The excitation and emission obtained from an Er3 + -doped tellurite glass with embedded silver nanoparticles (SNPs) through nanostructured surfaces consisting of a square lattice of nanoholes (squares or circles) in a silver thin film are addressed. The periodic nanostructures were fabricated with a focused gallium ion beam on a silver thin film deposited onto an Er3 + -doped tellurite glass with embedded SNPs. The Er3 + microluminescence spectra were measured in the far field (510- to 590-nm wavelength range). The emission observed through the plasmonic nanoholes is caused by the excitation of the Er3 + ions via extraordinary optical transmission from the periodic nanostructures. Two coupling types are proposed: (i) one between the SNPs and the Er3 + ions (electric dipole type) and (ii) a resonant coupling between the SNPs (localized surface plasmon resonance) and a silver thin film (surface plasmon polariton). These two couplings modify the local field, which improves the emission intensity of Er3 + . A dependence of the intensity emission with the geometrical shape of the nanoholes and the number of elements of the square lattice was observed. These findings can be very useful for nanophotonic device applications employing a transparent medium with optical gain.
Gold nanoparticle embedded in Er3+-Tm3+-codoped tellurite-glass are able produce two effects on the emission properties these glasses: (i) quenching on direct-emission under excitation by a 405 nm laser diode, or (ii) enhancement on upconversion-emission under excitation by a 976 nm laser diode in these glasses. Both effects were investigated from the luminescence decay dynamics of ions. The localized surface plasmon resonance band of gold nanoparticles at around 580 nm resulted in the quenching/enhancement of Er3+-Tm3+ emission for the Er3+:(4S3/2→4I15/2) transition. These hybrid materials can be utilized for various photonic applications, e.g. infrared to visible light converters or emitting green light.
Although the properties of extraordinary optical transmission (EOT) due surface plasmon polariton (SPP), which are
coupled in metallic slits have been widely studied in the last two decades, their influence on the absorption and
transmission spectra from their dielectric substrates has not been deserved the same attention. The choice of a good
substrate for implementation not just for gratings, but also for other devices, it is extremely important in order to achieve
great applications of the EOT. Good candidates to replace the conventional semiconductor based substrates are the rare
earth ions (REI) doped glasses. The specific case of Erbium ions and its implementation into glasses for the fabrication
of fiber optics, as Erbium doped fiber amplifiers (EDFA). The transmission observed through the plasmonic
nanostructures is elucidated considering the following effects: (i) white light absorption by the Er3+ ions, (ii) coupling
between the light and the nanostructure via the creation of surface plasmon polariton where the wavelengths with
minimums transmission corresponds to the 4I15/2 → [2H9/2, 4F3/2, 4F5/2, 4F7/2, 2H11/2, 4S3/2, 4F9/2] absorption levels the Er3+,
which propagates through the slits, and, finally, (iii) the Er3+ transmission intensity and the spectral shape -symmetry
depend on the nature of metallic film and the number of slits constituting the arrays, for which the resonant properties are
strongly affected. Furthermore, in order to compare the influence of substrate in the transmission properties, we also
performed the same measurements on slit arrays fabricated on the BK 7 glass.
New Yb3+, Er3+ and Tm3+ triply doped fluoro-phosphate glasses belonging to the system NaPO3-YF3-BaF2-CaF2 have been prepared by the classical melt-casting technique. Glasses containing up to 10 wt.% of rare-earth ions fluorides have been obtained and characterized by using differential scanning calorimetry (DSC), UV-visible-near-infrared spectroscopy and up-conversion emission spectroscopy under excitation with a 975 nm laser diode. Transparent and optically homogeneous glass-ceramics have been reproducibly obtained by appropriate heat treatment in view to manage the red, green and blue emissions upon 975 nm laser excitation. According to the applied thermal heat-treatment, a large enhancement of intensity of the up-conversion emission – from 10 to 160 times higher – has been achieved in the glassceramics compared to that of glasses, suggesting incorporation of the rare-earth ions into the crystalline phase. Furthermore, a large range of color rendering has been observed in these materials by controlling the laser excitation power and material crystallization rate. Time-resolved luminescence experiments as well as X-ray diffractometry and scanning electron microscopy techniques have been employed in order to understand and correlate the multicolor emission changes to the crystallization behavior of this material. A progressive phase transformation of the fluorite-type CaF2-based nanocrystals initially generated was observed along with increasing heat-treatment time, thus modifying the rare earth ions spectroscopic features.
