High-resolution Laser Spectroscopy Research Articles

Frequency-comb-linearized, widely tunable lasers for coherent ranging

Tunable lasers, with the ability to continuously vary their emission wavelengths, have found widespread applications across various fields such as biomedical imaging, coherent ranging, optical communications, and spectroscopy. In these applications, a wide chirp range is advantageous for large spectral coverage and high frequency resolution. Besides, the frequency accuracy and precision also depend critically on the chirp linearity of the laser. While extensive efforts have been made on the development of many kinds of frequency-agile, widely tunable, narrow-linewidth lasers, wideband yet precise methods to characterize and linearize laser chirp dynamics are also demanded. Here we present an approach to characterize laser chirp dynamics using an optical frequency comb. The instantaneous laser frequency is tracked over terahertz bandwidth at 1 MHz intervals. Using this approach we calibrate the chirp performance of 12 tunable lasers from Toptica, Santec, New Focus, EXFO, and NKT that are commonly used in fiber optics and integrated photonics. In addition, with acquired knowledge of laser chirp dynamics, we demonstrate a simple frequency-linearization scheme that enables coherent ranging without any optical or electronic linearization unit. Our approach not only presents novel wideband, high-resolution laser spectroscopy, but is also critical for sensing applications with ever-increasing requirements on performance.

High resolution laser spectroscopy of iodine molecule in the 14400–14600 cm−1 range

We have extended our previous work (Torres et al., 2022) by performing absorption laser spectroscopy of I2 in the 14400–14600 cm−1 range, using a narrow linewidth diode laser, whose frequency is actively measured using a calibrated wavelength meter. In this range, we have observed 1204 reference lines, 417 more lines than Salami and Ross (2005). The remaining lines are in good agreement with the works carried out by Gerstenkorn and Luc (1979) and by Salami and Ross (2005). The spectrum predicted by the software Iodine Spec5 reproduced our results very accurately.

An extended laser cavity centered at 780 nm for high-resolution laser spectroscopy applications

Laser diodes (LDs) working in free mode present different types of effects such as shift and broadening of the spectral peak, determined by external factors such as temperature, electric current or mechanical vibrations, which are undesirable when required in applications such as high resolution laser spectroscopy, metrology or laser cooling. To reduce the width of the spectral emission peak of a laser, different configurations or optical setups are used, among which one of the most effective is to extend the optical resonator of the LD and use optical feedback, either with the help of a partially reflective mirror or with a diffraction grating. In this work, we present the design, construction, and characterization of a compact extended-cavity diode laser (ECDL) in Littrow configuration. The ECDL was machined on an aluminum block using computerized numerical control. It operates at a wavelength of 780.24 nm with a maximum output power of 35 mW. The results showed a spectral linewidth of 340 kHz using the self-heterodyne technique and a frequency stability of 0.47 MHz when the cavity was stabilized with an atomic reference.

Nuclear moments and isotope shifts of the actinide isotopes Cf249–253 probed by laser spectroscopy

We report on high-resolution laser spectroscopy studies on Cf249–253 with spectral linewidths in the order of 100 MHz carried out at the RISIKO mass separator at Mainz University. In total three atomic ground-state transitions were investigated and the hyperfine parameters for the odd-A isotopes and isotope shift for all examined isotopes have been determined from the measured spectra. The isotope shift measurements allowed tracking of changes in mean-squared charge radii across the deformed nuclear shell closure at N=152, whereby shape discontinuities were not observed. Experimental hyperfine coupling constants of the atomic ground state were combined with relativistic many-body atomic calculations to extract the nuclear magnetic-dipole moment of Cf249 with improved precision to μI(249Cf)=−0.395(17)μN, whereas μI(251Cf)=−0.571(24)μN and μI(253Cf)=−0.731(35)μN were derived for the first time. Additionally, the spectroscopic quadrupole moments QS(249Cf)=6.27(33)eb and QS(253Cf)=5.53(51)eb were extracted.Received 20 December 2022Accepted 7 February 2023DOI:https://doi.org/10.1103/PhysRevC.107.034313Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFine & hyperfine structurePropertiesA ≥ 220TechniquesAb initio calculationsRadioactive beamsNuclear Physics

