l3: laboratory of micro/nano photonics - imt

IMTIMT-Bucharest Scientific R-Bucharest Scientific Report 2010eport 201016

European Centre of Excellence in Microwave, Millimetre Wave and Optical Devices, based on Micro-Electro-Mechanical Systems for Advanced Communication Systems and Sensors, MIMOMEMS

L3: Laboratory of micro/nano photonicsL3: Laboratory of micro/nano photonics

Mission: Research anddevelopment activities in thefield of micro/nano-photonics and optical MEMSfocused on the development

of micro/ nano structures based on new materials andprocesses and photonic integrated circuits based onheterogeneous integration technology; development ofmaterials, technologies and components for optical MEMS.

Main areas of expertise� modeling and simulation of micro and nano photonicstructures; development af simulation tools� new materials for micro/nano opto-electro-mechanicalsystems integration (e.g. compound semiconductors,functional polymer, hybrid organic-inorganic nano-compozites and glasses), and related fabricationprocesses (including mixed technologies); � passive and active micro-nano-photonic structures, � hybrid or monolithic integrated photonic circuitsand MOEMS (including heterogeneous platforms) foroptical communications, interconnects and optical signalprocessing;� micro-optics - design and fabrication based onreplication techniques� plasmonics� optical and electrical characterization of materials anddevices

European ProjectsFP7: �Flexible Patterning of Complex Micro Structuresusing Adaptive Embossing Technology, FlexPaet, IP, NMP;�European Centre of Excellence in Microwave, MillimetreWave and Optical Devices, MIMOMEMS, CSA-programme capacities;MNT-ERANET: �Multifunctional Zinc-Oxide basednanostructures: from materials to a new generation ofdevices (MULTINANOWIRES)

National Projects:� Development of soft lithography techniques for microand nano-photonics- National Program “Partnership”� Development of processes and devices based on oxidicand polymeric thin layers for transparent Electronics andOptoelectronics- National Program “Partnership”� Multifunctional molecular architectures for organicelectronics and nanotechnologytheoretical andexperimental studies- National Program “Ideas”

The Research team has multidisciplinary expertise and iscomposed of 6 senior researchers (5 with PhD inoptoelectronics, materials for optoelectronics,microsytems, physics, chemistry), 2 PhD students (withphysics and electronics background), 1MSc student.

Specific facilities:

Modeling and simulation: • Opti FDTD 9.0 - designand simulation of advanced passive and nonlinearphotonic devices• OptiBPM 10.0- design of complex optical waveguides,which perform guiding, coupling, switching, splitting,multiplexing and demultiplexing of optical signals inphotonic devices• OptiGrating- design software for modelling integratedand fiber optical devices that incorporate optical gratings• Opti-HS - components and of active devices based onsemiconductor heterostructures • LaserMod - analysis of optoelectronic devices byperforming electrical and optical analysis of III-V andother semiconductor materials. • 3Lith – 3D micro-optical elements• Zemax

Characterization: • spectrophotometers for UV-VIS-NIRand IR spectral range; • spectroscopic ellipsometer;• High Resolution Raman Spectrometers LabRAM HR • Alpha300 S System – combines the characterizationmethods of Scanning Near-field Optical Microscope(SNOM), Confocal Microscopy (CM) and Atomic ForceMicroscopy (AFM)• experimental set-up for optoelectric characterization inUV-VIS-IR spectral range of optoelectronic and photoniccomponents, circuits

Technology: glove box for preparation and deposition ofnanocomposites and organic layers

• Mission

• Main areas of expertise

• European Projects

• Research Team

• Specific facilities

Dr. Dana Cristea received a MSc in Electronics (1982) and PhD in Optoelectronics and Materials forElectronics from “Politehnica” University, Bucharest, Romania. Between 1982-1994 she was a researchscientist in the Department of Optoelectronics and Sensors at Research & Development Institute forElectronic Components, Bucharest, Romania.

Since 1994 she has been a senior researcher in the National Institute for R&D in Microtechnologies (IMT-Bucharest), Romania, head of Laboratory for Micro/Nanophotonics since 1997 and head of Departmentfor Multidisciplinary Research between 2002 and 2008; since 1990 she has also been an AssociateProfessor at “Politehnica” University, Bucharest, Faculty of Electronics.

Her main research activities are in the fields of optoelectronics and photonic integrated circuits, optical MEMS, newnanostructured materials for photonics, chemo and bio-sensors, micro-optics. She wrote for more than 80 publications ininternational scientific journals and conference proceedings, and is also a reviewer for Romanian and International scientificjournals. Dr. Dana Cristea has coordinated more than 20 national projects, has participated in several FP6 projects(WAPITI, 4M, ASSEMIC), and is currently involved in two FP7 projects (FlexPAET, MIMOMEMS).

Laboratory Head — Dr. Dana Cristea ([email protected])Laboratory Head — Dr. Dana Cristea ([email protected])

Cristian Kusko, Roxana Tomeascu, Munizer Purica, Mihai Kusko,Paula Obreja, Roxana Rebigan, Florin Comanescu,

Elena Budianu, Dana Cristea.

