Optical seminar. Ksenia Abrashitova


Lomonosova 9, room 1220

Ksenia Abrashitova

‘Two-photon laser lithography of planar and 3D optics for visible light and X-rays’

Abstract: The problem of manipulation of electromagnetic radiation at possibly the smallest scales is a challenging task for a full electromagnetic spectrum. It involves both advanced theoretical descriptions and cutting-edge micro- and nanofabrication techniques. Two-photon lithography is an advanced fully 3D micro- and nanofabrication technique. In the current lecture, we want to present our recent results in fabrication and studying of optical elements for visible light and X-rays made by two-photon lithography.

X-ray compound refractive lens (CRL) is a compact and easy-to-install focusing device analogous to а visible range glass lens. It is a stack of concave rotationally parabolic lenses put in a row. We for the first time demonstrated that two-photon lithography may be applied to make short-focus polymer X-ray CRL and characterized its optical performance at laboratory and synchrotron sources.

Bloch surface electromagnetic wave (BSW) in photonics crystals is a superior platform for compact integrated optical chips implementation compared to surface plasmons in metals. BSW is excited on the surface of dielectric 1D photonic crystals, the design of which defines BSW dispersion law. Structuring of photonic crystal top layer creates the spatial distribution of BSW effective refractive index and consequently allows us to control BSW propagation. А flexible and simple technique is needed to optimize the design of BSW integrated optical elements. We demonstrated that two-photon lithography with its high resolution and full geometrical freedom is a perfect instrument for prototyping of BSW optical elements with arbitrary levels of complexity.

The development of passive integrated optical elements technology is not sufficient for practical applications of integrated optical chip. All-optical switching active devices change their optical properties in response to incident electromagnetic field on femtosecond timescales. In case of optical Kerr effect, the medium changes its refractive index as an intense laser beam propagates through it. The optical Kerr effect may be a base for all-optical switching and characterized by the value of the Kerr coefficient. Quantum dots possess large values of the Kerr coefficient. Nanocomposite material — homogeneous mixture of quantum dots in polymer matrix — is a perfect material for all-optical switching active devices fabrication. The development of such a material is a challenging task, because of the tendency of quantum dots to agglomerate at high concentrations. We developed and studied nanocomposite materials based on CdSe quantum dots and SU-8 photoresist that may be structured by two-photon lithography.