bluuebunny/crossref_metadata_2025 huggingface dataset:
Time Behavior of Non-Radiative Multiphonon Relaxation Processes
Authors: Denner V. , Wagner M.
Published: February 2023

Non-radiative multiphonon transitions are investigated on the basis of a widely used model consisting of an electronic two-level system interacting with a set of accepting and promoting phonon modes. It is assumed that both types of modes have different parity.
Self-Trapping of Excitons in Rare Gas Solids: Measurement of Self-trapping Rates and Influence of Dimensionality
Authors: Roick E. , Gaethke R. , Gürtler P. , Zimmerer G.
Published: February 2023

The wavelike exciton states (free excitons, FE) in rare gas solids (RGS) are not stable. Exciton-phonon interaction induces a lattice deformation at which the excitons are self-trapped (STE). The FE and STE states are separated by a potential barrier. Therefore, in the luminescence spectra of (the heavier) RGS, FE and STE emission coexist1,2. This paper presents new experimental results concerning (i) the self-trapping rate and (ii) the influence of dimensionality on self-trapping.
Luminescent and Photochemical Properties of Molecules Near Rough Metal Surfaces
Authors: Garoff S. , Weitz D. A. , Alvarez M. S.
Published: February 2023

The luminescent properties of molecules near rough surfaces of some metals are radically different than these properties near flat surfaces of the same metal. In both cases, the luminescence is an excellent probe of the electrodynamic interaction among the optical fields, the adsorbate, and the electronic excitations in the metal surface. It is the differences between these electronic excitations in the rough and smooth surfaces which give rise to the new properties found on the rough surfaces. These new excitations also give rise to other unusual inelastic light scattering processes at rough metal surfaces such as surfaced-enhanced Raman scattering (SERS). Thus, our studies of the luminescent processes on rough metal surfaces not only provides information on the electrodynamics at these surfaces but also the origins of their many unusual optical properties.
Application of Delayed Fluorescence of Phytoplankton in Limnology and Oceanography
Authors: Krause H. , Gerhardt V.
Published: February 2023

The phytoplankton synthesizes higher organic substances from anorganic matter and sunlight and normally drives the limnic and maritim ecosystems. The scientists use classical methodes (Draw Water, Cell-counting, Extraction of Chl a, 14C-Method, O2 Productionrate) to monitor the concentration, the population and the primary production, and recently more physical methodes become usual.
Site-Selection Spectroscopy of Pheophorbide-Polypeptide Model Photosynthetic System
Authors: Hála J. , Ambrož M. , Pelant I. , Pančoška P. , Bláha K. , Vacek K.
Published: February 2023

Site-selection spectroscopy has been found as a powerful technique for studying large organic molecules (e.g. porphyrins) as well as more complex systems (e.g. chlorophyll in membranes). In the last decade an extraordinary attention has been dedicated to spectral investigations of photosynthetic systems. In vivo photosynthetic systems are very large and complex objects containing chlorophylls, proteins, membranes,… in some since now not completely known functional and structural organization. Therefore it seems to be very fruitful to start a study on some well defined model photosynthetic systems (e.g. chlorophyll-like molecule bonded to a synthetic sequential polypeptide).
Lasing from a Vibrational Transition of a Molecular Defect
Authors: Gosnell T. R. , Tkach R. W. , Sievers A. J.
Published: February 2023

See MB37 for summary.
Picosecond Luminescence Spectroscopy of Electron-Hole Plasma in GaAs/AlAs Quantum-Well Structure
Authors: Tanaka S. , Kumo M. , Yamamoto A. , Watanabe A. , Kobayashi H. , Mizuta M. , Hukimoto H. , Saito H.
Published: February 2023

See FF19 for summary.
Variations in Emission Properties of ZnSe Crystals Under High Excitation
Authors: Colak S. , Bhargava R.N. , Fitzpatrick B.J. , Sicignano A.
Published: February 2023

There has been a resurgence of studies in wide band gap II-VI semiconductors for applications such as electron beam pumped visible lasers.1,2 For this purpose we have studied the luminescence properties of a variety of ZnSe crystals with various impurities under e-beam excitation densities up to several MW/cm2 for temperatures above 100°K.
Decay of 3d Element Internal Photoluminescence Transition in III-V Semiconductors
Authors: Guillot G. , Benjeddou C. , Leyral P. , Nouailhat A.
Published: February 2023

