Volume 45, Nº 12 (2018)

Magnetic fields are one of the main tools for controlling the interaction of ultracold atoms using the so-called Feshbach resonances. However, the accurate knowledge of magnetic fields within the high-vacuum chamber is significantly complicated due to the inexact knowledge of the setup geometry, the presence of magnetic parts, and other. In this paper, we demonstrate precision calibration of magnetic fields in the high-vacuum setup using microwave spectroscopy of the ground state of ultracold thulium atoms.

The evolution of radiation-induced absorption (RIA) of light at λ = 1.55 μmis compared after pulsed action of ionizing radiation at different probe light power in an undoped-silica-core Panda-type birefringent optical fiber and in an isotropic optical fiber drawn from the same preform before embedding the stress-applying rods.High efficiency of RIA photobleaching by the probe light at λ = 1.55 μm is revealed in the birefringent fiber.

The paper presents the results of experimental observations of stimulated low-frequency Raman scattering (SLFRS) on acoustic eigenvibration of graphitized layers of different thicknesses in single-crystal diamond volume excited by a nanosecond laser pulse.

For the first time, the effect of target surface plasma on nanosecond laser ablation is studied. Surface plasma was generated by a high-power cw fiber laser beam incident on an iron target. A comparison of laser ablation by nanosecond Nd:YAG laser pulses (1064 nm, 5 ns) was performed upon exposure to the cw laser and during its short-term (5 ms) turn off. It was found that the emission intensity twofold increases in the presence of surface plasma. The temperature and electron density of the laser plume induced by the nanosecond laser also increased.