Leopoldo L. Martin

• PhD in Physics
• PostDoc Position at Instituto de Astrofísica de Canarias

A novel application of microresonators for refractometric sensing in aqueous media is presented. To carry out this approach, microspheres of different materials and sizes were fabricated and doped with Nd³⁺ ions. Under 532 nm excitation, the microspheres presented typical NIR Nd³⁺ emission bands with superimposed sharp peaks, related to the Whisper...

This study experimentally and numerically validates the commonly employed technique of laser-induced heating of a material in optical temperature sensing studies. Furthermore, the Er3+-doped glass microspheres studied in this work can be employed as remote optical temperature sensors. Laser-induced self-heating is a useful technique commonly employ...

Featured Application The investigated YAS glass microspheres doped with Nd³⁺ ions have great potential as remote optical temperature sensors. Moreover, they are suitable for the development of laser devices with low power thresholds. Abstract Yttria–alumina–silica (YAS) glass microspheres doped with Nd³⁺ ions were excited with a 532 nm continuous...

Degeneracies play a crucial rule in precise scientific measurements as well as in sensing applications. Spherical resonators have a high degree of degeneracy thanks to their highest symmetry; yet, fabricating perfect spheres is challenging because even a stem to hold the sphere breaks the symmetry. Here we fabricate a levitating spherical resonator...

Glass microspheres embedded with Nd³⁺‐doped nanoperovskites based on yttrium orthoaluminate are synthesized and used as optical vacuum sensor. Under 532 nm excitation, the microspheres show two emission bands centered at 820 and 890 nm, corresponding to the ²H9/2,⁴F5/2 → ⁴I9/2 and ⁴F3/2 → ⁴I9/2 transitions. When the microspheres are heated by laser...

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with solid-cladding devices, capillary oscillations are not restricted, allowing the fiber walls to move and vibrate. The fiber is constructed by a high direct current (DC) voltage of several thousand volt...

We experimentally demonstrate light-flow interaction, in which the angular momentum of circulating light excites micro-vortices. In contrast with the solid-phase of matter, where one has to overcome static friction in order to start motion, liquids have no “static drag.” Relevant to almost all optofluidic micro-systems hence, μWatt optical power is...

The confinement of light and sound, while they are traveling in fibers, enables a variety of light-matter interactions. Therefore, it is natural to ask if fibers can also host capillary waves. Capillary waves are similar to those we see when throwing a stone into a puddle. Such capillary waves are prohibited in microfluidic devices where the liquid...

We experimentally demonstrate the high sensitivity of a novel liquid state, whispering-gallery-mode optical resonator to humidity changes. The optical resonator used consists of a droplet made of glycerol, a transparent liquid that enables high optical quality factor, doped with fluorescent material. As glycerol is highly hygroscopic, the refractiv...

Lasers rely on stimulated electronic transition, a quantum phenomenon in the form of population inversion. In contrast, phonon masers depend on stimulated Raman scattering and are entirely classical. Here we extend Raman lasers to rely on capillary waves, which are unique to the liquid phase of matter and relate to the attraction between intimate f...

The Shockley-Queisser efficiency limit of ~40% for single-junction photovoltaic (PV) cells is mainly caused by the heat dissipation accompanying the process of electro-chemical potential generation. Concepts such as solar thermo-photovoltaics (STPV) aim to harvest this heat loss by the use of a primary absorber which acts as a mediator between the...

Fibers constitute the backbone of modern communication and are used in laser surgeries; fibers also genarate coherent X-ray, guided-sound and supercontinuum. In contrast, fibers for capillary oscillations, which are unique to liquids, were rarely considered in optofluidics. Here we fabricate fibers by water bridging an optical tapered-coupler to a...

We fabricate a liquid-core liquid-clad microcavity that is coupled to a standard tapered fiber, and then experimentally map the whispering-gallery modes of this droplet resonator. The shape of our resonator is similar to a thin prolate spheroid, which makes space for many high-order transverse modes, suggesting that some of them will share the same...

Droplets, particularly water droplets, are abundant in both natural and artificial systems. Their capillary oscillations are governed by surface tension and are therefore distinguished from acoustic oscillations. These capillary oscillations play a major role in droplet coalescence, for example, and are also an important phenomenon in interface the...

We fabricate a liquid-core liquid-clad microcavity that is coupled to a standard tapered fiber, and then experimentally map the whispering-gallery modes of this droplet resonator. The shape of our resonator is similar to a thin prolate spheroid, which makes space for many high-order transverse modes, suggesting that some of them will share the same...

Energy exchange between light and sound was first suggested by Brillouin in 1922. After Townes established the phonon maser theory, coherent generation of intense hypersonic waves was observed together with stimulated Brillouin Scattering. Here we repeat these experiments, but with capillary-waves that are unique to the liquid phase of matter and r...

This publisher’s note amends a recent publication [Opt. Express 24(3), 2850–2857 (2016)] to include Acknowledgments.