IMTIMT-Bucharest Scientific R-Bucharest Scientific Report 2010eport 2010 17

LaborLaboratory of Micro/Nano Photonicsatory of Micro/Nano Photonics

ResultsResults

MIMOMEMS

Nanocomposite materials with controlled optical properties for micro-optics

The nanocomposites have been obtained fromcommercial polymers (PMMA, PVA) and dopants:metal (Ag), metal oxide nanoparticles (TiO2, ZrO2) ororganic materials (Rhodamine, Alq3) by chemicalroutes and sol-gel processes. The optical propertiesof these materials depend on the composition,metal/oxide concentration, particle size anddispersion homogeneity. Micro/nano patteringtechniques based on combination of electron beamlithography and replication techniques have beendeveloped to obtain structures with applications inmicro-optics.

PN II Project (2007-2010), “Development of soft lithography techniques for micro and nano-photonics” – LISOFTPN II project (2009-2011) Program Ideas „Multifunctional molecular architectures for organic electronics and nanotechnology-theoretical and experimental studies”. Contract No. 617/2009; Contact person: Dr. Paula Obreja ([email protected])

Dispersion of the refractive index of PMMA-TiO2 film.

XTEM image of PMMA-TiO2film (dTiO2 = 5-10 nm). TiO2

nanoparticles are uniformdispersed in the film.

Real and imaginary refractive index of Ag – PVA film

XTEM images of Ag-PVA film (d Ag = 5 - 30 nm)

Surface plasmon enhanced emission from RhBdoped PMMA/Au strips at λ=600 nm (excitationwith λ=530 nm) - application in biosensing and

OLEDs

Dispersion of the refractive index of dye dopedPMMA films

Micro optical components in polymers

Replica molding technique was used to replicate micro-optical components (lens,array lenses), components for micro-fluidic applications and to generate nano-components in polymers with different feature size.

PN II Project (2007-2010), “Development of soft lithography techniques for micro and nano-photonics”Coordinator: IMT Bucharest, Project manager: Paula Obreja ([email protected])

Optical images of an array lensesreplicated in epoxy resin

Optical images of Fresnel lens replicated in epoxy resin SEM images of a lens and an array lenses replicated in PDMS


MIMOMEMS


3D Electron beam lithography in for μμ- and n-optics

3D-profile structures with feature size in the submicron range, for applications in photonics (photonic crystals, opticalwaveguides, and holograms) were obtained by EBL in multi-layer resist systems. If the polymers that compose themulti-layers have different charge sensitivity and/or different dissolution rate, the remaining structure after exposureand development will have a 3D profile. T-shape and suspended structures can be obtained in by-layer systemsPMMA950K /PMMA495K PMMA 950K/LOR and /PMMA950K/ PMMA35K. The exposure parameters and the developmentprocess were optimized and calibrated for each type of structures.

IMT core program Convert- project PN 09 29 02 05; Cooperation with Microphysical characterization laboratory (EBL, SEM).

Structures obtained by EBL in bi-layer system PMMA 950K/LOR: a) SEM image of suspended PMMA waveguides; b) SEMimages and c) AFM – 2D image of PMMA photonic crystal (suspended PMMA membrane for with holes of 200 nm diameter

and pitch of 500 nm)

a b

c

Techniques for regioregular poly 3-hexyl tiophene (rr-P3HT) deposition for OFETs

Thin layers of rr-P3HT were deposited by spin-coating or drop casting in N2 atmosphere, on SiO2 or SiO2 functionalizedwith trimethylchlorosilane. The best results (enhanced crystalinity and higher conductivity) were obtained for the layersdeposited by drop-casting on functionalised SiO2.

PN II project (2009-2011)-Program Ideas „Multifunctional molecular architectures for organic electronics and nanotechnologytheoretical and experimental studies”. Contract No. 617/2009

I-V characteristics of the rr-P3HT resistor (S-D) with width 2000 nm,length d1 =30 nm, d2 = 50 nm, d3 = 80 nm, 100 nm

XRD profile of the rr-P3HT thin films prepared bydrop-casting on functionalised SiO2

Schematic structure of the testdevice AFM images of rr-P3HT thin films prepared by drop-casting on functionalised

SiO2: a) topography; b) phase image

ResultsResults

Postdoctoral grants Sectorial Operational Programme Human Resources Development (SOP HRD) financed by the EuropeanSocial Fund and by Romanian Government: POSDRU/89/1.5/S/63700.

� p and n type - In1.64Sn0.16Zn0.2O3-5. (ZITO) transparent oxideslayers. - high transparency: > 88%;- polycrystalline structure with <222> preferential orientation;- thickness: 120-200 nm.


ResultsResults

MIMOMEMS

IMTIMT-Bucharest Scientific R-Bucharest Scientific Report 2010eport 2010 19

� p-NiO/n-ITO transparent heterojunction.

