The paper deals with the design of an micro-optical part of a WDM transceiver based on the circle volume holographic grating triplexer (VHGT) topology. The work is focused on detail description of the bidirectional micro-optical insertion system, especially on the coupling in the transmission direction of the WDM transceiver optical part. This micro-optical wavelength distribution system is imagine transmission system consisted of collimating cylindrical lenses set in the circle topology with the VHGT filter placed in the middle of the circle. The topology is described by ray matrices equations, calculated using analytic and numeric methods and optically measured. Considering simulation and measurement results of micro-optical insertion system the influence of these characteristics on ray path attenuation, diffraction efficiency and transceiver performance is estimated. The paper also discusses limits and conditions of the laser asymmetrical beam focus into the input/output optical fiber.
We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.
Design, fabrication and RNF measurement of the optical multi-mode interference power splitter 1 to 2 with graded refractive index is reported. The design was developed by utilizing numerical solutions using the finite difference beam propagation method for operation wavelength 1550 nm. The deposition tests that led to the fabrication of the proposed structures were made after designing the structures. Several samples of optical MMI splitters 1x2 were obtained by Ag+↔Na+ two step field assisted ion exchange process in molten salt into a new special optical glass substrate for ion exchange technology. The refractive index profile of the channel waveguide was verified by the direct measurement near-filed method by the Refractive Near Field Profilometer.
KEYWORDS: Waveguides, Channel waveguides, Silver, Ion exchange, Refractive index, Ions, Near field, Near field optics, Channel projecting optics, Scanning electron microscopy
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.
This paper presents the design results, simulation and construction of WDM wavelength division multiplexer-bidirectional transceiver module (WDM-Transceiver) for the passive optical network (PON) of a fiber to the home FTTH topology. WDM transceiver uses a microoptics hybrid integration technology with volume holographic Bragg grating triplex filter (VHGT) and a collimation lenses for wavelength multiplexing/ demultiplexing.
We report about fabrication and properties of Gallium Nitride (GaN) layers doped with erbium or mixture of erbium and
ytterbium ions. Transmission spectra in the spectral range from 280 to 800 nm taken by the spectrometer Varian Cary
50 showed that the increasing concentration of the dopants shifts the absorption edge to the lower wavelengths. Optical
band gap Eg was determined from the absorption coefficient values using Tauc's procedure and the obtained values
varied from 3.08 eV to 3.89 eV depending on the erbium or erbium plus ytterbium doping. Photoluminescence emission
at 1 530 nm due to the Er3+ intra-4f
4I13/2 → 4I15/2 transition was observed by using excitation of semiconductor lasers
operating at 980 nm.
This article describes design of the photonic receiver composed of the system polymer planar waveguides, InGaAs p-i-n
photodiode and integrated HBT amplifier on a low loss composite substrate. The photonic receiver was the main part of
the hybrid integrated microwave optoelectronic transceiver TRx (transciever TRx) for the optical networks PON (passive
optical networks) with FTTH (fiber-to-the-home) topology. In this article are presented the research results of threedimensional
field between output facet of a optical waveguide and p-i-n photodiode. In terms of our research, there was
optimized the optical coupling among the facet waveguide and pi-n photodiode and the electrical coupling among p-i-n
photodiode and input of HBT amplifier. The hybrid planar lightwave circuit (PLC) of the transceiver TRx will be
composed from a two parts - polymer optical waveguide including VHGT filter section and a optoelectronic microwave
section.
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.
We report about properties of epoxy novolak resin polymer doped with dysprosium ions. The polymer layers were
fabricated by spin-coating onto silicon substrates, or pouring epoxy novolak resin solution into bottomless molds placed
on a quartz substrate and leaving them to dry. Rather strong bands around 3366 cm-1 in the infrared spectra indicated
presence of the O-H groups. Absorption measurements were done in the spectral range from 300 nm to 3000 nm and
showed six strong bands at 758 nm (6F3/2), 807 nm (6F5/2), 906 nm (6F7/2), 1100 nm (6F9/2), 1280 nm (6F11/2) and 1685 nm
(6H11/2) corresponding to Dy3+ ions. Optical band gap Eg was determined from the absorption coefficient values using
Tauc's procedure, i.e., from the relationship αhv = A(hv - Eg)2 and the obtained values varied from 3.489 eV to 3.539 eV
depending on the amount of dysprosium ions involved in the samples. Photoluminescence spectra around 1300 nm were
investigated by using excitation of He-Ne laser (632.8 nm) and two semiconductor lasers (980 nm and 827 nm).
