Volumetric thermochemical laser writing of nanostructured reflective diffraction gratings on a dual-layer material Zr/SiO2

Куц Р.И., Корольков В.П., Микерин С.Л., Окотруб К.А., Белоусов Д.А., Малышев А.И., Саметов А.Р., Шиманский Р.В., Гаврилова Т.А. Объёмная термохимическая лазерная запись наноструктурированных отражающих дифракционных решёток на двухслойном материале Zr/SiO2 // Оптический журнал. 2023. Т. 90. № 4. С. 5–17. http://doi.org/10.17586/1023-5086-2023-90-04-05-17

Kuts R.I., Korolkov V.P., Mikerin S.L., Okotrub K.A., Belousov D.A., Malyshev A.I., Sametov A.R., Shimansky R.V., Gavrilova T.A. Volumetric thermochemical laser writing of nanostructured reflective diffraction gratings on a dual-layer material Zr/SiO2 [In Russian] // Opticheskii Zhurnal. 2023. V. 90. № 4. P. 5–17. http://doi.org/10.17586/1023-5086-2023-90-04-05-17

Subject of study. Volumetric  thermochemical laser writing of nanostructured reflective diffraction gratings in a dual­layer Zr/SiO₂ material was studied. Objective. To study in detail direct laser writing on thin zirconium films on fused silica substrates in order to determine the reason of the anomalously large phase shift, as well as to investigate the possibility of creating reflective diffractive structures on its basis with a potential application in the component base of photonics. Method. Thermochemical writing with a focused laser beam on zirconium films deposited on fused silica substrates makes it possible to form oxide micropatterns. Depth measurements of their relief on an atomic force microscope show a surface relief no more than 10 nm deep, while measurement on a white light interferometer shows a relief up to hundreds of nanometers deep. Scanning electron microscopy and analysis of Raman spectra provide information on the internal structure and chemical composition of the modified regions. Main results. It is shown that the effect of laser writing of nanostructured reflective diffraction gratings on a dual­layer material is of a three­dimensional nature, since the layer is modified in depth by 50–60% more than the initial thickness of the Zr film. It has been demonstrated that phased gratings with a period equal to the laser beam scanning step are formed on the surface and in the depth of the modified layer. The modified layer, depending on the power of the writing beam, consists of a composition of oxide and zirconium nitride in amorphous or crystalline phases, including silicon oxide in the lower layer. The inner grating consists of channels in the modified layer, the cross section of which is near 80 nm. A hypothesis about the morphology and mechanism of formation of phased nanogratings has been proposed. Practical significance. It is proposed to supplement the “dry” one­stage technology for manufacturing binary reflective diffractive structures on a dual­layer Zr/SiO₂ material with a stage of reactive ion etching for diffraction efficiency adjustment.

Acknowledgment: the work was supported by a Grant from the Russian Science Foundation (Project No. 22­79­00049). The research used the equipment of the  Center for Collective Use "Spectroscopy and Optics" of the Institute of Automation and Electrometry of the Siberian Branch of the Russian Academy of Sciences, the Center for Collective Use "High Technologies and Nanosystems Analytics" of Novosibirsk State University and the Department of Scanning Electron Microscopy of the Center for Collective Use "Nanostructures" of the Institute of Semiconductor Physics of the Russian Academy of Sciences Siberian Branch.