Anna Jusza

Luminescent properties of praseodymium doped Y2O3 and LaAlO3 nanocrystallites and polymer composites

Abstract Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr3+ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions concentration was prepared using sol-gel method and carefully characterized with respect to emission properties in the visible spectral range. In particular, the excitation and emission spectra were measured together with fluorescence decay profiles and the differences between optical properties of these materials were discussed and compared with data available for bulk materials. Finally, the PMMA-based composite materials doped with Pr3+:Y2O3 and Pr3+:LaAlO3 nanopowders were manufactured and characterized. The obtained results showed that polymer composites doped with active nanopowders in general tended to keep the luminescent properties of the original nanopowders.

Luminescent properties of polymer nanocomposites activated with praseodymium-doped nanocrystals

In this work we report the recent results of our investigation on visible emission properties of the polymer nanocomposites doped with oxide and fluoride nanopowders activated with praseodymium ions. The set of LaAlO3 and YF3 nanopowders differing in active ions concentration, was carefully characterized with respect of their structural and luminescent properties. Also the PMMA-based nanocomposites doped with these nanopowders were manufactured and characterized. The measurements of excitation and emission spectra as well as fluorescence decays enabled comparison of emission properties of nano-composites and original nanopowders and discussion of the main excitation and deexcitation mechanisms, responsible for the optical properties of developed materials. This, in turn will enable optimization of developed manufacturing technology.

Influence of Al2O3/Pr Nanoparticles on Soil, Air and Water Microorganisms

One of the greatest challenges for science nowadays is the protection of the natural environment. Synthetic nanoparticles are released into the environment with industrial and household wastes, and their release can be expected to increase constantly with increasing use of nanoparticles in industry and their increasing share in various consumer products. The penetration of nanoparticles into the water, soil, or air ecosystems may disturb seriously the functioning of the natural environment. In the present study we examined how the active aluminum nano-oxide in the gamma form used as a neutral carrier for the praseodymium (Pr) nanoparticles affected their behavior. Praseodymium is very useful in many branches of science and in everyday life, although in its free form, it is commonly considered to be cyto-toxic, eco-toxic, and phyto-toxic. Our experiments were aimed to find whether the aluminum nano-oxide can act as a nano-stabilizer for the metal nanoparticles, and also to examine whether their bounding on the carrier decreases or eliminates their toxicity to the soil or water microorganisms present in the natural environment. Our experiments have shown that the aluminum nano-oxide is suitable to function as a nano-stabilizer for the Pr nanoparticles. The Al2O3/Pr nanoparticles produced by the dry (conducted in an organic solvent) thermal decomposition of an organic precursor, are not ecotoxic, or less ecotoxic to bacteria isolated from environmental samples, in particular to gram-positive caryopsis of the Micrococcus and Staphylococcus genera isolated from air samples.

Synthesis and characterization of polymer composite base on RE3+:Al2O3 nanopowders doped by rare earth metals for application in optoelectronics

In this work we report the recent results of our investigations on synthesis the PMMA composite base on Al2O3 doped by ytterbium metal. The set of the Al2O3:Yb3+ composite samples was manufactured and examined with respect of their structural, physical and mechanical properties. The investigations have confirmed applicability of developed synthesis method to manufacturing of good structural quality, decent level of agglomeration, good homogeneity and good thermal stability consisting of nanoparticles with average size in the range of several tens of nanometers.

Synthesis and characterization of RE3+:Al2O3 nanopowders for application in the polymer-based composite light sources

In this work we report the recent results of our investigations on synthesis of RE3+:Al2O3 nanopowders prepared by a method, in which organic compounds are used as a solvent and lanthanide organic derivatives, and discuss structural and luminescent properties of the powders and PMMA-based composites doped with these powders. The set of the Al2O3 nanopowder samples doped with RE3+ ions (where RE = Yb and Er) was manufactured and examined with respect of their structural and optical properties. The first PMMA-based composites doped with In this work we report the recent results of our investigations on synthesis of RE3+:Al2O3 nanopowders prepared by a method, in which organic compounds are used as a solvent and lanthanide organic derivatives, and discuss structural and luminescent properties of the powders and PMMA-based composites doped with these powders. The set of the Al2O3 nanopowder samples doped with RE3+ ions (where RE = Yb and Er) was manufactured and examined with respect of their structural and optical properties. The first PMMA-based composites doped with Al2O3:RE3+ nanopowders have been manufactured and characterized in the context of their mechanical, structural and luminescent properties. The investigations have confirmed applicability of developed synthesis method to manufacturing of optically active nanopowders of reasonably good structural quality and homogeneity, consisting of nanoparticles with average size in the range of several tens of nanometers as well as possibility of developing the active composite material, based on PMMA polymer host.

