Fabrication and integration of nanostructured optical devices

Abstract

The main goal of this thesis is the numerical and experimental verification of the concept of nanostructured micro-optical elements integrated into an optical fibre. The elements are fabricated with a stack and draw technique. This technology, based on the wellknown method of photonic crystal fibres (PCFs) production, allows the fabrication of Nanostructured Gradient Index (nGRIN) microlenses and axicons with individual nanorods with diameter of 100-300nm. The necessary parameters of materials used in stack and draw method are described and two glasses are chosen for the nanostructured elements fabrication. The procedure of synthesis of clear and doped Poly(methyl methacrylate) (PMMA) is introduced, which will allow using PMMA in the future in stack and draw technique. Numerical simulations of a Gaussian beam focusing nGRIN microlenses attached to optical fibres are performed using a FFT BPM method. This shows that nGRIN microlenses can be described using the effective refractive index also in the case of the optical fibre illumination. The procedure of fabricating, cutting and polishing of elements 125 um in diameter and 20-60 um long is introduced and explained. Both simulation and experimental results show that the fabricated nanostructured lenses and axicons focus light for the fibre source with wavelength 1550nm.