Showing papers in "Applied Physics B in 2007"
TL;DR: The dependence of temperature on the fluorescence lifetime and fluorescence intensity ratio using Stark sublevels and thermally coupled (close lying) levels in triply ionized rare earth ions, doped into a variety of glasses and fibers, have been reviewed in this article.
Abstract: The dependence of temperature on the fluorescence lifetime and fluorescence intensity ratio using Stark sublevels and thermally coupled (close lying) levels in triply ionized rare earth ions, doped into a variety of glasses and fibers, have been reviewed. Also, it is claimed that not only for the two closely lying levels of triply ionized rare earth ion of the same kind, but also for two different triply ionized rare earth ions, having their excited levels very close to each other, may be used to monitor the temperature.
319 citations
TL;DR: In this article, femtosecond stimulated Raman microscopy (FSRM) is introduced, which is a non-linear nonlinear Raman imaging method that uses femtocond white light pulses and intense picosecond pulses derived from a femto-cond laser/amplifier system.
Abstract: A novel type of non-linear Raman microscopy, femtosecond stimulated Raman microscopy (FSRM), is introduced. It employs femtosecond white light pulses and intense picosecond pulses which are derived from a femtosecond laser/amplifier system. The pulses are coupled into a microscope set-up and induce a stimulated Raman process at the focus. The Raman interaction spectrally modulates the white light. These modulations are read-out in multi-channel fashion and allow recording of a complete Raman spectrum of the focal region. By raster-scanning the sample, complete Raman images can be obtained. Raman images of polystyrene beads in water demonstrate the feasibility of the approach.
293 citations
TL;DR: A detailed overview of the so far presented OCT-based methods and applications, ranging from dimensional metrology, material research and non-destructive testing, over art diagnostics, botany, microfluidics to data storage and security applications, and include new data from a study on penetration depths in various polymer materials.
Abstract: Optical coherence tomography (OCT), a method for depth-resolved imaging within turbid media based on the concept of low-coherence interferometry, rapidly evolved in the recent years with the development of a multitude of new functionalities and modalities. Biomedical research and diagnostics have been up to now the main driving forces for the reported applications and progress in OCT. The characteristics of OCT, precisely the ability to provide high-resolution images in a contact-free way, render this technique also attractive for a broad spectrum of research topics and applications outside the biomedical field. Consequently, a variety of novel applications for OCT and developments for the method itself have started to emerge. In this review we will give a detailed overview of the so far presented OCT-based methods and applications, ranging from dimensional metrology, material research and non-destructive testing, over art diagnostics, botany, microfluidics to data storage and security applications, and include new data from a study on penetration depths in various polymer materials as well as on birefringence imaging of different crystalline polymer structures. Finally, advanced and related OCT techniques are presented with high potential for future applications outside the biomedical field.
284 citations
TL;DR: In this paper, the compensation of loss in metal by gain in interfacing dielectric has been demonstrated in a mixture of aggregated silver nanoparticles and rhodamine 6G dye, and an increase of the quality factor of surface plasmon resonance was evidenced by the sixfold enhancement of Rayleigh scattering.
Abstract: The compensation of loss in metal by gain in interfacing dielectric has been demonstrated in a mixture of aggregated silver nanoparticles and rhodamine 6G dye. An increase of the quality factor of surface plasmon (SP) resonance was evidenced by the sixfold enhancement of Rayleigh scattering. The compensation of plasmonic losses with gain enables a host of new applications for metallic nanostructures, including low- or no-loss negative-index metamaterials. We have also predicted and experimentally observed a suppression of SP resonance in metallic nanoparticles embedded in dielectric host with absorption.
264 citations
TL;DR: In this article, the authors present a discussion of the key aspects of a table-top FEL design, including energy loss and chirps induced by space-charge and wakefields.
Abstract: A recent breakthrough in laser-plasma accelerators, based upon ultrashort high-intensity lasers, demonstrated the generation of quasi-monoenergetic GeV-electrons. With future Petawatt lasers ultra-high beam currents of ∼100 kA in ∼10 fs can be expected, allowing for drastic reduction in the undulator length of free-electron-lasers (FELs). We present a discussion of the key aspects of a table-top FEL design, including energy loss and chirps induced by space-charge and wakefields. These effects become important for an optimized table-top FEL operation. A first proof-of-principle VUV case is considered as well as a table-top X-ray-FEL which may also open a brilliant light source for new methods in clinical diagnostics.