High-resolution laser system for the S[formula omitted]-Low Energy Branch

In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S3-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S3. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the 4f126s23H6→4f12(3H)6s6pJ= 5 atomic transition (415 nm) and the tin isotopes were studied by the 5s25p2(3P0)→5s25p6s(3P1) atomic transition (286.4 nm), and are used as a benchmark of the laser setup. Additionally, the tin isotopes were studied by the 5s25p6s(3P1)→5s25p6p(3P2) atomic transition (811.6 nm), for which new isotope-shift data was obtained and the corresponding field-shift F812 and mass-shift M812 factors are presented.

Спектроскопия и фотонное эхо на переходе Er-=SUP=-3+-=/SUP=- с малым неоднородным уширением и телекоммуникационной длиной волны в кристалле YPO-=SUB=-4-=/SUB=-

The results of investigations of Er3+ ions at an optical transition with a telecommunication wavelength (λ~1530 nm) in a YPO4 crystal by using photon echo and high-resolution laser spectroscopy in magnetic fields up to 4 T are presented. The maximum coherence time (T2) was 113 μs in a magnetic field of 4 T when it is oriented along the optical axis c of the crystal. The main sources of decoherence are discussed.

Simulation studies of a 30-keV MR-ToF device for highly sensitive collinear laser spectroscopy

The Multi Ion Reflection Apparatus for Collinear Laser Spectroscopy (MIRACLS) seeks to extend the reach of high-resolution collinear laser spectroscopy (CLS) to more exotic radionuclides. In this novel technique, ion bunches of short-lived radioisotopes are trapped between two electrostatic mirrors of a Multi-Reflection Time-of-Flight (MR-ToF) device at 30-keV kinetic energy. The same ion bunch can be probed by a spectroscopy laser for thousands of times compared to a single probing in the traditional CLS measurement scheme. Thus, the experimental sensitivity is increased by more than one to two orders of magnitude. Extensive simulations are presented, demonstrating the feasibility of high-resolution collinear laser spectroscopy (CLS) in the newly envisioned MR-ToF apparatus operating at ion energies of 30 keV. Once the mechanical design and operational parameters are optimized for the requirements of CLS, the spectral line is neither significantly broadened nor distorted by the combination of CLS and MR-ToF operation. According to the simulations, the storage efficiency and the ion–laser overlap are suitable for laser excitation of the majority of the trapped ions. In summary, >90% injection and storage efficiency, >75% ion–laser overlap and a line width approaching the natural line width of the transition of interest are reached in the simulation.

High-Resolution Laser Spectroscopy of a Functionalized Aromatic Molecule.

We present a high-resolution laser spectroscopic study of the Ã2B2-X̃2A1 and B̃2B1-X̃2A1 transitions of calcium(I) phenoxide, CaOPh (CaOC6H5). The rotationally resolved band systems are analyzed using an effective Hamiltonian model and are accurately modeled as independent perpendicular (b- or c-type) transitions. The structure of calcium monophenoxide is compared to previously observed Ca-containing radicals, and implications for direct laser cooling are discussed. This work demonstrates that functionalization of aromatic molecules with optical cycling centers can preserve many of the properties needed for laser-based control.

Quantifying antisite defect concentrations in yttrium aluminum garnet by high-precision density analysis

Quantifying the nature and density of lattice defects in high-quality crystals is often difficult or impossible with commonly employed material characterization techniques. In many cases, even the density of intentionally doped impurities present in a grown crystal must be inferred indirectly using methods such as mapping spatial variations in crystal properties or, when the defects are optically active, interpreting optical absorption with imprecisely known oscillator strengths. In this work we explore gravimetric techniques to obtain absolute defect densities in crystals, a powerful approach often overlooked in modern materials science. A hydrostatic weighing apparatus based on Archimedes’ principle was constructed, tested, and refined to enable high-precision density measurements of small crystal samples. Application of this system is illustrated by determining the density of Yttrium Aluminum Garnet (YAG) relative to a high-purity silicon crystal density reference, minimizing traditional difficulties in correcting for the variations in surface tension and the water and air density due to small changes in ambient temperature, pressure, and solution composition. This method, using a relatively simple apparatus and small samples, is effective in measuring the intrinsic concentration of Y–Al antisite lattice defects in YAG, agreeing with results from far more elaborate high-resolution optical laser spectroscopy at cryogenic temperatures. Furthermore, we quantitatively analyze the effects of several potential sources for error, including natural variations in isotope distributions, residual surface contamination, and ambient temperature or pressure variations. Subsequently, we find that the density analysis method is a promising technique for characterizing new and modified materials being developed for applications ranging from solid-state lasers and scintillators to quantum information.