Integrated interrogator circuits for fiber optic sensor network in generic InP photonic integrated circuit technology

Together with the development of fiber optic sensor networks the accurate and reliable operation of dedicated readout instruments became a critical issue. After years of optimizing the interrogating devices the use of photonic integrated circuits (PICs) has opened a new era of highly reliable, compact and versatile devices offering additionally advantages of low power consumption and cost-optimized design. Considering the most commonly deployed fiber Bragg grating (FBG) based sensor systems/networks, typically two PICs-based solutions for interrogators may be used: an arrayed waveguide grating (AWG) spectrometer with a broadband SLED source or a set of tunable laser sources with a photodiode detector. Among commercially available PIC technologies the InP platform has a substantial advantage as it allows fabrication of both passive devices (waveguide circuitry) as well as active devices (photodiodes and light sources) in the same technological process. In this work we investigate two different layouts of AWG-based integrated interrogators fabricated in generic technology of indium phosphide. We analyze the influence of crosstalk between AWG channels on operation of the device and possibility of interrogating narrow-band FBG reflection peaks as well as the influence of input polarization state on the AWG response, which is of fundamental importance for proper operation of an integrated FBG interrogator. As there is no polarization control elements available at present in the offer of generic InP technology providers we discuss the possibility of using off-chip solutions exploiting additional fiber-optic components. As a possible alternative to AWGbased interrogators, we discuss also the possibility of using integrated tunable lasers for FBG interrogation.

Noninvasive optoelectronic system for monitoring of the heart and respiratory rate of the patient exposed to MRI scanning (Conference Presentation)

The magnetic resonance imaging (MRI) technique is a powerful diagnostic tool which is nowadays commonly used in many fields of medicine. In some cases, especially of the patients of intensive care units, it is highly recommended or even necessary to provide continuous monitoring of basic physiologic parameters, mainly the heart rate and the respiratory rate, during the MRI scan procedure. The presence of a strong magnetic field within the MRI chamber requires application of non-standard devices and solutions. The monitoring system needs to be immune to the strong magnetic field and simultaneously cannot negatively influence on the results of the scan. Therefore, application of optical sensing technologies could be potentially advantageous to fulfil these requirements. In this work we propose a novel optoelectronic measurement system, dedicated to monitoring of the patient during an MRI scan, immune to strong magnetic field and compatible with the MRI apparatus. Fiber Bragg gratings (FBGs) are used as the sensing elements – the strain induced by the patient’s respiration and cardiac activity cause a change of the Bragg wavelength. These changes can be accurately measured and monitored in the time domain. The respiratory and heart rate can be extracted by further processing of the measured signal by dedicated software. The gratings are organized in a network to maximize the effective sensing area. Each of the FBGs has a different Bragg wavelength so that they can be connected in series. The information from the sensors is read out using an interrogator based on an application specific photonic integrated circuit (ASPIC), designed and fabricated in an InP-based generic integration technology. The interrogator comprises a 36-channel arrayed waveguide grating wavelength demultiplexer, which outputs are connected to PIN photodiodes. Such a photonic circuit acts as a spectrometer and allows to reconstruct the reflection spectrum of many gratings simultaneously. An external superluminescent LED is used as the light source, however in the target configuration the source could be monolithically integrated with the interrogator. The Bragg gratings, the interrogator and the SLED are connected with each other using an optical circulator. Initial tests of the monitoring system have been performed using a single fiber Bragg grating as the strain sensor and a commercially available optoelectronic interrogator. The fiber with an inscribed FBG was mounted using an epoxy glue on a PMMA board and deployed under the patient. Two signals can be distinguished out of the measured waves. The first one, with strong and slowly-varying peaks, reflects the respiration of the patient. The second signal, characterized by low-intensity and fast-varying peaks is a result of the cardiac activity. No influence of the magnetic field of the MRI instrument on the sensing system has been observed. The first results have confirmed both the correctness of the approach and the applicability of the system to monitoring the patient’s physical condition during MRI diagnosis. This work was supported by the National Centre for Research and Development, project OPTO-SPARE, grant agreement PBS3/B9/41/2015.

