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3The 30th International Conference on Advanced Laser Technologies P-P-2
ALT'23
Investigation of mode propagation in waveguide structures with
chalcogenide glasses
A. E. Mitrofanova1'2'4, I.D. Skuratov12, V.V. Svetikov3'4
1- JSC «Molecular Electronics Research Institute», Moscow, Russia
2- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
3- Prokhorov General Physics Institute, RAS, Moscow, Russia
4- JSC «Zelenograd Nanotechnology Center», Moscow, Russia
mitrofanova. ae@phystech. edu
Currently, chalcogenide materials are widely used to create memory cells. Such devices are based on the principle of changing optical and electrical properties when the phase state of glass changes from amorphous to crystalline. The phase state is switched using heat from laser or electric pulses.
The research of Ge-Sb-Te (GST) glasses, which have a strong optical contrast [1] and a short phase state switching time (50 ms) [2], receives special attention. This opens up the option of using GST-225 (Ge2Sb2Te5) thin films in optical switching devices. GST-225 has a high refractive index in both crystalline (n=8.03) and amorphous (n=4.69) phase states [3,4].
The possibility of creating a discrete phase shift using components that is based on GST-225 thin films was investigated in the work. Waveguide structures based on SOI were calculated.
■10.4 -10.2 -10.0 -9.8 -9.6 -10.4 -10.2 -10.0 -9.8 -9.6
Horizontal Direction (|jm) Horizontal Direction (|jm)
Figure 2. Waveguide geometry and field distribution in a waveguide
In the wok presented computational analysis of the phase change of the waveguide mode and waveguide losses as variables of the phase state of the GST film and the geometric parameters of the structure: the thickness of the film (10-30 nm) and the thickness of the buffer layer (0-100 nm). Based on the results, an optimal model of a waveguide with a 75nm buffer layer and a 10nm GST film (Fig.1) is offered. A 5° phase shift on the length of a 1.94 micron GST segment is achieved, with losses of approximately 0.7 dB for a crystalline GST section and 0.1-0.2 dB for an amorphous GST section. Based on the results, a switch model based on the Mach-Zehnder interferometer has been constructed. The phase shift between signals passing in different arms must be 45 degrees. However, creating an optimal phase difference can be difficult because it requires a difference in the optical path between the two channels equal to A/8. To make the correction, discrete sections of GST film were placed on both arms of the interferometer. By changing the phase state of the GST, it is possible to change the phase rotation by 1-15°, achieving the exact final phase shift of 45 ° required for the switch's operation.
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