The decay processes of infrared emissions due to internal transitions after laser excitation have been studied systematically for the first time for several III-V semiconductors (GaAs, InP, GaP) doped with 3d ions (V, Cr, Fe and Co).
Mechanism of Photoluminescence in Hydrogenated and Chlorinated Amorphous Silicon Prepared by Glow Discharge
Authors: Al - Dallal Shawqi
Published: February 2023

Chlorinated and hydrogenated amorphous silicon films have been prepared by glow discharge at various R. F. power. Chlorine content in our samples are measured by electron microprobe analysis. Typical concentration of chlorine is 6%. The hydrogen content is 5 to 10% as calculated by integrating the 640cm−1 wagging band. At low powers (5 watts), the infra-red vibrational spectra show the appearance of a chlorine induced band at 545cm−1 and several hydrogen induced bands at 640cm−1, 740cm−1, 840cm−1, 890cm−1, 2000cm−1 and 2100cm−1.
Photoluminescence Study of Nitrogen Implanted Silicon
Authors: Alt H. Ch. , Tapfer L.
Published: February 2023

Up to now the properties of nitrogen as an impurity in silicon, e.g. the low electrical activity and the strong interaction with dislocations, are hardly understood. Recently Tajima et al. (1) reported a luminescence line at 1.1223 eV which appears only in nitrogen doped samples. Sauer et al. (2) showed that this line is identical to the A transition of the A, B, C system. This system is due to an exciton localized at an isoelectronic defect of axial symmetry around <111> (C3v) the chemical nature of which is still unknown.
Luminescence and Related Optical Properties of Iron Ions in II-VI Compounds
Authors: Roussos G. , Schulz H.-J. , Thiede M.
Published: February 2023

Optical absorption and emission spectra of Fe centers have been studied at low temperatures in chalcogenides of Zn and Cd. For comparison, emission spectra have been recorded with semi-insulating in InP:Fe substrate material.
Electron-Beam Annealing of Green Luminescence of Undoped and In-Doped CdS Crystals:
Authors: Fujieda S. , Takahashi R.
Published: February 2023

It is well known that semi-insulating undoped CdS crystals often show green cathodoluminescence at room temperature. As reported previously, In-doped CdS layer and whisker prepared by vapor reaction show green photo- and cathodoluminescence1) which does not degrade for being left in air for many years. On one hand, In-doped CdS crystals prepared by Piper-Polich method also show the same luminescence2) at room temperature, but the photoluminescence is lost in several months. These empirical facts on the degradation of luminescence of CdS were verified by an experiment of electron-beam annealing as follows.
Concentration Quenching in Nd-Doped Glasses
Authors: Stokowski S. E. , Cook L. , Mueller H. , Weber M. J.
Published: February 2023

We have measured Nd fluorescence lifetimes versus Nd concentration (ρNd) in a large variety of pure, water-free glasses. The Nd self-quenching rate varies as

ρ

Nd

n

where 1<n<3.3, its value depending on glass structure.
Energy Transfer in Ytterbium Doped Inorganic Glasses
Authors: Brundage R. T. , Yen W. M.
Published: February 2023

Energy transfer in glasses has been a topic of interest for some time,1 but due to experimental and theoretical difficulties there has not yet been a satisfactory description of the processes involved. We have carried out time-resolved fluorescence line narrowing (TRFLN) experiments over a range of temperatures in Yb3+ doped inorganic glasses in an attempt to help resolve this problem.
Single- and multi-step energy transfer from Mn2+ to Sm3+ in ZnS:Mn, Sm
Authors: Wu Xu , Xin-yi Zhang , Xu-rong Xu
Published: February 2023

We found that the excitation energy can be transfered from Mn2+ to Sm3+ in ZnS:Mn, Sm.(1) For a given concentration of Mn2+ (CMn), the energy transfer rate (P) varies with the concentration of Sm3+CSm), as shown in Fig.1. But, when CMn increases from lower than 10-4 mol. to 10-3mol., the corresponding dependence of P upon CSm changes from

P
∝

C

Sm

2

to P ∝ CSm. This result can be explained by the different paths of energy transfer : a single-step direct transfer from Mn2+ to Sm3+ for small CMn and a multistep diffusion limited transfer, Mn2+→ Mn2+→⋯⋯→ Sm3 for large CMn. According to the energy transfer theory of dipole-dipole interaction, for diffusion limited transfer(2),