Metallic negative-nanobowtie is a new suitable structure for development of nanoantennas that can be integrated on wide number of optical devices. Nevertheless, metallic negative-nanobowtie with absence of gap deserve attention special, because in addition to present similar properties from regular nanobowtie, can also interacts with different systems, like gain materials. One of remarkable class of such material is rare earth ions, not only for the enhancement on measured intensity, but also its easiness to implement it on glasses, which constitute the main type of substrate adopted on plasmonic structures. In this work we performed the analysis of effects due implementation of erbium (Er3+) rare earth ions into tellurite glass over a pattern of negative-nanobowtie on absence of gap between its tips, fabricated by focused ion beam (FIB) technique from gold (Au) films with 240 nm thickness. Here, the negative-nanobowties are vertically excited by an argon laser (Ar) at 488 nm and were performed to verify the dependence of nanobowtie’s geometry over the electric field along its symmetry axis. An asymptotic energy gap between the localized surface plasmon polariton modes and the ion spectral position was observed, which couple strongly with the 2H11/2→4I15/2 radiative emission of the Er3+. Besides, the 4S3/2→4I13/2 electronic transition is an indirect transition that was improve due to negative-nanobowtie in comparison with the 4I9/2→4I15/2.
Metallic nanobowtie is well known as a suitable structure for development of antennas that can be integrated on wide
number of devices, especially in optical communications. Such feature is achieved due the presence of surface plasmon
polariton (SPP) that provides a great charge density on nearby region from its tips. Considerable studies have described
theoretical and experimentally the influence of gap between tips on radiation emission, once this parameter may improve
the local field, as such length decrease. In optical regime, the emission enhancement is due the quantum-plasmonic
interaction created from tips’ region (localized field) and the transition levels from rare earth ion of erbium (Er3+) and
thulium (Tm3+). However, metallic nanobowtie with absence of gap still deserve attention, because in addition to present
similar properties from regular case as previously mentioned, can also interacts with different systems, like gain
materials, that can be embedded thermically into the substrate. Rare earth ion is one of the remarkable and suitable for
our proposition, not only for the enhancement on measured intensity, but also its easiness to implement it on glasses,
which constitute the main type of substrate adopted on plasmonic structures. In this work we performed the analysis of effects due implementation of Er3+ and Tm3+ ions into BK7 glass over a pattern of nanobowtie on absence of gap
between its tips, fabricated by focused ion beam (FIB) technique from gold (Au) films. The bowties were vertically
excited by an Argon laser (Ar) which wavelength ( ) is 488 nm. Furthermore, computational simulations based on finite
element method (FEM), were performed to verify the dependence of nanobowtie’s geometry over the electric field along its symmetry axis.
High crystalline quality erbium-doped zirconium oxide films were deposited on Si(100) by electron beam evaporation in high vacuum. Characteristics of light emission in the telecommunication window from erbium oxide crystal zirconium oxide films were investigated before and after furnace annealing in oxygen atmosphere. The luminescence intensity of the erbium-doped thin film after annealing at 900 °C was 18 times higher than those before thermal annealing. Also, it was observed a decrease in the intensity of luminescence and the 4I13/2 lifetime with the increase of the erbium concentration, which was analyzed via energy transfer - quenching. The structure environment of the erbium ion in the thin film before and after annealing has been studied by X-ray diffraction. The surface morphology of the films as a function of the annealing temperature and atmosphere showed a significant change.
Metallic nanostructures upon resonant excitation can enhance the local electric field, which could be increased, if these nanostructures are embedded in a gain medium. In this sense, we propose a gain medium as a candidate for the development of nanowaveguide amplifier based on Er3+-doped tellurite glass with embedded silver nanoparticles (NPs). Those glasses are characteristic for their amplifying response in the telecommunication window, and when we embedded metallic NPs modified the crystalline potential surrounding to the Er3+ ions, due to an electric coupling between NP (received/emitter) and Er3+ ion (emitter) enhancement luminescence intensity from the 4I13/2→4I15/2 transition radiative of the Er3+ ions. Besides, the presence these NPs changes the refraction index these glass modifying the complex parameter β(neff) increasing the polarizability of the samples f(Ɛd). Therefore, a gain medium – Er3+ ions (amplification function in the telecommunication band) with silver NPs (luminescence enhancement) – can increment the propagation length of light into nanowaveguide.