220 citations
TL;DR: In this article, a comparison of ten models that predict the temporal behavior of laser-induced incandescence (LII) of soot was performed for a single primary particle with a diameter of 30 nm at an ambient temperature of 1800 K and a pressure of 1 bar.
Abstract: We have performed a comparison of ten models that predict the temporal behavior of laser-induced incandescence (LII) of soot. In this paper we present a summary of the models and comparisons of calculated temperatures, diameters, signals, and energy-balance terms. The models were run assuming laser heating at 532 nm at fluences of 0.05 and 0.70 J/cm(2) with a laser temporal profile provided. Calculations were performed for a single primary particle with a diameter of 30 nm at an ambient temperature of 1800 K and a pressure of 1 bar. Preliminary calculations were performed with a fully constrained model. The comparison of unconstrained models demonstrates a wide spread in calculated LII signals. Many of the differences can be attributed to the values of a few important parameters, such as the refractive-index function E(m) and thermal and mass accommodation coefficients. Constraining these parameters brings most of the models into much better agreement with each other, particularly for the low-fluence case. Agreement among models is not as good for the high-fluence case, even when selected parameters are constrained. The reason for greater variability in model results at high fluence appears to be related to solution approaches to mass and heat loss by sublimation.
204 citations
TL;DR: In this article, a two-color far-field fluorescence microscopy with nanoscale spatial resolution based on the photoswitching of individual fluorescent markers was demonstrated, where the position of individual emitters was determined with a typical accuracy of 20 nm.
Abstract: We demonstrate two-color far-field fluorescence microscopy with nanoscale spatial resolution based on the photoswitching of individual fluorescent markers. By enabling, recording, and disabling the emission of the reversibly switchable fluorescent protein rsFastLime and of the organic fluorophore cyanine5, we recorded two-color nanoscale images inside whole cells. The position of individual emitters was determined with a typical accuracy of 20 nm, which largely constitutes the lateral resolution of the system. Photoswitching in two-color colocalization experiments represents a major step towards the application of far-field fluorescence nanoscopy to the study of (biological) samples on the macromolecular level.
162 citations
TL;DR: In this article, the etch performance of amorphous Al2O3 and polycrystalline Y 2O3 films has been investigated using an inductively coupled reactive ion etch system.
Abstract: Etching of amorphous Al2O3 and polycrystalline Y2O3 films has been investigated using an inductively coupled reactive ion etch system. The etch behaviour has been studied by applying various common process gases and combinations of these gases, including CF4/O2, BCl3, BCl3/HBr, Cl2, Cl2/Ar and Ar. The observed etch rates of Al2O3 films were much higher than Y2O3 for all process gases except for Ar, indicating a much stronger chemical etching component for the Al2O3 layers. Based on analysis of the film etch rates and an investigation of the selectivity and patterning feasibility of possible mask materials, optimized optical channel-waveguide structures were fabricated in both materials. In Al2O3, channel waveguides were fabricated with BCl3/HBr plasma and using a standard resist mask, while in Y2O3, channel waveguides were fabricated with Ar and using either a resist or a sputter deposited Al2O3 mask layer. The etched structures in both materials exhibit straight sidewalls with minimal roughness and sufficient etch depths (up to 530 nm for Al2O3 and 250 nm for Y2O3) for defining waveguides with strong optical confinement. Using the developed etch processes, low additional optical propagation losses (on the order of 0.1 dB/cm) were demonstrated in single-mode ridge waveguides in both Al2O3 and Y2O3 layers at 1550 nm.
148 citations
TL;DR: In this article, the average irradiance of phase-locked and non-phase-locked radial and rectangular laser array beams is derived through vector integration and tensor operation, and the irradiance properties of these laser arrays in a turbulent atmosphere are studied numerically.
Abstract: The propagation of phase-locked and non-phase-locked laser array beams of radial and rectangular symmetries in a turbulent atmosphere are investigated based on the extended Huygens–Fresnel integral. The beamlet used in our paper for constructing the laser array beams is of elliptical Gaussian mode. Analytical formulae for the average irradiance of phase-locked and non-phase-locked radial and rectangular laser array beams are derived through vector integration and tensor operation. The irradiance properties of these laser array beams in a turbulent atmosphere are studied numerically. It is found that both phase-locked and non-phase-locked radial and rectangular laser array beams eventually become circular Gaussian beams in a turbulent atmosphere, which is much different from their propagation properties in free space. The propagation properties are closely related to the parameters of laser array beams and the structure constant of the turbulent atmosphere.