Glass substrate with p-NiO/n-ITO transparent

heterojunctions withcircular geometry of 0.6

mm2 area.

Reverse I-V characteristic ofp-NiO/n-ITO heterojunction

illuminated with UV radiation.

Electrical conductivity vs reverse temperature.

� p-NiO/Ti Schottky barrier.

The I-V characteristic of NiO/Ti obtained withelectrical AFM method (AFM tip covered with Ti)at very low currents (~10 nA) showed forwardbias of 2V and breakdown voltage>4V.

Heterojunctions with semiconductor transparent thin films of p-type

� Transparent polymericnanocomposites layers of PDMS-SiO2-TiO2 by sol-gel method.

Transparent films

PN II, Contract no: 12128/2008,“Development of processes and devices basedon oxidic and polymeric thin layers fortransparent Electronics and Optoelectronics -ELOTRANSP; Co-operation with ICMPP, Iasi.Co-ordinator: IMT-Bucharest; Project manager: Dr. Munizer Purica ([email protected])

Optical image of transparentpolymeric nanocomposites films.

Microphotonic sensors with biomedicalor environmental applications

This project aims to design and fabricatemicrophotonic sensors based on photonic integratedcircuits. The sensing principle is surface plasmonresonance (SPR) and the interaction betweenenvironment and the guided evanescent wave.

Contact person: Dr. Mihai Kusko, [email protected]

Theoretical and experimental investigation ofplasmonic systems

This project aims to investigate theoretically and experimentallythe optical radiation confinement in metallic waveguides withapplications in optical signal processing and sensors. Thepropagation of field in subwavelength metallic structures hasbeen investigated using the finite difference time domain andbeam propagation method. Geometrical parameters andfunctional characteristic havebeen identified.

Contact person: Dr. Cristian Kusko, [email protected]

The I-V characteristic of NiO/Ti by conductive –AFM method: a) direct bias; b) reverse bias

Theoretical shift of thephotonic crystal

transmission spectrumfunction of the refractiveindex of the environment(green n =1.33; red n=1.345; blue n =1.36)

Field distribution in a subwavelengthplasmonic nanoring resonator

Spectral characteristic of asubwavelength plasmonic

nanoring resonator (red line).


MIMOMEMS


ResultsResults European projects

Flexible Patterning of Complex Micro Structures using Adaptive Embossing Technology

Grant agreement no.: 214018 (IP, FP7, NMP-2007-3.5-2)Coordinator: Fraunhofer Institut für Produktionstechnolgie (Germany). Partners: Oy Modines Ltd. (Finland), ZumtobelLighting GmbH (Austria), CEA LITEN (France), Gaggione (France), Eitzenberger Luftlagertechnik GmbH (Germany),Johann Fischer Aschaffenburg Präzisionswerk GmbH & Co (Germany), Datapixel S.L.(Spain), Innovalia (Spain), TemiconGmbH (Germany), IPU (Denmark), IMT-Bucharest (Romania), Fundacion Privada Ascamm (Spain) Contact person for IMT: Dr Dana Cristea [email protected]

� Optimization of the embossing process for large area diffractive optical elements

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 scatteringelements located on its lower surface, a relation giving the distribution of scattering elements leading to a uniformirradiance along the LGP has been found. The validity of the theory has been verified by performing ray tracingsimulations. 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 knowledgeregarding the outcoupling coefficients of the scattering elements their embossed configuration and the intrinsic lossesof the LGP has been elaborated. This algorithm relies on online luminance measurements. The validity of this algorithmhas been verified by performing ray tracing simulations and a logical diagram describing the logical flow of themeasurement and embossing operations has been proposed.

Contact persons: Dr. Cristian Kusko ([email protected]), Dr. Mihai Kusko ([email protected])

� Thermal transient analysis of the embossing step

We performed design/simulations with CoventorWare software forthermal transfer of the embossing steps for two types of tools (Ni-Shimtool with 25 pixels and 4 pixels40x40um tool) and considered apolymeric substrate with highthermal conductivity or acommercial one with less highthermal conductivity. In order todecrease the temperature of thePMMA surface between theembossed pixels (thus the alreadyembossed pixels are notmelted/damaged) we considered forcooling an air flow on surfacesbetween substrate and tool.

Cooperation with Simulation, Modeling and Computer Aided Design Laboratory.Contact person: Rodica Voicu ([email protected])

The irradiance for a waveguide embossedwith a distribution of scatterers generatedfor a k=0.0017 obtained from simulation

(circles) and theory (solid line).

The ray tracing simulations illustratingthe step by step adaptive embossing

algorithm

The simulated irradiance for a structurerealized with multipixel stamps

Simulations results of temperatures at0.3 s with air cooling

The different temperatures (with air cooling andwithout air cooling) in the PMMA substrate

between two pixels for the tool with 4 pixels at0.3s, Step 1, Initial temperature of Ni at 150 oC,

air gap 30 um

l3: laboratory of micro/nano photonics - imt

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