Vaclav Prajzler

Design and investigation of properties of nanocrystalline diamond optical planar waveguides

Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.

Erbium doping into thin carbon optical layers

Abstract Study of fabrication and properties of the carbon layers by using the plasma assisted chemical vapour deposition apparatus is reported. The layers were grown on silicon substrates with methane as the precursor. The fabricated samples were then doped with Er 3+ by treating them in solution of erbium nitrate in glycerin. To obtain deeper erbium containing carbon layers the ‘sandwich method’ was used based on repetition (three times) of carbon deposition and subsequent Er 3+ diffusion of erbium after which followed annealing in vacuum oven. The obtained results proved that it is in principle possible to fabricate the erbium containing carbon thin optical layers.

Optical and Spectroscopic Properties of Polymer Layers Doped with Rare Earth Ions

This chapter deals with description properties of a number of Rare-Earth (RE) ions in polymer materials. The list of the RE elements with some of its basic properties are shown in Table 1. The electronic structure of each trivalent RE element consists of partially filled 4f subshell, and outer 5s2 and 5p6 subshell. With increasing nuclear charge electrons enter into the underlying 4f subshell rather than the external 5d subshell. Since the filled 5s2 and 5p6 subshells screen the 4f electrons, the RE elements have very similar chemical properties. The screening of the partially filled 4f subshells, by the outer closed 5s2 and 5p6 subshell, also gives rise to sharp emission spectra independent of the host materials. The intra-subshell transitions of 4f electrons lead to narrow absorption peaks in the ultra-violet, visible, and near-infrared regions.

Design and construction of a VHGT-attached WDM-type triplex transceiver module using polymer PLC hybrid integration technology

We report about design and construction of the bidirectional transceiver TRx module for subscriber part of the passive optical network PON for a fiber to the home FTTH topology. The TRx module consists of a epoxy novolak resin polymer planar lightwave circuit (PLC) hybrid integration technology with volume holographic grating triplex filter VHGT, surface-illuminated photodetectors and spot-size converted Fabry-Pérot laser diode in SMD package. The hybrid PLC has composed from a two parts-polymer optical waveguide including VHGT filter section and a optoelectronic microwave section. The both parts are placed on the composite substrate.

The Investigation of the Waveguiding Properties of Silk Fibroin from the Visible to Near-Infrared Spectrum

Silk fibroin protein has been reinvented as a new optical material for biophotonic applications because of its optical transparency, biocompatibility, and easy fabrication process. It is used in various silk-based optical devices, which makes it desirable to investigate the optical properties of silk from diverse perspectives. This paper presents our investigation of the optical properties of silk fibroin, extracted from Bombyx mori cocoons. We have measured transmission spectra from the visible to near-infrared region and investigated waveguiding properties by the prism-coupling technique for five wavelengths (473.0, 632.8, 964.0, 1311, and 1552 nm). From the measurements, we determined the values of refractive indices. The measurements also proved waveguiding properties for all of the wavelengths. Optical scattering losses were measured by the fiber probe technique at 632.8 nm and were estimated to be 0.22 dB·cm−1.

Burying of channel optical waveguides - relation between near-field measurement and Ag concentration profile

Two-step field-assisted ion-exchanged waveguides have been fabricated on a glass substrate. The concentration profiles of the exchanged ions were measured with electron microprobe. The waveguides were characterized under scanning electron microscope and optical microscope for the investigation of burying structures. Guiding mode patterns were characterized with near-field measurement, where symmetric profiles were observed for the burying-type waveguide. The refractive index profiles were also measured with a modified end-fire coupling method. The relation between ion concentration profiles and index profiles were compared for the waveguides with different fabrication process.