129 citations
TL;DR: In this article, a mode converter that transforms a plane electromagnetic wave into an inward-moving dipole wave is described, which is intended to bring a single atom or ion from its ground state to an excited state by absorption of a single photon wave packet with near-100% efficiency.
Abstract: In this article, we describe how to develop a mode converter that transforms a plane electromagnetic wave into an inward-moving dipole wave. The latter one is intended to bring a single atom or ion from its ground state to an excited state by absorption of a single photon wave packet with near-100% efficiency.
121 citations
TL;DR: In this paper, the authors demonstrate numerically and experimentally a chirped mirror with controlled reflectivity and dispersion of up to 1.5 octaves, with residual group delay dispersion ripples <100 fs2 in all of this range.
Abstract: We demonstrate numerically and experimentally a chirped mirror with controlled reflectivity and dispersion of up to 1.5 octaves. A complementary pair of such mirrors has a reflectivity of 95% in the wavelength range 400–1200 nm with residual group delay dispersion ripples <100 fs2 in all of this range. The mirror pair allows one to compensate a chirp of the corresponding spectrum (with a smooth phase), resulting in sub-3-fs pulses.
TL;DR: In this article, the relative values of the elements of the second-order susceptibility tensor of Fe(IO3)3 were determined by the global fitting of the polarization-resolved second harmonic generation (SHG) response of an ensemble of nanocrystals.
Abstract: We have investigated nanocrystals of Fe(IO3)3 by polarization-sensitive second harmonic generation (SHG) microscopy. As the nonlinear optical properties of this material were only poorly characterized, we have first determined the relative values of the elements of its second-order susceptibility tensor, by the global fitting of the polarization-resolved SHG response of an ensemble of nanocrystals. This information allows one to optically retrieve the orientation of individual particles in the sample. The high SHG efficiency measured for nanocrystals of Fe(IO3)3 and their polar nature could make them very attractive for nonlinear microscopy of biological samples.
TL;DR: In this paper, the authors employed a continuous wave thermoelectrically cooled, distributed feedback diode laser operating at 2 μm for trace gas concentration measurements of CO2 and NH3.
Abstract: Quartz-enhanced photoacoustic spectroscopy was employed for trace gas concentration measurements of CO2 and NH3 using a continuous wave thermoelectrically cooled, distributed feedback diode laser operating at 2 μm. A normalized noise equivalent absorption coefficient, NNEA(1σ)=1.4×10-8 cm-1W/\(\sqrt{\text{Hz}}\) was obtained for CO2 using the R18 line of the 2ν1+ν3 band at 4991.26 cm-1. This corresponds to minimum detection limit (1σ) of 18 parts per million (ppm) for a 1 s lock-in time constant. The influence of the H2O presence in the sample gas mixture on the CO2 sensor performance was investigated. Ammonia detection was performed using the PP6(6)S line of the ν3+ν4 band at 4986.99 cm-1. A detection limit (1σ) of 3 ppm for NH3 concentration with a 1 s lock-in time constant was achieved. This results in a normalized noise equivalent absorption of NNEA(1σ)=8.9×10-9 cm-1W/\(\sqrt{\text{Hz}}\).
TL;DR: In this article, various experimental realizations to produce ultra-short terahertz (THz) radiation in bulk, periodically, aperiodically and two-dimensionally poled LN are discussed.
Abstract: Optical rectification of femtosecond pulses in nonlinear materials is an efficient method to generate ultra-short terahertz (THz) pulses in a wide frequency range extending from 100 GHz to well above 10 THz. Lithium niobate (LN) is well suited for such a purpose despite the high absorption in the THz range. In this part we will focus on the various experimental realizations to produce THz radiation in bulk, periodically, aperiodically and two-dimensionally poled LN. The possible bandwidth, tunability and the techniques to overcome the high absorption will be discussed as well.
TL;DR: In this article, the third order nonlinear optical properties of 4′-methoxy chalcone and its derivatives were investigated using a single-beam Z-scan technique with nanosecond laser pulses at 532 nm.
Abstract: The third order nonlinear optical properties of 4′-methoxy chalcone and its derivatives have been investigated using a single-beam Z-scan technique with nanosecond laser pulses at 532 nm. The 4′-methoxy chalcone and its derivatives are donor–acceptor–acceptor (D–A–A) and donor–acceptor–donor (D–A–D) type intramolecular charge transfer molecules. The nonlinear response in these molecules was found to increase with increase in (a) the electron acceptor strength in D–A–A type and (b) the donor strength of the substituted group in D–A–D type molecules. The χ(3) value in these molecules is found to be of the order of 10-13 esu. The observed increase in the third order nonlinearity in these molecules clearly indicates the electronic origin. The compounds exhibit good optical limiting at 532 nm. The best optical limiting behavior was observed with the molecule substituted by a strong electron donor.
