Laboratory for Microwave Photonics and Magnonics named after B. A. Kalinikos

Scientific results:

• Using the apparatus of Hamiltonian formalism, we have built a theory of nonlinear spin-wave excitation of by microstrip antennas. Relying the built theory and computations based on it, we have compared the influence of two types of nonlinearity on the amplitude of the excited spin wave. For the first time we have established the main physical mechanism responsible for the nonlinearity of the characteristics describing the excitation of spin waves by microstrip antennas. This mechanism is the four-wave parametric interaction of spin waves in the part of the magnetic film that is placed immediately beneath the antenna.

• We have developed a theory of the formation of nonlinear transmission characteristics of an active ring resonator accounting for the nonlinear dispersion and attenuation of surface spin waves.

• The Laboratory has conducted a research of the influence of such parameters of an active ring resonator as the coefficient of amplification of the open ring, the intensity of the external magnetic field and the input dimensionless amplitude of spin waves on the formation of nonlinear transmission characteristics.

• It has been demonstrated that increasing the amplification coefficient up to the self-generation threshold leads to the expansion of the frequency range of bistability, while if the amplitude of spin waves is sufficiently small, the influence of nonlinear attenuation can be neglected. It was shown that increasing the magnetic field intensity ensures an increase of the nonlinear coefficient, which also leads to an extension of the frequency range of bistability. It has been found that increasing the input amplitude of spin waves leads to an extension of the frequency range of bistability, however, the impact of nonlinear attenuation in this mode is much more pronounced. The obtained results were used in the research of the nonlinear dynamics of spin waves in magnonic ring resonator systems to improve their performance.

• We have developed a numerical model for the computation of the operational characteristics of reservoir computation system built upon a spin-wave active ring oscillator in which data input is performed by changing the coefficient of amplification of the feedback loop. The model relies on the Ginzburg–Landau equation describing the nonlinear phase shift and the nonlinear attenuation of the operating spin waves.

• On the basis of the developed numerical model, we have created a set of computer programs to determine the efficiency of reservoir systems. As the main assessment criterion we chose the capacities observed as a result of a short-term memory check and a parity check. These tests allowed to assess two main parameters of efficiently, namely, memory and nonlinearity of the reservoir.

• We have developed a physical implementation of a reservoir computer with a time delay based on a ring resonator with a spin-wave delay line. It has been demonstrated that this system, due to the dynamics of spin waves, is able to implement properties necessary for the reservoir, such as nonlinearity and attenuating memory. Introducing a reference line into the scheme of the reservoir computer allowed to improve the nonlinear computation capacity without a sharp decrease of the volume of attenuating memory. We have performed performance tests of the reservoir computer and it turned out that the performance of the developed reservoir computer is higher then the capacity of examples known from literature.

• Our researchers have developed a theoretical model of the operational characteristics of a reservoir computing system relying on nonlinear interferometers. In this case, one leg of the interferometer is a spin-wave delay line operating in the nonlinear mode. Another leg of the interferometer is a microwave attenuator and a phase shifter. We have researched the transmission characteristics of a ring resonator based on a nonlinear spin-wave interferometer. It has been demonstrated that changing the phase on the phase shifter by π in the second leg of the interferometer allows to completely suppress the bistable behavior. As a result of the conducted research, we found that the use of nonlinear integro-differential schemes allows to increase the parity check capacity while preserving the short-term memory capacity, which allows to improve the performance of reservoir computation systems.

Implemented results of research: 

We are conducting negotiations with enterprises of the industry to develop an industrial sample of the reservoir computer .

Education and career development: 

• We have developed education programs (including lecture courses, laboratory case studies, practical classes) in the area of our project: «Artificial neural networks based on principles of physical electronics», «Radiophotonics and fiber optics». These education programs have been implemented into the education process.

• The academic team of the Laboratory organizes and stages the annual international conference «Microwave electronics and microelectronics».

Collaborations: 

«Inzarus» Ltd, «Powplay Systems» Ltd (Russia): conducting R&D in the domain of the project