UDC 538.975:535.3:004.2:004.31
OPTIMIZATION OF THIN FILM STRUCTURE Ge2Sb2Te5 FOR OPTICAL SWITCHES
N. V. Vishnyakov, Ph.D. (Tech.), associate professor, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.
N. M. Tolkach, junior researcher, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.
P. S. Provotorov, master student, RSREU, Ryazan; This email address is being protected from spambots. You need JavaScript enabled to view it.
The problem of finding optimal parameters (layer thickness, wavelengths of information and control signal) of Ge2Sb2Te5 (GST) thin-film structure is studied. An optimal switching criterion was introduced to determine necessary parameters. In accordance with this criterion: in amorphous state of GST film, reflectivity should be maximum, transmissivity should be minimum; in crystalline state of GST film, reflectivity should be minimum, transmissivity should be maximum. The Fresnel-Airy model for multilayer media was used to calculate reflectivity and transmissivity of GST structure. Numerical methods of gradient descent, minimization and nonlinear optimization of functions were used to search for optimal parameters of GST structure. The aim is to optimize operating modes (reflection, transmission) of optical switch based on thinfilm structure of GST
Key words: thin-film structure, Ge2Sb2Te5 (GST225, GST), optical switch, phase state, amorphous state, crystal state, information signal, control signal, phase switching effect, reflectivity, transmissivity, optimal switching criterion.