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modelling, simulation and CAD of micro and nano photonic structures |
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 Optoelectronic devices |
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| Optoelectronic GaInAsP/InP active and passive photonic devices based on microring resonator (vertical coupling) |
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analysis of the waveguiding properties and spectral characteristic of a microring resonator obtained by wafer-bonding technology
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design and 3D simulation of microring resonator, all-optical wavelength converters, multifunctional devices
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lay-out design
Project Waferbonding And Active Passive Integration Technology
And Implementation - WAPITI, STREP FP 6 /IST, 2004-2007.
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Vertically coupled micro-ring resonator -: a) example of structure; b) radiation coupling from bus to ring;
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example of transfer characteristics for a passive structure; d) lay-out |
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Integrated optics |
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Investigation of plasmonic systems with applications in optical signal processing and sensors |
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Postdoctoral grants POSDRU/89/1.5/S/63700
Contact person: Dr. Cristian Kusko |
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Field distribution in a subwavelength
plasmonic nanoring resonator
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Spectral characteristic of a subwavelength plasmonic nanoring resonator (red line).
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| Design of microphotonic sensors for biomedical and or environmental applications |
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Photonic integrated sensor on silicon substrate based on the configuration of Young interferometer is simulated with Beam Propagation Method. The core and cladding materials of the photonic sensor are polymeric materials. This sensor works for the detection of the surrounding medium refractive index variation. From the far-field fringe displacements it has been obtained that their position shift with 118 microns if the refractive index of the analysis medium varies from 1.33 to 1.36. The sensing window length is 400 microns, the reference and sensing waveguides are placed 20 microns from each other and the distance between Young interferometer and the sensing element is 10 mm. The interfringe distance is about 315 microns.
Postdoctoral grants POSDRU/89/1.5/S/63700
Contact person: Dr. Mihai Kusko |
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Simulated far field pattern
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Radiation propagation in polymeric Young interferometer.
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| Design of a thermooptical modulator based on SOI waveguides |
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There is an increasing interest in the area of relatively low-speed, low cost modulators and switches for local area networks (LANs). Silicon is an appropriate material for modulation based on thermo optic effect due to its high value of the thermo optic coefficient. The silicon waveguides can be used for devices working at wavelengths centered around 1.55 μm, since the silicon is transparent in this wavelength domain. Achievements: it was designed a Mach-Zehnder modulator based on silicon on insulator (SOI) waveguides. It was used optical analysis for designing a single mode, polarization insensitive Mach-Zehnder interferometer and for solving the coupling issues regarding transition from the rib waveguide to the rectangular section waveguide used in the active zone. Also, it was used the thermal analysis for determining the required applied voltage for switching from ON to OFF state. The obtained value is 2.6 V. The software packages employed were OptiBPM 8.0 software based on BPM (Beam Propagation Method) provided by Optiwave for the optical analysis and Coventorware 2006 software provided by Coventor Inc. for the thermal analysis The results obtained will be used for fabrication of a thermo optical modulator. |
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Propagation in a Mach-Zehnder interferometer
if there is a temperature difference between the arms:
a) ΔT = 0 K; b) ΔT = 4 K |
Transversal section
temperature distribution
in the structure. |
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Microoptics |
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Optimization of the embossing process for large area diffractive optical elements |
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Project: Flexible Patterning of Complex Micro Structures using Adaptive Embossing Technology (FlexPAET),
IP FP7 NMP-2007-3.5-2 2008-2011. Coordinator: Fraunhofer Institut für Produktionstechnolgie (Germany).
A theoretical framework for finding the optimal distribution of scattering elements in an edge-lit light guide plate (LGP) presenting intrinsic absorption losses for rendering a uniform distribution of the outcoupled light has been elaborated. Based on a simple mathematical model describing the light propagation in an LGP with a distribution of scattering elements located on its lower surface, a relation giving the distribution of scattering elements leading to a uniform irradiance along the LGP has been found. |
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The validity of the theory has been verified by performing ray tracing simulations.
The simulations show a quantitative agreement between the analytical results and the simulated ones, confirming the mathematical model [M.Kusko, C. Kusko, and D. Cristea, J. of Optical Soc. Of America 27].
A step by step adaptive algorithm for designing and optimizing a LGP with uniform radiance having no prior knowledge regarding the outcoupling coefficients of the scattering elements their embossed configuration and the intrinsic losses of the LGP has been elaborated. This algorithm relies on online luminance measurements. The validity of this algorithm has been verified by performing ray tracing simulations and a logical diagram describing the logical flow of the measurement and embossing operations has been proposed.
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The irradiance for a waveguide embossed
with a distribution of scatterers generated for
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k=0.0017 obtained from simulation
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ray tracing simulations illustrating
the step by step adaptive
embossing algorithm |
The simulated irradiance for a structure realized with multipixel stamps |
Contact persons: Dr. Cristian Kusko, Dr. Mihai Kusko |
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| Thermal transient analysis of the step-embossing process for large area DOEs |
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We performed design/simulations with CoventorWare software for thermal transfer of the embossing steps for two types of tools (Ni-Shim tool with 25 pixels and 4 pixels 40x40um tool) and considered a polymeric substrate with high
thermal conductivity or a commercial one with less high thermal conductivity. In order to decrease the temperature of the PMMA surface between the embossed pixels (thus the already embossed pixels are not melted/damaged) we considered for cooling an air flow on surfaces between substrate and tool.
Project: Flexible Patterning of Complex Micro Structures using Adaptive Embossing Technology (FlexPAET)
Cooperation with Simulation, Modelling and Computer Aided Design Laboratory
Contact person: Dr. Mihai Kusko |
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Simulations results of temperatures at
0.3 s with air cooling
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The different temperatures (with air cooling and
without air cooling) in the PMMA substrate
between two pixels for the tool with 4 pixels at
0.3s, Step 1, Initial temperature of Ni at 150 oC,
air gap 30 um
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| Design of the diffractive optical elements |
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Diffractive Optical Elements (DOEs) are used in many areas like optical communication, optical interconnection, sensors, beam shaping, etc. The team from our laboratory designs DOEs using analytical expressions in the case of the Fresnel lens or diffraction grating and the dedicated software 3Lith provided by Raith. Gmbh for DOEs with complex function. The designed DOEs are based on discrete levels configuration (2, 4 and 8 levels).
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Optical MEMS |
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| Design of reflective microoptics components on silicon substrates movable micromirrors |
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Movable micromirrors represents one of optical- MEMS devices which are widely used in different types of applications such as cross connects and switches in optical systems, laser adjustable cavities, miniature scanning devices, communication and sensors applications. Movable micromirrors can be actuated by different means, such as electromagnetic actuation, electrostatic actuation, piezoelectric actuation and thermal actuation based on bimorph layer or a resistance integrated on silicon substrates . After performing micromirrors simulations using Coventorware software, the micromirrors with different geometry were obtained on on silicon or SOI substrates by wet etching, RIE, thermal oxidation, lithography and metal deposition by vacumm evaporation technique.
MINASIST+ project No. PN06240303 (2006-2008). Contact person Dr. Munizer Purica
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Displacement versus applied voltage for micromirror with
different geometry on silicon substrate
(inside-stress distribution on structures) |
SEM image of micromirrors with circular and rectangular geometry obtained on silicon substrates |
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Last update:
January 19, 2012 |
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