Periodic nanostructure arrays consisting of square holes were fabricated with a Focused Gallium Ion Beam on a gold thin film deposited onto the surface of an
Er3+-doped tellurite glass. The nominal dimensions of the square elements are approximately 300×300 nm2, separated by 1.0 μm, such that we have arrays of approximately 15×15, 10×10 and 5×5 μm2 dimensions. The metallic nanostructures were vertically illuminated with a diode laser at 405 nm. The Er3+ luminescence spectrum in the near-infrared was measured in the far-field via the micro-luminescence technique. The excitation and emission of the Er3+ ions were obtained through of the so-called extraordinary optical transmission of excitation and emission light, respectively, via those squares array. In this way, metallic nanostructures sustaining surface plasmons can excite and change the emission properties of the Er3+ ions. Additional contributions on the emission spectra were achieved due to the influence of the gold metal film, i.e., the resonant properties from the plasmonic nanostructures can strongly influence the spectroscopic features of the Er3+ ions. Therefore, we present a systematic quantum mechanical experiment that shows the quantum plasmonic properties of these nanostructure arrays on the erbium ions, with direct applications for understanding and exploiting of nanophotonic devices.
Currently, the focused ion beam milling (FIB) technique is a commonly used approach to fabricate nanostructures because of its unique advantages of one-step fabrication, nanoscale resolution, and no material selectivity, etc. However, the FIB technique also has its own disadvantages. Regarding the process of fabrication of the corrugations and subwavelength apertures, nowadays, there is a major problem: the V-shaped structuring. In this work, we discuss the influence of V-shape on the optical transmission of subwavelength slits designed in silver (Ag) and gold (Au) thin films possessing different thicknesses. The effect of different cone angles (ratio between the widths at the incidence plane and at the exit plane) originated from the V-shaped slits was also considered. We had performed computational simulations carried out with COMSOL Multiphysics® to investigate the slits optical transmission. In most cases, the subwavelength slits were illuminated with 488 nm (for Ag) and 632.8 nm (for Au) wavelength light sources in TM polarization (magnetic H-field component parallel to the axis of the slits). The origin of the slits transmission is attributed to plasmonic surface excitations. Our simulation results demonstrated that different cone angles originated from the Vshaped subwavelength slits generate different influences on the beam propagation. The width variation affects the optical transmission intensity significantly. Hopefully, exploring the influence on the light propagation behaviour through subwavelength apertures via theoretical simulations can provide a better understanding of the beam propagation phenomena for future studies.
A device consisting of a disk-shaped, Moiré-type plasmonic cavity placed inside a plasmonic crystal cavity, with a 250
nm polymethyl-methacrylate (PMMA) film over the cavities is analyzed by 3D finite-difference time domain (FDTD).
Both cavities can be fabricated by Focus Ion Beam, and the waveguide and the Moiré cavity contour can be defined by
one-step lithographic process. The device is characterized by calculating the cavity spectrum, the reflection and the
radiation spectra and the electric field intensity distribution. It was verified that the transverse-magnetic (TM) input
mode generates surface plasmon polaritons (SPP) at the PMMA/gold interface that excites localized surface plasmon
polariton on the Moiré cavity, that, in turn, generates reflected waves back to the waveguide and diffracted radiation.
Also, the lack of plasmonic crystal bandgap permits the evanescent coupling of Bloch waves to the plasmonic crystal.
The high electric field generated by the LSPP on the Moiré surface, and by the Bloch waves at the borders of the
plasmonic crystal holes, contributes to the fluorescence of molecules dissolved in the PMMA film. The radiated
fluorescence can be detected by a lensed fiber placed above the Moiré surface, and the reflected signal can be detected at
the output.
We report the 3D simulation of a disk-shaped, Moiré-type plasmonic cavity inside a photonic crystal cavity. The
simulation consider normal incidence of light over the sample to be analized with a confocal microscope in reflection
mode. The plasmonic cavity is made of gold, 250 nm of thickness, whose surface is modulated by a sinusoidal function.
The photonic crystal cavity is made in silicon nitride film (150 nm of thickness) over a SiO2 film (500 nm) on a silicon
substrate, the overall structure being Si/SiO2/SiN/Au. The simulation results show a three-fold enhancement of the
electric field intensity for the plasmonic cavity within the photonic cavity, in comparison with that for the plasmonic
cavity without the photonic crystal cavity. The result indicates that the electric field intensities of the photonic crystal
cavity modes add to the scattered field of the plasmonic cavity, thus enhancing the electric field just above the plasmonic
cavity. A preliminary test of the structure was done with a 300 nm gold film over a silicon substrate, made by focus ion
beam (FIB) milling, to show fluorescence enhancement of porphiryn molecules. The structure can be elaborated to serve
either as fluorescence enhancement of molecules or as Surface-enhancement Raman scattering (SERS) sensor.