TL;DR: In this article, a fast response (100 kHz) tunable diode laser absorption sensor is developed for measurements of temperature and H2O concentration in shock tubes, e.g. for studies of combustion chemistry.
Abstract: A fast-response (100 kHz) tunable diode laser absorption sensor is developed for measurements of temperature and H2O concentration in shock tubes, e.g. for studies of combustion chemistry. Gas temperature is determined from the ratio of fixed-wavelength laser absorption of two H2O transitions near 7185.60 cm-1 and 7154.35 cm-1, which are selected using design rules for the target temperature range of 1000–2000 K and pressure range of 1–2 atm. Wavelength modulation spectroscopy is employed with second-harmonic detection (WMS-2f) to improve the sensor sensitivity and accuracy. Normalization of the second-harmonic signal by the first-harmonic signal is used to remove the need for calibration and minimize interference from emission, scattering, beam steering, and window fouling. The laser modulation depth for each H2O transition is optimized to maximize the WMS-2f signal for the target test conditions. The WMS-2f sensor is first validated in mixtures of H2O and Ar in a heated cell for the temperature range of 500–1200 K (P=1 atm), yielding an accuracy of 1.9% for temperature and 1.4% for H2O concentration measurements. Shock wave tests with non-reactive H2O–Ar mixtures are then conducted to demonstrate the sensor accuracy (1.5% for temperature and 1.4% for H2O concentration) and response time at higher temperatures (1200–1700 K, P=1.3–1.6 atm).
TL;DR: In this article, the authors derived analytical expressions for the fields of a tightly focused Gaussian laser beam and found that using the derived fields, the calculated power can be about 25% more accurate than when calculated using the paraxial approximation for a beam focused down to a waist radius w 0∼0.4λ, where λ is the wavelength.
Abstract: Analytic expressions for the fields of a tightly focused Gaussian laser beam are derived, accurate to e11, where e is the diffraction angle. It is found that, for example, using the derived fields, the calculated power can be about 25% more accurate than when calculated using the paraxial approximation for a beam focused down to a waist radius w0∼0.4λ, where λ is the wavelength.
TL;DR: In this paper, the authors use optical modeling to quantitatively calculate the dissipation in each of the various layers as functions of wavelength and layer thickness, and use this information the loss free short circuit current density can be calculated (Jscmax).
Abstract: The efficiency that a solar cell can reach is ultimately limited by the number of photons absorbed in its active layer. Bulk heterojunction polymer solar cells are fabricated from a stack of thin film layers, each of which is thinner than a single wavelength from an incident photon within its absorption band. One consequence of this thin film layer stack is a strong optical interference between the various layers that can change the quantity of light dissipated in the active layer by 50%. Here we use optical modeling to quantitatively calculate the dissipation in each of the various layers as functions of wavelength and layer thickness. Using this information the loss free short circuit current density can be calculated (Jscmax). Optimization of Jscmax leads to direct improvements in the efficiency of the solar cell through improved light dissipation in the active layer. The optical properties for a P3HT:PCBM active layer and a model Lorentzian low band gap spectrum are optimized and ideal fabrication conditions are reported for these materials.
TL;DR: In this article, a femtosecond laser pulse self-stabilizes the intensity fluctuation inside the filament core due to intensity clamping and generates an excellent spatial beam quality inside the core.
Abstract: A filamenting femtosecond laser pulse self-stabilizes the intensity fluctuation inside the filament core due to intensity clamping and generates an excellent spatial beam quality inside the core due to self-spatial filtering. The high quality of the core can be sampled by nonlinear processes. A few experimental examples are shown: self-phase modulation, four-wave mixing, third-harmonic generation and waveguide writing in glass.
TL;DR: In this paper, the authors demonstrated the feasibility of remote detection and differentiation of some very similar agricultural-activity related bioaerosols, namely barley, corn, and wheat grain dusts, through nonlinear fluorescence of fragments induced by the high-intensity inside filaments of femtosecond laser pulses in air.
