Physico-Chemical nanomaterials science

Resonant properties of volume grating-wavegiudes made in nanocomposite by holographic lithography method 
Hryn V.1, Yezhov P.1, Sakhno O.2, Bendziak A.3, Fito V.3, Smirnova T.1
1 Coherent and Quantum Optics Department, Institute of Physics of the NAS of Ukraine. Prospect Nauki, 46, Kyiv-03028, Ukraine.
E-mail: vohryn@iop.kiev.ua
2 Sensors and Actuators Department, Fraunhofer Institute for Applied Polymer Research. Geiselbergstraße, 69, Potsdam-Golm, 14476, Germany.
3 Department of Photonics, Lviv Polytechnic National University. Bandera street, 12, Lviv, 79013, Ukraine.

The grating-waveguide resonant properties, which appears like intensive and narrow peaks in reflection spectra from these structures, were studied.  Wavelengths of peak’s maxima depend on grating and waveguide parameters and refractive index of deposited on structure analyte.
The nanocomposite and method of recording layer with the thickness 1-2 µm fabrication were developed by our team. Volume gratings with period 400 nm was recorded in nanocomposite layer by holographic lithography method. This provides high recording speed (1-2 min) together with high uniformity of gratings for size up to 2 cm.
Theoretical analysis of the waveguide structures has shown that the spectral width of the reflection band (∆λ) is equal to 10-3-10-4 nm and reflection coefficient R is of about 0.99. Experimental measurement of the grating-waveguide spectral characteristics gives ∆λ = 0.012 nm and R = 0.13. Q-factor of this structure exceeds 50000.
Theoretical evaluations of the structure sensitivity to the environment refractive index changing were carried out. It was established, that sensitivity of the structure exceeds 100 nm/RIU for the angle of beam incidence 150; and minimal defined refractive index change is equal to 1.2x10-4.
Described grating-waveguides can be used for label-free sensing of chemical and biological agents.
This work was supported by the grant of the Science for Peace and Security (SPS) Program NATO, the Project SPS G5351.