This work proposes a method for lowering the energy of an optical impulse required to switch superconducting key
elements, based on driving such a components with the use of current and optical radiation impulses with varied lengths.
The investigation was conducted with the aid of numerical modelling of the superconducting switching element response
for a structure composed of a thin YBa2Cu3O7-x superconducting film deposited on a sapphire substrate (Al2O3) with a
buffer layer composed of strontium titanate (SrTiO3). It was proven that thanks to the driving with control impulses of
varied lengths, it is possible to switch such elements with 1.6 - 3.5 times lower energy of the optical impulse and the
current slightly higher than the critical current, as compared with the switching mechanism employing impulses with the
This paper features modelling the response of superconductor switching elements, carried out for the structures
composed from a film of YBa2Cu3O7-x deposited onto substrates SrTiO3 or Al2O3, controlled by current and laser pulses
with the length of 5&mgr;s. Based on these responses, threshold characteristics of switching and optimal (respectively to the
operation speed) control characteristics were obtained.
The method of an effective control of superconductor optoelectronic devices by commonly used current and optical radiation pulses is proposed. Numerical modeling of the resistive responses has been conducted for thin film structures based on high-Tc superconductor (HTS) YBa2Cu3O7-x. As a results of calculations, the control characteristics of HTS-switches in the form of switching time dependences on the control mode were obtained. On the basis of this, threshold characteristics of switching and optimal control characteristics of investigated elements were obtained. It is shown that applying of together acting current and laser radiation allows to effective switching of HTS-elements with significantly decreased pulses' amplitudes. Reduction of current amplitude lets to avoid thermal instability and reduction of needed radiation flux allows to apply semiconductor lasers.
Literature referring to superconductor optoelectronic switches report about curious phenomenon of improvement of dynamical properties as a result of introduction of a thin, low thermal conductivity buffer layer. Present paper is a trial of interpretation of this phenomenon basing on analysis of non-stationary temperature fields within the element's structure. The analysis has been made using the method of numeric modeling of thermal processes occurring within the thin-layer structure consisting of high-temperature superconductor YBa2Cu3O7-x sputtered over the LaAlO3 substrate and separated with an intermediate SrTiO3 layer. Numerical modeling is very difficult due to strong nonlinearity of resistivity in relation to temperature and current. The essential reason of shortening of key's switch-off time is the fact that the buffer layer limits heat diffusion towards the substrate during switching-on time; as a result its switching-off occurs through heat abstraction towards the high thermal conductivity substrate which temperature is lower than the superconductor's switch-off temperature.