Abstract: We demonstrated the feasibility of remote detection and differentiation of some very similar agricultural-activity related bioaerosols, namely barley, corn, and wheat grain dusts, through nonlinear fluorescence of fragments induced by the high-intensity inside filaments of femtosecond laser pulses in air. The signals were detected in Lidar configuration with targets located at 4.7 m away from the detection system. All the species showed identical spectra, namely those from molecular C2 and CN bands, as well as atomic Si, C, Mg, Al, Na, Ca, Mn, Fe, Sr and K lines. These identical spectral bands and lines reveal similar chemical compositions; however, the relative intensities of the spectra are different showing different element abundances from these three bio-targets. The intensity ratios of different elemental lines were used to distinguish these three samples. Good reproducibility was obtained. We expect that this technique could be used at long distance and thus played as a sensor of similar biological hazards for public and defense security.
TL;DR: In this article, images and emission spectra of sparks produced by laser-induced breakdown in air were investigated with a high degree of spatial and temporal resolution using a framing intensified charged coupled device (CCD) camera and a multi-fiber Cassegrain optics system coupled to an intensified CCD spectrometer.
Abstract: Images and emission spectra of sparks produced by laser-induced breakdown in air were investigated with a high degree of spatial and temporal resolution. The laser-induced breakdown was generated by focusing a 532-nm nanosecond pulse from a Q-switched Nd:YAG laser. The data were collected using a framing intensified charged coupled device (CCD) camera and a multi-fiber Cassegrain optics system coupled to an intensified CCD spectrometer. The results provided information about the different stages of laser-induced breakdown. The plasma shape and emission spectrum were very reproducible. Different ionization levels in the plasma kernels, which were observed using the high spatial resolution of the multi-fiber Cassegrain optics system, occurred during the plasma formation and cooling and at different locations within the plasma. This was due mainly to the thickness of the plasma relative to the laser wavelength, which created different ionization levels and energy absorption rates throughout. These observations were correlated with the plasma visualizations obtained with the framing ICCD camera. The plasma emission analysis permitted us to study the temperature evolution along the plasma during the laser-induced breakdown process. The analysis demonstrated the validity of a laser-supported wave model during the first stages of laser-induced breakdown and illustrated the weak dependence of the plasma temperature on the input energy.
TL;DR: In this paper, the spectroscopic properties and room-temperature cw tunable laser operation of Yb3+-doped CaF2, SrF2 and BaF2 single crystals grown and studied in the same conditions are compared.
Abstract: We present the spectroscopic properties and room-temperature cw tunable laser operation of Yb3+-doped CaF2, SrF2 and BaF2 single crystals grown and studied in the same conditions. Emission cross sections, lifetimes, laser thresholds, laser slope efficiencies and laser wavelength tuning ranges are compared. It appears that Yb3+-doped BaF2 might be more promising for diode-pumped high power laser operation.
TL;DR: In this paper, a photoacoustic cell was used to detect carbon dioxide (CO2) at 1572 nm with a distributed feedback diode laser, achieving a normalized noise equivalent sensitivity of 1.7×10-10 cm-1W/\(\sqrt{Hz}) at atmospheric pressure.
Abstract: Recently introduced cantilever enhanced photoacoustic sensing has been applied to the tunable diode laser-based trace gas detection. The pressure variations due to the photoacoustic signal are detected with a miniature silicon cantilever, whose displacement is measured with a compact Michelson type laser interferometer. The system has been used to detect carbon dioxide (CO2) at 1572 nm with a distributed feedback diode laser. With a new photoacoustic cell, that was optimized for the laser sources, a normalized noise equivalent sensitivity of 1.7×10-10 cm-1W/\(\sqrt{Hz}\) at atmospheric pressure was realized. The result obtained in the non-resonant operation mode is at least 10 times better than in previous reports. The future improvements of the technique are also discussed.
TL;DR: In this paper, the propagation characteristics of higher order Bessel-Gaussian beams travelling in turbulent atmosphere are investigated using extended Huygens-Fresnel principle, using receiver plane intensity and solved it down to a double integral stage.
Abstract: The propagation characteristics of higher order Bessel–Gaussian beams travelling in turbulent atmosphere are investigated. Using extended Huygens–Fresnel principle, I formulated receiver plane intensity and solved it down to a double integral stage. Source beam plots are made illustrating the variation of intensity against order and width parameter. From the examination of receiver intensity graphs, it is seen that Bessel–Gaussian beam are converted into modified Bessel–Gaussian beams at intermediate propagation ranges eventually ending up as Gaussian profiles. The impacts of order and turbulence levels on beam profile are analysed. Focusing effects and beam size change along the propagation axis are studied.
TL;DR: In this paper, the origins and suppression of the large frequency jitter on the carrier-envelope offset frequency (fceo) of fiber-laser frequency combs are discussed.