We experimentally demonstrate the use of a novel liquid state, whispering-gallery-mode optical resonator as a highly sensitive humidity sensor. The optical resonator used consists of a droplet made of glycerol, a transparent liquid that enables high optical quality factor, doped with rhodamine 6G, which acts as fluorescent emitter. As glycerol is h...

Unlike capillary resonance by Rayleigh (Proc. R. Soc. London 29, 71 (1879)PRSLAZ0370-166210.1098/rspl.1879.0015) and optical resonance by Ashkin (Phys. Rev. Lett. 38, 1351 (1977)PRLTAO0031-900710.1103/PhysRevLett.38.1351), acoustic resonance in fluid droplets has rarely been studied. Here we use droplets and optically excite and interrogate their a...

We experimentally reporton optical binding of many glass particles in air that levitate in a single optical beam. A diversity of particle sizes and shapes interact at long range in a single Gaussian beam. Our system dynamics span from oscillatory to random and dimensionality ranges from 1 to 3D. The low loss for the center of mass motion of the bea...

In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 r...

Supplementary Figure 1, Supplementary Notes 1-3, Supplementary Methods and Supplementary References.

Fabrication of a water-walled microfluidic (slowed down by a factor of 8)

Vaporization of control-group water droplets that are sprayed on a resolution target (real time).

We experimentally demonstrate trapping a microdroplet by using an optical tweezer and then activating it as a microresonator by bringing it close to a tapered-fiber coupler. Our tweezers facilitated the tuning of the coupling from the under-coupled to the critically-coupled regime while the quality-factor [Q] is 12 million and the resonator’s size...

Contrary to their capillary resonances (Rayleigh, 1879) and their optical resonances (Ashkin, 1977), droplets acoustical resonances were rarely considered. Here we experimentally excite, for the first time, the acoustical resonances of a droplet that relies on sound instead of capillary waves. Droplets vibrations at 37 MHz rates and 100 quality fac...

Liquids serve microcavity research ever since Ashkins studies on optical resonances in levitating droplets to recent optofluidic resonators. Droplets can provide optical quality factor (Q) in proximity to the limit restricted by water absorption and radiation loss. However, water micro-drops vaporize quickly due to their large area to volume ratio....

We demonstrate a new type of optical MEMS that is having most of its walls made of liquids. Examples include (1) experimental demonstration of water-walled microfluidic devices with optical finesse over a million as well as (2) cavity optomechanics at 40 MHz vibrational rates in a droplet of oil

Photoluminescence (PL) is a fundamental light–matter interaction that conventionally involves the absorption of an energetic photon, thermalization, and the emission of a redshifted photon. Conversely, in optical refrigeration, the absorption of a low-energy photon is followed by endothermic PL of an energetic photon. These two quantum processes ar...

We experimentally demonstrate, for the first time, binding of aerosols of various sizes and shapes in white light. The optomechancial interaction between particles is long range and is in the underdamped regime. Incoherency allows mitigation of interference fringes to enable monotonically changing the distance between particles from 60 μm to contac...

Photoluminescence (PL) is a fundamental light-matter interaction, which conventionally involves the absorption of energetic photon, thermalization and the emission of a red-shifted photon. Conversely, in optical-refrigeration the absorption of low energy photon is followed by endothermic-PL of energetic photon. Both aspects were mainly studied wher...

Improving the conversion efficiency of solar energy to electricity is most important to mankind. For single-junction photovoltaic solar-cells, the Shockley-Queisser thermodynamic efficiency limit is extensively due to the heat dissipation, inherently accompanying the quantum process of electro-chemical potential generation. Concepts such as solar t...

The effects of pressure on the behavior of optical microspherical resonators, prepared from doped, barium titanium silicate glass, have been studied up to 5 GPa inside a diamond anvil cell using silicone oil as the hydrostatic transmission medium and ruby emission lines as the pressure gauge. The optical resonances, known as whispering gallery mode...

We experimentally demonstrate clustering of spherical and non-spherical aerosols in a smooth optical-tweezers. Our empty trap has only a single local-minimum with additional minima being born by the aerosols that join the trap.

Laser action using non-coupled excitation and detection of microspheres made of Nd3+ doped barium–titanium–silicate glass has been demonstrated and measured. The microspheres have also been successfully deposited over Si3N4 strip waveguides with a SiO2 separation layer, thus enabling the laser emission extraction onto a CMOS compatible photonic cir...

form only given. The upconversion emission properties of Er3+-Yb3+ and Tm3+-Yb3+ codoped glass and glass ceramic samples covered with silica microspheres (3.8 μm diameter) were analyzed. A 950 nm laser beam focused by the microspheres produces a set of photonic nanojets on the sample surface. Due to upconversion processes, the optically active ions...

An intensity enhancement of the green upconversion emission from a codoped Er³⁺ -Yb³⁺ fluoroindate glass has been obtained by coating the glass surface with silica microspheres (3.8 µm diameter). The microspheres focus an incoming beam (λ ≈950 nm) on the surface of the fluoroindate glass. The green emission (λ ≈545 nm) of the Er³⁺ ions located in t...