WDM hybrid microoptical transceiver with Bragg volume grating

The paper presents the design, simulation and construction results of the wavelength division multiplex bidirectional transceiver module (WDM transceiver) for the passive optical network (PON) of a fiber to the home (FTTH) topology network. WDM transceiver uses a microoptical hybrid integration technology with volume holographic Bragg grating triplex filter -VHGT and a collimation lenses imagine system for wavelength multiplexing/ demultiplexing. This transmission type VHGT filter has high diffraction angle, very low insertion loses and optical crosstalk, which guide to very good technical parameters of transceiver module. WDM transceiver has been constructed using system of a four micromodules in the new circle topology. The optical micromodule with VHGT filter and collimation and decollimation lenses, two optoelectronics microwave receiver micromodules for receiving download information (internet and digital TV signals) and optoelectronic transmitter micromodule for transmitting upload information. In the paper is presented the optical analysis of the optical imagine system by ray-transfer matrix. We compute and measure VHGT characteristics such as diffraction angle, diffraction efficiency and diffraction crosstalk of the optical system for 1310, 1490 and 1550 nm wavelength radiation. For the design of optoelectronic receiver micromodule was used the low signal electrical equivalent circuit for the dynamic performance signal analysis. In the paper is presented the planar form WDM transceiver with polymer optical waveguides and two stage interference demultiplexing optical filter as well.

Characterisation of hydrogen and erbium in carbon layers fabricated by PACVD for optical applications

Abstract Carbon films prepared by plasma assisted chemical vapor deposition were doped by laser active ion Er 3+ . The characterisation of the layers was performed using Rutherford backscattering spectrometry and elastic recoil detection analysis. Optical properties of the waveguides were measured at 660 nm wave length using standard prism spectroscopy. The correlation between the layer composition and the content of incorporated erbium and layer optical properties shows very interesting aspects [SPIE 4281, San Jose (2001) 13].

Thin carbon and carbon nitride films for passive and active optical waveguides

Thin carbon and carbon nitride films exhibit specific optical and mechanical properties which make them promising materials for integrated optics. For this purpose we have investigated the preparation and optical properties of carbon and carbon nitride (CN x ) films deposited on silicon substrates. The contribution deals with the study and fabrication of planar optical waveguides on semiconductor (silicon) substrates by the method of Plasma Assisted Chemical Vapor Deposition (PACVD). This waveguide is a carbon or carbon nitride layer deposited in a PACVD apparatus on a layer of silicon oxide, which also provides optical shielding of the substrate and is prepared by the oxidation of a silicon substrate wafer. The carbon as well as carbon nitride layers were fabricated by the reaction of methane, methane and nitrogen or methane and ammonia, respectively, in the PACVD apparatus. The fabricated films were characterized by optical ellipsometry and standard mode spectroscopy at 633 nm. The attenuation of the best sample was less than 0.3 dB/cm. It was found that optical and mechanical properties of films fabricated on the positive and negative electrodes were substantially different. The films deposited on the negative electrode were harder and their refractive index was higher compared with those deposited on the negative electrode. The refractive index of the harder films ranged from 2.2 to 2.6, while for the softer films it ranged from 1.6 to 1.8. We proved that it is in principle possible to dope the deposited layers with erbium ions so that the resulting structures can also be used as active waveguides.

Erbium Luminescence Centres in Single- and Nano-Crystalline Diamond—Effects of Ion Implantation Fluence and Thermal Annealing

We present a fundamental study of the erbium luminescence centres in single- and nano-crystalline (NCD) diamonds. Both diamond forms were doped with Er using ion implantation with the energy of 190 keV at fluences up to 5 × 1015 ions·cm−2, followed by annealing at controllable temperature in Ar atmosphere or vacuum to enhance the near infrared photoluminescence. The Rutherford Backscattering Spectrometry showed that Er concentration maximum determined for NCD films is slightly shifted to the depth with respect to the Stopping and Range of Ions in Matter simulation. The number of the displaced atoms per depth slightly increased with the fluence, but in fact the maximum reached the fully disordered target even in the lowest ion fluence used. The post-implantation annealing at 800 °C in vacuum had a further beneficial effect on erbium luminescence intensity at around 1.5 μm, especially for the Er-doped NCD films, which contain a higher amount of grain boundaries than single-crystalline diamond.