced by the linearity, we report a new type of abruptly autofocusing induced by the defocusing nonlinearity. By investigating the dynamics of the outward-focusing ring Pearcey-Gaussian (PeG) beam in defocusing nonlinear media, it is found that the propagation of the beam exhibits an abruptly autofocusing behavior of simultaneous intensity (the degree of the nonlocality) and position (the amplitude of the beam) control via adjusting the variable function. Our original findings represent the first theoretical realization of abruptly autofocusing behavior induced by the defocusing nonlinearity and can potentially be applied in optical tweezers and the optical switch.

In this Letter, we propose a single-beam nonlinear magneto-optical rotation (NMOR) magnetometer with a multipass 4He gas-discharged cell. In contrast to the single-pass cell, the multipass cell allowed laser beams to pass through the metastable-state atomic ensemble 22 times, which directly increases the optical path length and significantly enhances magneto-optical rotation in the 4He gas sample. Based on nonlinear Faraday rotation, the 4He magnetometer with the multipass cell demonstrates a noise floor of 9 fT/Hz1/2, which approaches the photon-shot noise floor limit of 6.4 fT/Hz1/2. In addition, the wider linewidth in metastable-state atoms realizes an NMOR 4He magnetometer with a 3 dB bandwidth of 4.3 kHz, in contrast to the ultranarrow linewidth in the antirelaxation-coated cells or spin-exchange relaxation-free regime alkali-metal cells with buffer gas. Since the 4He cell functions without heating or cryogenic cooling, the femtotesla sensitivity and kilohertz-bandwidth 4He magnetometer exhibits potential in biomagnetic applications such as magnetocardiography and magnetoencephalography.