Resonant Ionic, Covalent Bond, and Steric Characteristics Present in 1Σu+ States of Li2

The molecular bonding in the excited states of the alkali dimers involves the resonant ionic, covalent bond and steric interactions. We show here the case of the 1Σu+ states of Li2 by ab initio calculation. These interactions as functions of the internuclear distance lead to complex potential energy curves, providing an important application for high resolution laser spectroscopy. The spectroscopic constants for the 4 and 5 1Σu+ states are obtained for the first time.

Resolution Characterizations of JetRIS in Mainz Using 164Dy

Laser spectroscopic studies of elements in the heavy actinide and transactinide region help understand the nuclear ground state properties of these heavy systems. Pioneering experiments at GSI, Darmstadt identified the first atomic transitions in the element nobelium. For the purpose of determining nuclear properties in nobelium isotopes with higher precision, a new apparatus for high-resolution laser spectroscopy in a gas-jet called JetRIS is under development. To determine the spectral resolution and the homogeneity of the gas-jet, the laser-induced fluorescence of 164Dy atoms seeded in the jet was studied. Different hypersonic nozzles were investigated for their performance in spectral resolution and efficiency. Under optimal conditions, a spectral linewidth of about 200–250 MHz full width at half maximum and a Mach number of about 7 was achieved, which was evaluated in context of the density profile of the atoms in the gas-jet.

Commissioning of a high-resolution collinear laser spectroscopy apparatus with a laser ablation ion source

Commissioning of a high-resolution collinear laser spectroscopy apparatus with a laser ablation ion source

A Review of Novel Instrumentation for Matrix Independent Ultratrace Analysis of Radionuclides using Collinear Resonance Ionisation Spectroscopy (CRIS)

The CRIS setup at CERN-ISOLDE is a high resolution laser spectroscopy experiment that is used to characterise exotic radionuclei with very low production rates. Acquisition of hyperfine spectra enable nuclear spins and precise values of nuclear magnetic dipole and electric quadrupole moments to be determined. The high sensitivity of the CRIS technique combined with the high selectivity make it an ideal candidate for quantitation of analytes in complex matrices. This review article reports on novel instrumentation under development at the University of Manchester, utilising the CRIS technique for targeted matrix independent ultra-trace analysis.

Triple-isotope mass balance of mid-latitude, groundwater controlled lake

Lakes constitute an important part of the hydrological cycle on continents. Recent developments in high-resolution laser spectroscopy made feasible triple-isotope, high-precision analyses of water samples (δ2H, δ18O and δ17O). We conducted in-depth, comprehensive assessment of the potential and usefulness of the triple-isotope mass balance approach to quantify water budget of lakes and surface water bodies. A small, groundwater-controlled lake located in the vicinity of Krakow, southern Poland, was selected for this purpose. Approximately 30% higher incoming and outgoing groundwater fluxes derived from 2H-based budget, when compared to 18O- and 17O-based budgets, were obtained when isotopic composition of ambient moisture interacting with the lake was assumed to be in isotopic equilibrium with the local precipitation. Since the ambient moisture interacting with a given lake is in fact a mixture of the vapour released by the evaporating surface water body and the free-atmosphere water vapour, we proposed the procedure to calculate the isotopic composition of this mixture. This approach led to fully consistent triple-isotope mass balance of the studied lake. The underground water fluxes derived separately for the three isotope tracers in use (2H, 18O and 17O) turned out to be identical within the quoted uncertainties, thus supporting internal consistency of the obtained results. The magnitude of the calculated fluxes was in the order of 3200 mm year−1 for the incoming groundwater flux and 3100 mm year−1 for underground losses of lake water through seepage to the local aquifer. The calculated mean turnover time of water in the studied lake is only ca. 16 months, which guarantees a good quality of lake water, a critical parameter in the light of intensive exploitation of this lake as a popular recreational destination during summer.