Abstract: We discuss the origins and the suppression of the large frequency jitter on the carrier-envelope offset frequency (fceo) of fiber-laser frequency combs. While this frequency noise appears most prominently on fceo, its effects are felt across the frequency comb and it is a potential limiting factor in applications of fiber-laser frequency combs. Here we show that its origin lies in the white amplitude noise of the pump laser output. We dramatically reduce this noise by operating the pump laser in a lower-noise state, i.e. at higher pump current, and by more aggressively feeding back to the pump current with an optimal feedback network. We demonstrate instrument-limited fceo linewidths and an integrated fceo phase jitter of 1 rad.
TL;DR: In this article, the authors proposed a new compact and reliable laser system for rubidium laser cooling in onboard experiments like atomic clocks or atomic inertial sensors based on the frequency doubling of a telecom fiber bench at 1560-nm.
Abstract: We propose a new compact and reliable laser system for rubidium laser cooling in onboard experiments like atomic clocks or atomic inertial sensors The system is based on the frequency doubling of a telecom fiber bench at 1560 nm Fiber components at 1560 nm allow us to generate the repumping laser and to control dynamically the power and the frequency of the 780 nm laser With this laser system, we obtain a magneto-optical trap of 85Rb even in the presence of mechanical vibrations and strong thermal variations (12 °C in 30 min)
TL;DR: In this paper, the optical concentration of a cylindrical luminescent solar concentrator (LSC) is compared to that of a more conventional square-planar LSC.
Abstract: The optical concentration of a cylindrical luminescent solar concentrator (LSC) is compared to that of the more conventional square-planar LSC. It is found that when luminescence occurs close to the surface the optical concentration of a cylindrical LSC is 1.0–1.9 times higher than that of a square-planar LSC of equivalent collection area and volume, depending on the absorption coefficient of the host material. An additional increase in optical concentration of at least ∼4.5% can be attained by aligning cylinders side by side to take advantage of multiple reflections between neighbouring cylinders; it is shown that this multi-cylindrical LSC reflects less incident light than a planar LSC for any angle of incidence.
TL;DR: In this article, an intense red upconversion is observed from the 5D0 level of Eu3+ ions through energy transfer from Yb3+ to Eu 3+ ion when excited with 980 nm.
Abstract: Oxyfluoroborate glass co-doped with Eu and Yb ions has been prepared and characterized for its optical properties through photoluminescence, absorption and lifetime measurements. An intense red upconversion is observed from the 5D0 level of Eu3+ ions through energy transfer from Yb3+ to Eu3+ ion when excited with 980 nm. The Judd–Ofelt parameters have been evaluated to estimate the local site symmetry around the Eu3+ ions. These parameters have been used to derive radiative properties such as transition probabilities, branching ratios, radiative lifetimes and stimulated emission cross-sections for the 5D0–7FJ transitions. Decay of excitation of the 5D0 level has been measured by monitoring the 5D0→7F2 transition (613 nm) at room temperature. Quantum efficiency for this transition is found to be 73%. We also monitored the effect of temperature on the fluorescence emission of Eu3+.
TL;DR: In this article, temperature sensing schemes based on fluorescence intensity ratio and fluorescence lifetimes have been compared on the basis of experimental and theoretical approaches, taking Pr3+ as an example.
Abstract: Temperature sensing schemes based on fluorescence intensity ratio and fluorescence lifetimes have been compared on the basis of experimental and theoretical approaches, taking Pr3+ as an example. The responses of the two techniques based on their sensitivities has also been discussed.
TL;DR: In this article, continuous-wave and Q-switched diode-pumped laser operation of Er,Yb:YVO4 crystal was reported and the lifetime of Er3+4I13/2 and 4I11/2 levels that define laser performance of the crystal were measured.
Abstract: We report on the spectroscopy and, for the first time to our knowledge, continuous-wave and Q-switched diode-pumped laser operation of Er,Yb:YVO4 crystal. Absorption and emission spectra of the crystal were determined. Lifetimes of Er3+4I13/2 and 4I11/2 levels that define laser performance of the crystal were measured and parameters of energy transfer between Yb3+ and Er3+ ions were estimated. cw output power of 115 mW with slope efficiency of 5.4% was achieved at 1604 nm. In the Q-switched mode an average output power of 81 mW with slope efficiency of 3.5% and pulse duration of 150 ns was obtained. In quasi-cw regime maximal peak power of 610 mW with slope efficiency of 6.7% was demonstrated.