UV-VIS upconversion emission properties of Tm3++Yb3+:ZBLAN glasses (Conference Presentation)

Continuous demand for compact and efficient laser sources, specifically those operating in short-wavelength spectral range, have resulted in dynamic development of both semiconductor and diode pumped solid state lasers. Undoubtedly, semiconductor lasers are presently the most intensively investigated field of active materials and a number of impressive results has been achieved, including violet GaN laser diodes. Nevertheless, solid state lasers are constantly considered as irreplaceable in all applications requiring excellent optical parameters of the beam together with high power levels. The short-wavelength emission and lasing in solid state lasers is typically obtained via harmonic generation or up-conversion phenomena. The latter method, involving either stepwise absorption of photons or energy transfer processes, is specifically applicable to fiber geometry, where high intensity of radiation and waveguiding effect guarantee high up-conversion efficiency. Trivalent thulium is the activator ion, which energy structure in certain conditions specifically favours a multi-photon or multi-ion pumping mechanisms resulting in emission within the UV-VIS part of spectrum. In low phonon glasses and fibers, luminescence from 1G4 (480 nm), 1D2 (455 nm), as well as 1I6 (287 nm) has been reported, typically involving ESA-type consecutive absorptions of 650 nm photons (3H6→3F2+3F3, 3F4→1G4, 3H4→1D2, 1G4→3PJ) [1]. UV-VIS emission has been also observed under multi-wavelength pumping at 1112 nm, 1116 nm and 1127 nm [2]. Several years ago laser action at 287 nm in Tm3+:ZBLAN fiber was obtained under consecutive ESA of 1064 nm delivered by an Nd3+:YAG laser [3] – which is to date the shortest wavelength of stimulated emission generated in an optical fiber. Laser experiments with thulium-activated fluoride fibers, however very promising, were all severely hindered by photodarkening effects accompanying excitation of UV-violet radiation in the fibers. In this work we present our latest results on UV emission properties of bulk ZBLAN glasses doped with thulium and co-doped with ytterbium ions in different concentrations. In particular, we carefully examined the absorption characteristics, as well as concentration-dependant spectra of UV emission from the 1I6 and 1D2 levels obtained under direct and up-conversion excitation. The fluorescence dynamics profiles, recorded for all concentrations, together with excitation spectra enabled discussion of mechanisms responsible for upper levels populating. Moreover, the multi-ion processes resulting in non-radiative depopulation of excited states have been carefully examined and appropriate cross-relaxation rates have been determined, giving further impact to better understanding of the short wavelength optical properties of the investigated system. This work has been supported by the National Science Centre, Poland, grant number 2011/03/B/ST7/01917. [1] J. Y. Allain, M. Monerie, H. Poignant. Blue upconversion fluorozirconate fibre laser, Electronics Letters 26 (1990), 166–168. [2] S. G. Grubb, K. W. Bennett, R. S. Cannon, W. F. Humer, CW room-temperature blue upconversion fibre laser, Electronics Letters 28 (1992), 1243–1244 [3] R. M. El-Agmy, Upconversion CW Laser at 284 nm in a Nd:YAG-Pumped Double-Cladding Thulium-Doped ZBLAN Fiber Laser, Laser Physics 18 (2008) 1-4.

Polymer-based composite active fiber doped with Tm 3+ and Yb 3+ — Technology and luminescent properties in VIS spectral range

Recent years observed significant development of the technology of luminescent materials for application in light sources (both coherent and incoherent) operating in the visible part of the spectrum. Undoubtedly, the most spectacular results have been obtained in the field of wide bandgap semiconductor lasers, considerable progress has been also observed in solid state lasers based on crystalline or glassy hosts with frequency conversion. Despite this results, however, there is still a room for development of entirely new types of active media, like e.g. composite polymers doped with optically active nanocrystals. Such a materials may potentially benefit from excellent luminescent properties of RE3+ doped nanocrystals and good optical and thermo-mechanical properties of polymer matrices enabling drawing the optical fibers based on these composites. In such a design nanocrystalline environment provides the protection of active ions from interactions with highly energetic phonons of polymer matrix and simultaneously, polymer host encapsulating nanoparticles shields these from interactions with OH− groups and other contaminations.

An interferometrie fiber-optic gyroscope system based on an application specific photonic integrated circuit

Optical sensing techniques are considered as one of the most advancing and extensively investigated fields of photonics technologies. The fundamental advantages of optical sensors such as immunity to electro-magnetic interference, compact size and energy efficiency designate them to use in highly requiring applications, e.g. in harsh environment and aviation. Modern optical gyroscope systems, which are a critical part of inertial measurement units (IMU) of contemporary airplanes, drones, spacecrafts and others, are definitely one of the most impressive examples of successful implementation of photonic sensors [1]. Typically, the angular velocity is measured by utilizing the Sagnac effect occurring in rotating optical medium, which can be either an optical fiber loop or a ring laser [2]. Nowadays, commercially available gyroscopes are realized using discrete optoelectronic components, while in this work we present and discuss an interferometric fiber-optic gyroscope (IFOG) system, which uses a monolithic application specific photonic integrated circuit (ASPIC) as the readout device. The chip has been realized using the generic foundry approach [3]. We expect that application of such a compact photonic circuit will lead to reduction of the sensor weight and energy consumption with simultaneous increase of reliability of the device.