Jedrzej Nowosielski

Nanostructured elliptical gradient-index microlenses

We show theoretical and experimental characterizations of a nanostructured gradient-index lens. The elliptical lens is a nonguiding element fabricated using the mosaic method, which is widely used for the fabrication of photonic crystal fibers. For the first time we show experimental data in the optics regime that confirm the effective medium approximation for discrete mosaic structures with subwavelength feature size. This opens the door for the development of general asymmetric gradient-index materials.

Form birefringence in nanostructured micro-optical devices

We present a detailed examination of the design and expected operation of an artificially birefringent material based around the nanostructured stack-and-draw fabrication technique developed recently. The expected degree of birefringence is estimated using a Finite Difference Time Domain simulation of the physical system and is shown to be in agreement with that predicted by a second order effective medium theory treatment of the nanostructured material. The effects of finite device dimensions are studied and an estimate of the required device thickness for a half-wave retardation is made.

Large diameter nanostructured gradient index lens.

In this paper we report on the development and optical properties of nanostructured gradient index microlenses with good chromatic behavior. We introduce a new fabrication concept for the development of large diameter nanostructured gradient index microlenses based on quantized gradient index profiles and the use of nanostructured meta-rods. We show a dependence of the quality of performance on the number of refractive index levels and the lens diameter. Measurements carried out at 633 and 850 nm show good optical properties and similar focal lengths for both wavelengths.

Silicate all-solid photonic crystal fibers with a glass high index contrast

An all-solid photonic crystal fiber can be developed using two thermally matched glasses with one glass forming the background, and the other the lattice of inclusions. Optical properties of all-solid holey fibers (SOHO) are sensitive to the photonic cladding configuration, much the same as PCFs with air holes, and strongly depend on dispersion properties of the materials used. When a high index contrast between the glasses is assured photonic crystal fiber can effectively guide light with photonic band gap mechanism. This can be easily achieved when multicomponent soft glass is used for fiber fabrication. We report on new developments of F2/NC-21 silicate all-glass PCFs. F2 is a commercially available glass (Schott Inc.) with a high concentration of lead-oxide (PbO=45.5%) and the refractive index nD=1.619. It can be used both as the background material and as a material for micro-rods (inclusions). A borosilicate glass (B2O3=26.0%) NC-21 glass has been synthesized in-house at IEMT. NC21 has the index nD=1.533 and was used as the material for micro-rods (inclusions) or as a background glass in the structures. The two selected glasses have a high index contrast equal to 0,084 at 1,55μm wavelength. In this report we present new results on optimization of the filling factor d/Λ and reduction of the lattice pitch Λ necessary to obtain efficient guidance at 1.55 μm. The numerical analysis of SOHO F2/NC21 fibers has been carried out using a full-vector mode solver based on the plane-wave expansion method. In our paper we report on photonic crystal fibers with two guiding mechanisms: an effective index with a high index core (low index inclusions made of NC21 glass and F2 used as a background glass) and a photonic band gap with a low index core (high index inclusions made of F2 glass and NC21 used as a background glass).

Diffractive optics development using a modified stack-and-draw technique.

We present a novel method for the development of diffractive optical elements (DOEs). Unlike standard surface relief DOEs, the phase shift is introduced through a refractive index variation achieved by using different types of glass. For the fabrication of DOEs we use a modified stack-and-draw technique, originally developed for the fabrication of photonic crystal fibers, resulting in a completely flat element that is easy to integrate with other optical components. A proof-of-concept demonstration of the method is presented-a two-dimensional binary optical phase grating in the form of a square chessboard with a pixel size of 5 μm. Two types of glass are used: low refractive index silicate glass NC21 and high refractive index lead-silicate glass F2. The measured diffraction characteristics of the fabricated component are presented and it is shown numerically and experimentally that such a DOE can be used as a fiber interconnector that couples light from a small-core fiber into the several cores of a multicore fiber.

Nanostructured micro-optics based on a modified stack-and-draw fabrication technique

Abstract We present the latest results in the fabrication of micro-optical components using a novel nanostructuring process. This low-cost fabrication technology, which exploits advances in the development of photonic crystal fibres, uses a modified stack-and-draw technique where macroscopic distributions of thermally and mechanically matched glasses are reduced in scale by repeated draw-down and restacking procedures until the individual glass features are significantly below the wavelength of incident light. We demonstrate that this fabrication technique is suitable for the creation of large diameter high numerical aperture micro-lenses for light collection and concentration purposes and broadband form birefringent materials.

Fabrication of solid-cladding photonic band gap fiber with air core

In this paper we report on fabrication of all-Solid photonic Cladding and Air Core fiber (SCAC fiber). As far as we know it is a first reported fabrication of such PCF. Microrods are made of commercially available lead-oxide F2 glass (SCHOTT Inc.) with a refractive index nD=1.619, while as background we use a borosilicate NC21 glass synthesized in-house at ITME with a refractive index nD=1.533. A fabricated fiber has a lattice constant of Λ≈7.49μm and microrods diameter of d≈4.0μm. Air core has a diameter of DR=3.67μm and total fiber diameter is Dfiber=123.80μm.

Experimental implementation of zero order quarter and half wave plates using customised nanostructured birefringent material

This paper will present the latest results concerning the development of such a set of wave plates and demonstrate that they can be used to manipulate the polarisation state of a wide range of incident wavelengths in a fibre optic system. An analysis of the issues and limitations surrounding the fabrication procedures associated with the customised birefringent material will also be presented - particularly those issues that need to be overcome to allow the design and fabrication of components that are not limited to use in fibre optical systems.

Development of elliptical nanostructured gradient index microlens

In this paper, we demonstrate the feasibility of using the nanostructured micro-optics technology to create a large diameter quantized elliptical microlens. Nanostructured gradient index elements have discrete internal structure with feature sizes much smaller than the wavelength of the incident light. The nanostructured lens is composed of two silicate glasses with various refractive indexes. Large diameter elliptical microlens is developed. Optical performance of microlens is verified numerically. Effective focal lengths of 220 and 116 for are predicted for wavelength of 1300 nm.

Customised birefringence in nanostructured micro-optical devices

We present the design and fabrication details of a customised nanostuctured form birefringent material based upon a second order effective medium theory composite composed of two mechanically and thermally matched soft glasses. The design, which shows uniform birefringence over several hundred nanometres, is fabricated using a modified stack-and-draw method to produce a final element with feature sizes in the 50-100nm range. A method for measuring the effective birefringence of the composite material is presented along with the preliminary results from the fabricated component.