Two different thermal treatments were used to create nanocrystals from a precursor glass. The glass whose composition is Ba2TiSi2O8 and doped with 3% of Nd3+ was prepared using the melt quenching method. A conventional thermal treatment in an electrical furnace was used to obtain transparent glass ceramic samples, which contain Fresnoite nanocrysta...

We present the optical characterization of single light emitting glass microspheres by means of an experimental setup that combines -transmission and -photoluminescence measurements without the need of optical fibers for excitation or detection purposes. We demonstrate that the results provided by both techniques are consistent among them and can p...

Microspheres of Nd³⁺ doped barium titano silicate glass were prepared and the whispering gallery mode resonances were observed in a modified confocal microscope. A bulk sample of the same glass was calibrated as temperature sensor by the fluorescence intensity ratio technique. After that, the microsphere was heated by laser irradiation process tech...

The synthesis of Eu3+ doped titania nanotubes was carried out via a hydrothermal method. X-ray diffraction and transmission electron microscope analyses showed that the nanotubes were formed by rolling multilayered titania structure with a length of up to 100 nm. The Eu3+-doped nanotubes exhibited strong emission lines associated with the 5D0→7FJ (...

The forward and backward energy transfer processes in Strontium Barium Niobate glass-ceramics double doped with Yb3+ and Er3+ ions have been studied. In these samples the rare earth ions are incorporated into the nanocrystals with an average size of 50nm. Using laser excitation at 950nm is possible to excite selectively the Yb3+ ions and detect emi...

Photoluminescence measurements have been performed on glass ceramic samples of strontium barium niobate doped with Er(3+). The glass-ceramic samples were obtained from the precursor glass by thermal treatment and were doped with different contents of Er(3+) ions. The average size of the nanocrystals in the samples was about 50 nm. The optical prope...

Export Date: 24 May 2012, Source: Scopus

Comparative investigation of the optical amplification properties of dysprosium doped Gd2SiO5, Lu2SiO5 and YAl3(BO3)4 single crystals was performed in a pump-and-probe experiment. High power laser pulses at 475 nm were used as the pump source in order to strongly populate the 4F9/2 level of the Dy3+ ions due to ground state absorption. Low signal b...

Temperature sensor is a vast group of the commercially approachable optical sensors. Recently has appeared a new kind of these devices using the fluorescence intensity ratio (FIR) with a very good sensitivity. The FIR technique has been carried out in Strontium Barium Niobate (SBN) glass ceramic sample to extend the knowledge of this kind of matrix...

Cited By (since 1996): 1, Export Date: 24 May 2012, Source: Scopus

Whispering-gallery modes (WGMs) on Nd 3 + -doped glass microspheres with a radius of ∼ 15 μm were measured in a modified confocal microscope, where a dual spatial resolution in both excitation and detection zones was possible. As an alternative to the standard excitation mechanism by an evanescent wave, we used an efficient pumping/ detecting schem...

Usually the Dy(3+) ions have been used as laser sources associated with the (6)H(13/2) -> (6)H(15/2) transition about 3 mu m. However, these ions exhibit emissions in the blue (480 nm) and in the yellow (575 nm) that are promising for laser operations. In this work, positive optical gain about 1.9 cm(-1) (similar to 8.2 dB/cm) has been observed at...

The Ba2TiSi2O8 (BTS) is a well known piezoelectric, ferroelectric and non-linear crystal. In this work, nanocrystals of BTS have been obtained by different thermal treatments of precursor glasses. The glasses were fabricated from BaO–TiO2–SiO2 and doped with Dy2O3 using the melt quenching method. Thermal treatment in an electrical furnace at 740 °C...

The study of two different methods to obtain Strontium Barium Niobate nanocrystals has been carried out. Previously, Nd2O3 doped SrO-BaO-Nb2O5-B2O3 glasses were fabricated using the melt quenching process. In the first method, a thermal treatment in an electrical furnace at 620 degrees C was used to obtain glass ceramic samples. In the second one,...

An appropriated thermal treatment of SrO–BaO–Nb2O5–B2O5 glass leads to the formation of glass ceramics which are composed of Tm3+–Yb3+ codoped strontium barium niobate (SBN) nanocrystals dispersed throughout an amorphous matrix. The glasses have been fabricated using a melt-quenching method and after a thermal treatment at 620 °C have been obtained...

IntroductionExperimentalResults and DiscussionConclusions Acknowledgements

Localized modification of the optical properties of erbium doped strontium barium niobate (SBN) glass has been performed using femtosecond laser irradiation. The samples, with composition SrO–BaO–Nb2O5–B2O5 and doped with 5%mol of Er3+, were fabricated using a melt-quenching method. The samples were irradiated with different number of pulses per sp...

Cited By (since 1996): 2, Export Date: 24 May 2012, Source: Scopus

On September 8, 2001 around 2 h UT, the largest uranian moon, Titania, occulted Hipparcos star 106829 (alias SAO 164538, a V=7.2, K0 III star). This was the first-ever observed occultation by this satellite, a rare event as Titania subtends only 0.11 arcsec on the sky. The star's unusual brightness allowed many observers, both amateurs or professio...