We report about properties of Gallium Nitride layers doped by Erbium and Erbium/Ytterbium ions. The GaN layers were fabricated by Metal Organic Chemical Vapor Deposition on sapphire substrate, and Er3+ and Yb3+ ions were incorporated into the deposited layers by using ion implantation. After the implantation the samples were annealed in nitrogen atmosphere. The structures of the GaN samples were examined by the X-Ray Diffraction analysis; composition of the samples was measured by Rutherford Backscattering Spectroscopy and Elastic Recoil Detection Analysis. The GaN layers had single crystalline hexagonal wurtzite structure and content of Er3+ and Er3+\Yb3+ ranged from 0.05 to 3.38 at. %. The photoluminescence measurement was carried out at excitation of λex = 632.8 nm (temperature 4 K) and λex = 980 nm (room temperature). Photoluminescence spectra taken at 4 K showed typical erbium 4I13/2→4I15/2 emission bands. Some of our samples exhibited the desired emission even at the room temperature, which indicated that the samples were of a good quality what concerned their crystallographic homogeneity, as well as distribution and appropriate concentration of the Er3+ and Yb3+.
We report about fabrication and properties of Gallium Nitride (GaN) layers containing the Rare Earth (RE) ions. Gallium nitride is a promising wide band gaps direct semiconductor material, which doped with the RE ions would play a very important role in various optoelectronics and photonics applications. The GaN thin films were deposited by magnetron sputtering in Ar + N2 gas mixture using Ga2O3 target as the source of Gallium. For the RE doping, the Er2O3, Yb2O3, Pr2O3 and Nd2O3 pellets, or Er and Yb powder were laid on the top of the Ga2O3 target. The GaN layers were deposited on silicon, silica on silicon, Corning glass or quartz substrates. The results of the experiments were evaluated in terms of the relations between the technology/precursors approaches and the composition and luminescence properties of the fabricated thin films.
Erbium (Er3+) and Ytterbium (Yb3+) ions doped Gallium Nitride (GaN) layers were deposited by RF magnetron sputtering. Deposition was carried out in Ar + N2 gas mixture using Ga and Ga2O3 target as the source of Gallium. For the erbium and ytterbium doping, the Er2O3, Yb2O3 pellets, or Er and Yb powder were laid on the top of the Ga2O3 target. The GaN layers were deposited on silicon and Corning glass substrates. The properties of the GaN layers were investigated by using X-ray diffraction, Raman spectroscopy, absorption spectra and photoluminescence spectra. Prism coupling mode spectroscopy was used to measure the waveguiding properties. The composition of the fabricated samples was determined by using nuclear chemical analysis as Rutherford Backscattering Spectroscopy (RBS) and Elastic Recoil Detection Analysis (ERDA). The results of the experiments were evaluated in terms of the relations between the technology approaches and the composition and luminescence properties of the fabricated thin films. Up to now the best results, which can be utilized for a structure operating at 1550 nm (when pumped at 980 nm), were obtained when using (erbium plus ytterbium) metallic powder and Corning glass as the substrate for the deposition.
We report on fabrication of the GaN layers deposited onto silicon, silica-on-silicon and quartz glass substrates by RF magnetron sputtering. The GaN layers were also doped with erbium ions to achieve active optical properties. The fabricated layers were characterized by a number of methods and the results are discussed on the bases of quality of the deposited GaN structures.
Study of fabrication and properties of the carbon layers by using the PACVD (Plasma Assisted Chemical Vapor Deposition) apparatus is reported. The layers were grown on silicon substrates with methane as the precursor and were then doped with the erbium ions by treating the fabricated samples in glycerin or in the solution of erbium nitrate. To obtain deeper erbium containing carbon layers (up to 1 μm) the “sandwich method” was used based on repetition (three times) of carbon deposition and subsequent 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.
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 (CNx) 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 ionsso that the resulting structures can also be used as active waveguides.
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