Characterization of the lowest electronically excited-state ro-vibrational level of 23Na87Rb

Starting from an ultracold sample of ground-state 23Na87Rb molecules, we investigate the lowest ro-vibrational level of the b 3Π state with high resolution laser spectroscopy. This electronic spin-forbidden X 1Σ+ ↔ b 3Π transition features a nearly diagonal Franck–Condon factor and has been proposed useful for probing and manipulating the ultracold molecular gas. We measure the transition strength directly by probing the ac Stark shift induced by near resonance light and determine the total excited-state spontaneous emission rate by observing the loss of molecules. From the extracted branching ratio and the theoretical modeling, we find that the leakage to the continuum of the a 3Σ+ state plays the dominant role in the total transition linewidth. Based on these results, we show that it is feasible to create optical trapping potentials for maximizing the rotational coherence with laser light tuned close to this transition.

High-Resolution Laser Spectroscopy of the Ozone Molecule at the Dissociation Threshold

High-Resolution Laser Spectroscopy of the Ozone Molecule at the Dissociation Threshold

Insights into the Microstructures and Energy Levels of Pr3+-Doped YAlO3 Scintillating Crystals.

Trivalent praseodymium (Pr3+)-doped materials have been extensively used in high-resolution laser spectroscopy, owing to their outstanding conversion efficiencies of plentiful transitions in the visible laser region. However, to clarify the microstructure and energy transfer mechanism of Pr3+-doped host crystals is a challenging topic. In this work, the stable structures of Pr3+-doped yttrium orthoaluminate (YAlO3) have been widely searched based on the CALYPSO method. A novel monoclinic structure with the Pm group symmetry is successfully identified. The Pr3+ impurity can precisely occupy the Y3+ position and get incorporated into the YAlO3 (YAP) host crystal with a Pr3+ concentration of 6.25%. The result of the electronic band structure reveals a 3.62 eV band gap, which suggests a semiconductor character of YAP:Pr. Using our developed well-established parametrization matrix diagonalization (WEPMD) method, we have systematically analyzed the energy level scheme and proposed a set of newly improved parameters. Additionally, the energy transfer mechanism of YAP:Pr is clarified by deciphering the numerical electric dipole and magnetic dipole transitions. The popular red emission at 653 nm is assigned to the transition 3P0 → 3F2, while the transition 3P0 → 3H4 with a large branching ratio is predicted to be a good laser channel. Many promising emission lines for laser actions are also obtained in the visible light region. Our results not only provide important insights into the energy transfer mechanisms of rare-earth ion-doped materials but also pave the way for the implementation of new types of laser devices.

Coherent magneto-optical resonances in hot potassium vapor

In this communication, we present experimental results on the preparation of magneto-optical resonances in potassium. The magneto-optical resonances are registered in Hanle configuration, i.e. monitoring the atomic fluorescence vs the applied magnetic field scanned around zero value. The excitation of the second resonance line with a wavelength of 404.4 nm leads both to direct fluorescence at 404.4 nm and to a cascade decay with fluorescence at 770.1 nm and 764.5 nm (first resonance line transitions). This transfer is evidenced by the registration of a narrow magneto-optical resonance in the fluorescence. It should also be noted that even after multiple cascade transitions, the resonance observed on the infrared lines has a much better signal/noise ratio compared to that on the excited second resonance line. Therefore, the study of these sub-Doppler-width magneto-optical resonances in hot potassium vapor will be useful for the further development of high-resolution magneto-optical laser spectroscopy.

High resolution laser spectroscopy of the ozone molecule at the dissociation threshold

High resolution laser spectroscopy of the ozone molecule at the dissociation threshold

High resolution laser spectroscopy of the ozone molecule at the dissociation threshold

High resolution laser spectroscopy of the ozone molecule at the dissociation threshold