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In the paper new areas of the fiber-optic Sagnac interferometer applications are discussed and proposed. Because this system detects the absolute rotation, its application is directly designed for detection of the seismic rotation waves which are rotational events existing in the seismic waves. In most cases those waves are extracted from recordings of differential seismic signals. However, all differences in responses of the seismometers cause disturbances which obscure these hidden components as it is for two antiparallel pendulum seismometers (TAPS) system. The presented device, named fiber-optic rotational seismometer (FORS), is free from this disadvantage and may be used for other rotational seismometer calibration, as well as for direct seismic rotation waves detection. The paper describes the design based on a well-known optical gyroscope configuration but with its optimization for its optimization for detection the absolute rotation, only. The obtained results have been the source of TAPS work improvement by applying the data smoothing by a spline function. Moreover, the first application of FORS for recording rotational parts existing in the seismic events has shown that they probably propagate with different velocity than classical earthquake waves. [ABSTRACT FROM AUTHOR]

We have performed nonlinear optical and piezoelectric studies of the Rb1-xKxTiOPO4 (RKTP) (with x = 0.01 and 0.002) single crystals irradiated by γ-quanta at power 1.23 Gy. We have found that for non-irradiated samples with x = 0.01 the effective second-order susceptibilities determined from the powder-like micrometer samples were less than for x = 0.02 and the effective values of the second-order susceptibilities for 1064 nm were equal to 3.12 pm/V (x = 0.002) and 2.56 pm/V (x = 0.01). After the gamma irradiation the corresponding values were equal to 2.45 pm/V and 2.78 pm/V, respectively. Moreover, for the samples with x = 0.01 one can observe the occurrence of the damage at laser energy density equal to about several J/cm2. Such effect is absent for the pure KTP crystals and may be a consequence of substantial role of the intrinsic defects caused by insertion of potassium ions in the positions of the rubidium cations. At the same time the piezoelectrical constants show an opposite behavior with respect to the SHG. [ABSTRACT FROM AUTHOR]