Single-Frequency, Thin-Film-Tuned, 0.6W, Diode-Pumped Nd:YVO\u3csub\u3e4\u3c/sub\u3e Laser

Application of a metallic thin-film selector to the single-frequency oscillation of a diode-pumped Nd:YVO4 laser has been investigated theoretically and experimentally. We show that a chromium thin-film selector with a thickness between 8 and 9 nm provides single-frequency output within a power range of 0.6W. Single-frequency operation, slow smooth turning, or chirping was realized by the output coupler movement with a piezoceramic transducer. Chuirping at a repetition rate of 0.5 kHz in the 0.5-10-GHz range was achieved. Physical and technical limitations caused by the wide-gain bandwidith, thermal effects, and mechanical vibrations of cavity elements are discussed

Optimizing mixing in the Rudner-Levitov lattice

Here we discuss optimization of mixing in finite linear and circular Rudner-Levitov lattices, i.e., Su-Schrieffer-Heeger lattices with a dissipative sublattice. We show that presence of exceptional points in the systems spectra can lead to drastically different scaling of the mixing time with the number of lattice nodes, varying from quadratic to the logarithmic one. When operating in the region between the maximal and minimal exceptional points, it is always possible to restore the logarithmic scaling by choosing the initial state of the chain. Moreover, for the same localized initial state and values of parameters, a longer lattice might mix much faster than the shorter one. Also we demonstrate that an asymmetric circular Rudner-Levitov lattice can preserve logarithmic scaling of the mixing time for an arbitrary large number of lattice nodes.Comment: To appear in JOSA B, 202

Solid-state laser with self-stabilized or linearly chirped output frequency

The specific regimes of the linear tuning and the frequency self-stabilization were proposed and analyzed theoretically in a diode pumped solid-state laser with a thin-film metallic selector

The origin of paramagnetic magnetization in field-cooled YBa2Cu3O7 films

Temperature dependences of the magnetic moment have been measured in YBa_2Cu_3O_{7-\delta} thin films over a wide magnetic field range (5 <= H <= 10^4 Oe). In these films a paramagnetic signal known as the paramagnetic Meissner effect has been observed. The experimental data in the films, which have strong pinning and high critical current densities (J_c ~ 2 \times 10^6 A/cm^2 at 77 K), are quantitatively shown to be highly consistent with the theoretical model proposed by Koshelev and Larkin [Phys. Rev. B 52, 13559 (1995)]. This finding indicates that the origin of the paramagnetic effect is ultimately associated with nucleation and inhomogeneous spatial redistribution of magnetic vortices in a sample which is cooled down in a magnetic field. It is also shown that the distribution of vortices is extremely sensitive to the interplay of film properties and the real experimental conditions of the measurements.Comment: RevTex, 8 figure

Breaking reciprocity by designed loss

In this paper, we show how designed loss in open quantum systems can break the reciprocity of field propagation, and how non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear. In particular, we show how unidirectional propagation can be achieved for input states of certain symmetry in linear schemes, and demonstrate the possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build a non-reciprocal asymmetric field distributor with a planar structure of dissipatively coupled waveguides. We discuss the feasibility of the considered schemes and suggest possible realizations

Breaking reciprocity by designed loss

In this paper we show how designed loss in open quantum systems can break reciprocity of the state propagation, and how the non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear ones. In particular, we show how a unidirectional propagation can be achieved for states of certain symmetry in linear schemes, demonstrate possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build non-reciprocal circulator with a planar structure of dissipatively coupled waveguides. We discuss feasibility of the considered schemes and suggest possible realizations

Single-Frequency, Thin-Film-Tuned, 0.6W, Diode-Pumped Nd:YVO\u3csub\u3e4\u3c/sub\u3e Laser

Application of a metallic thin-film selector to the single-frequency oscillation of a diode-pumped Nd:YVO4 laser has been investigated theoretically and experimentally. We show that a chromium thin-film selector with a thickness between 8 and 9 nm provides single-frequency output within a power range of 0.6W. Single-frequency operation, slow smooth turning, or chirping was realized by the output coupler movement with a piezoceramic transducer. Chuirping at a repetition rate of 0.5 kHz in the 0.5-10-GHz range was achieved. Physical and technical limitations caused by the wide-gain bandwidith, thermal effects, and mechanical vibrations of cavity elements are discussed

СТАН ПОПУЛЯЦІЙ ТА ОХОРОНА ВЕСНЯНИХ ЕФЕМЕРОЇДІВ ФЛОРИ КОРНИНСЬКОГО ЗАКАЗНИКА

Досліджено особливості поширення, стану та структури популяцій весняних ефемероїдів Корнинського заказника для подальшого збереження цих рослин у регіоні