This paper presents recent scheme based of direct dual wavelength laser writing of lightwave circuits developed in our laboratories. The system allows the fabrication of features of the order of ~1 micron by using a short wavelength laser to ablate a region preheated by a second laser.
A reflectance measurement technique was used to determine the refractive index distribution of optical waveguides
fabricated by a CW CO2 direct writing technique. The uniformity of refractive index has been verified along the
waveguides structure and used as input for accurate beam propagation method (BPM) calculations of waveguide
This invited talk presents the most recent work undertaken in our laboratory in the fields of direct laser writing of planar
optical integrated circuits, laser written micro fluidics circuits, laser machining of v-grooves and laser machining in
This paper presents recent research undertaken in our laboratory in the field of direct laser writing of microfluidics circuits. Our novel technology allows the rapid fabrication of complex fluidic circuits. The fabricated channel have smooth walls and surfaces enabling the encapsulation of the circuits.
In the present work, we describe innovative approaches and properties that can be added to the already popular thin film optically variable devices (OVD) used on banknotes. We show two practical examples of OVDs, namely (i) a pair of metameric filters offering a hidden image effect as a function of the angle of observation as well as a specific spectral property permitting automatic note readability, and (ii) multi-material filters offering a side-dependent color shift. We first describe the design approach of these new devices followed by their sensitivity to deposition errors especially in the case of the metameric filters where slight thickness variations have a significant effect on the obtained colors. The performance of prototype filters prepared by dual ion beam sputtering (DIBS) is shown.
We have studied theoretically the performance of symmetric and nonsymmetric Mach-Zehnder interferometer sensors with ridge and buried index profiles. The effect of device parameters on sensor performance is investigated, in particular of the window opening in symmetric and of the path length difference in nonsymmetric interferometers. Sensors with low losses are designed.
Low pressure plasma can effectively be used for the fabrication of films for optical waveguides and for the patterning of photonic devices. The present paper describes the basic physical and chemical processes during the plasma deposition of passive waveguides, particularly of silicon compound layers such as silicon oxide, nitride and oxynitrides. We give an overview of the effects of discharge parameters (reactor design, gas composition, energy of bombarding ions, substrate temperature) on the optical properties of the waveguide materials, and their relation to the microstructural and mechanical characteristics. Advances in plasma- fabricated photonic devices on silicon substrates are discussed.
Amorphous fluorocarbon polymers are attractive materials for optical applications because of their high transparency at wavelengths up to 3 micrometers because of the absence of C-H bonds. since 1989 DuPont's amorphous fluoropolymer Teflon AF is available, films of which can be fabricated by means of spin, spray, or dip coating from solution or by use of compression or injection molding from the melt. An alternative and promissing route for processing fluorocarbon films is the use of a low- pressure plasma: This technique can be employed for plasma polymerization of suitable fluorocarbon monomers and for controlled etching of fluorocarbon materials. In the present work, we present the characteristics of plasma-polymerized tetrafluoroethylene layers with a refractive index of approximately 1.4. Reactive ion etching in an N2O plasma is used for patterning these layers, and also the spin-coated Teflon AF films with a refractive index of around 1.3. Possibilities of fabricating passive and active polymer waveguide devices from flurocarbon polymers are discussed, and estimates of the expected waveguide performance are presented.
Optical properties of silicon-based coatings are investigated in which the refractive index n is varied gradually (SiOxNy with continuously changing x and y) or in discrete steps (SiO2/SiN1.3 multilayers). The films are prepared at room temperature in a dual- mode microwave/radiofrequency (MW/RF) plasma in which the substrates are placed on an RF powered substrate holder, while simultaneously exposed to a MW discharge. The films' composition is controlled by the working gas mixture using SiH4, NH3 and N2O, and their microstructure, such as packing density and interface roughness, is controlled independently by varying the energy and the flux of bombarding ions. The deposition process is monitored in-situ by optical emission spectroscopy measurements which are related to the compositional depth profiles provided by elastic recoil detection analysis.
SC923: From Understanding the Growth Of Optical Films to a Judicious Control of their Performance
This course provides the most recent background and understanding of two important aspects necessary for further advances in optical coatings:
A) Effect of energetic ion- and photon-induced reactions at the surface during the film growth by different complementary techniques including ion (beam) assisted deposition (IAD or IBAD), balanced and unbalanced magnetron sputtering (BMS and UMS), dual ion beam sputtering (DIBS), filtered cathodic arc deposition (FCAD), and plasma-enhanced chemical vapor deposition (PECVD), while concentrating on the most recent pulsed-discharge processes and time- and spatially-resolved diagnostic methods. This includes the principles and capabilities of the microstructural characterization methods suitable for materials assessment, for process optimization and for reverse engineering.
B) Metrology of the mechanical, tribological and other functional properties of optical films and their long term stability in various temperature, radiative and environmental conditions. It makes a link between the optical, mechanical and other characteristics, the film microstructure and the film growth mechanisms, allowing one to better perform film system optimization. This is illustrated by numerous practical examples of filter performance with discrete and graded designs ranging from antireflective coatings to complex telecom and astronomical filters to the optical coatings on plastics.