Periodic nanostructure arrays forming electric dipoles or quadrupoles were fabricated with a Focused Gallium Ion Beam
on a gold thin film deposited onto an Er3+-doped tellurite glass. The nanostructures were vertically illuminated with an
Argon Ion laser (488 nm). The Er3+ luminescence spectrum was then measured in the far-field. The observed
luminescence is elucidated considering the following effects: (i) excitation of the Er3+ ions by means of the localized
surface plasmon resonance from the electric dipole/quadrupole nanostructures, that produce an improvement of the local
field, resulting in an enhanced luminescence, and (ii) the Er3+ luminescence spectrum depends on the albedo of the
system (electric dipole/quadrupole arrays), for which its resonant properties is strongly affected. In this way, the
emission of the Er3+ is achieved through the metallic nanostructures. Additional contributions for the observed emission
spectrum regarding the influence of physical and geometrical parameters, period of the electric multipole and lattice
symmetry have been investigated. The variation of these parameters resulted in a significantly improvement of
luminescence spectra.
Plasmonic lenses consisting of convex/concave concentric rings with different periods were milled with a Focused
Gallium Ion Beam on a gold thin film deposited onto an Er3+-doped tellurite glass. The plasmonic lenses were vertically
illuminated with an Argon Ion laser (488 nm) highly focused by means of a 20x objective lens. The focusing mechanism
of the plasmonic lenses is explained by using a simple coherent interference model of surface plasmon-polariton
generation on the circular grating as a result of the incident field. Particularly, this beam focusing structure has a
modulated groove depth (concave/convex). As a result, phase modulation can be accomplished by the groove depth
profile, similarly to a nano-slit array with different thicknesses. This focusing allows a high confinement of SPPs which
excited the Er3+ ions of the substrate. The luminescence spectrum of Er3+ ions was then measured in the far-field, where
we could verify the excitation yield of the plasmonic lens on the Er3+ ions. We analyze the influence of physical and
geometrical parameters on the emission spectra, such as the periodicity and depth profile of the rings. The variation of
these parameters resulted in considerable changes of the luminescence spectra.
Multilayered Ag/Au/Ag/Au and Au/Ag/Au/Ag films with 200 nm of thickness (50 nm for each layer) were evaporated
onto BK7 glass substrates. Sequences of slits (around 60-600 nm of width) were milled with a focused gallium ion beam
in the films. We have undertaken a series of high-resolution measurements of the optical transmission through the slits.
The transmission measurement setup consists of 488.0 nm (for the Ag/Au/Ag/Au film) and 632.8 nm (for the
Au/Ag/Au/Ag sample) wavelength light beams from Ar ion and HeNe lasers, respectively, aligned to the optical axis of a
microscope. The beam is focused onto the sample surface by a microscope objective in TM polarization (magnetic Hfield
component parallel to the long axis of the slits). As well, theoretical estimates investigating the slits optical
transmission were performed. The origin of the slits transmission is mainly attributed to plasmonic surface excitations.
Based on the present results, it was possible to observe that (1) the transmission increases linearly with increasing slit
width, and (2) the transmission of the multilayered structures is augmented in comparison with a single perforated metal
film of equal thickness, for a fixed slit width. A very good correspondence between theory and experiment was observed.
This work reports the fabrication of planar and channel waveguides by Ag+ → Na+ ion exchange in an Er3+ doped tellurite glass with a composition of 75TeO2-2GeO2-10Na2O-12ZnO-1Er2O3 (mol %). The glass was chemically stable during the ion-exchange process. We have been able to produce single and multi-mode planar waveguides controlling the depths of the waveguides by varying ion-exchange temperatures, from 250 to 280 °C, and times, from 3 to 12 h. We also show preliminary results of channel waveguide fabrication with the same technique. The waveguide effective refractive index curves and attenuation (11 dB/cm) at 1536 nm were measured with a Metricom prism coupler. The Amplified Spontaneous Emission (ASE) spectra showed a 152 nm bandwidth when pumped with 120 mW laser pump at 980 nm.
In this work we used a Thermal Mechanic Analysis equipment to produce the channel FOG waveguides by pressing an Er3+ doped tellurite glass optical fiber against one Er3+ ion doped tellurite glass substrate kept under Tc ± 30 oC (Tc = soft point). The luminescence and waveguide refractive index were measured. Scanning electron microscopy was used to observe the obtained structure. The objective is to produce a new concept in components of integrated optical circuits. Then this work report the production of Er3+-doped tellurite glass channel waveguides using the novel concept of Benson et al[1] of fiber on glass (FOG). To succeed with this technique it is important to correlate the main thermo-physical characteristics of the substrate and the fiber, which are the transition temperature Tg, the temperature of the onset of crystallization Tx, the maximum crystallization temperature Tc and the thermal expansion coefficient. The Tg, Tx and Tc values were determined by Differential Thermal Analysis (DTA), while the thermal expansion coefficient was determined by Thermal Mechanical Analysis (TMA). For the FOG purpose the thermal stability range, Tx - Tg, is an important temperature region which defines if the glass will have enough viscosity to shape in the FOG concept.
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