P=4πα

1/4

D

3/4

C

Sm

, where D is the diffusion coefficient, α is a constant. On the other hand, P is proportional to

C

Sm

2

for direct transfer(3).
Up-converted ultraviolet emission in Pr3+:LaF3
Authors: Lezama Arturo , Gomes Anderson S.L. , de Araujo Cid B. , Leite J.R. Rios
Published: February 2023

Ultraviolet (U.V.) pair emission in PrF3 has been reported recently (1). We show here that it can take place even at very low Pr3+ concentration in LaF3 via an up-conversion energy transfer.
Continuous-Time Random Walks and Luminescence Decay in Disordered Systems
Authors: Blumen A. , Zumofen G.
Published: February 2023

See TuC2 for summary.
Photophysical Studies of DAQ on Silica and Aluminum Oxides – – A Molecular Frode of Surface Heterogeneity
Authors: Drake J. M.
Published: February 2023

See TuC4 for summary.
Progress in Understanding of Mechanisms of RE3+ Excited States Nonradiative Relaxation in Crystals
Authors: Gapontsev V.P. , Sirtlanov M.R. , Yen W.M.
Published: February 2023

It was shown earlier [1-3], that the regularities of nonradiative relaxation (NR) of RE3+ excited states in oxide glass hosts are quantitatively described in the frames of model of dipole-dipole energy transfer to those high-frequency molecular oscillators of impurities or host, which overtones have the resonance with electronic transition. However the attempts [2,4] to apply this model to NR description in crystals gave contradictory results. It was pointed the satisfactory agreement of theory and experiment for Y3Al5O12, YAlO3 crystals [2], but for Y2O3 crystal situation was less consolatory [4].
Spectral Studies on Luminescence of Dy3+ in CaSO4 Phosphors
Authors: Mulla M.R. , Pawar S.H.
Published: February 2023

The paper reports comparative study of electroluminescence emission spectra (EES) of CaSO4:Dy with respect to EES of CaS:Dy, CaSO4:Bi, and CaS:Bi. The details regarding phosphor preparation, electroluminescence (EL) cell, electroluminescence set-up etc. have been reported elsewhere(1,2).
Laser Selective Excitation of Fluorine and Hydrogenic Charge Compensated Sites in SrF2:Pr3+
Authors: Syme R.W.G. , Reeves R.J. , Jones G.D.
Published: February 2023

Laser selective excitation methods were used to identify C4v and rhombic symmetry sites in hydrogenated crystals of SrF2:Pr3+. The hydrogenic sites also display local mode vibronic lines which correlate with those measured in the infrared by Edgar et al.1
Two-Photon Excitations of Higher 5d States in Ce3+:CaF2
Authors: Gayen S. K. , Pogatshnik G. J. , Hamilton D. S.
Published: February 2023

The 4f-->5d near-ultraviolet transitions in Ce3+:CaF2 are dipole allowed in one-photon absorption (OPA) and first-order parity-forbidden for two-photon absorption (TPA). A relaxation of the parity selection rule due to odd crystal-field components has previously been observed1 in the TPA from the 4f ground state to the lowest 5d state. In this paper the TPA measurements are extended to include transitions to the higher 5d states.
Site Selective Laser Spectroscopy of Defects in SrCl2:Eu3+
Authors: Wietfeldt John W. , Wright John C.
Published: February 2023

When fluorite crystals, such as CaF2, are doped with trivalent rare earth ions, interstitial fluoride ions are known to provide charge compensation. The fluoride interstitial can exist either in association with a dopant ion, perturbing its electronic state, or in a distant position where the dopant site symmetry becomes cubic. Dimers, as well as higher order clusters, have also been observed.1
Luminescence of Cerium in the System Ba1-xCexMgF4-x
Authors: Banks E. , Xing-ren Liu , Srivastava A. M.
Published: February 2023

Samples of composition Ba1-xCexMgF4+x were prepared by heating in dry nitrogen. At Ce concentrations below 10 mole %, X-rays showed the BaMgF4 structure1. Above that composition a new structure appears. Excitation spectra of samples containing 0.3, 3 and 10 mole % Ce are shown in Figure 1. The excitation peaks shift to longer wavelength as the Ce concentration increases.
Fluorescence Spectroscopy through an Optical Fiber with a Time-Correlated Single-Photon Counting Method
Authors: Kushida Takashi , Watanabe Junji , Kinoshita Shuichi
Published: February 2023

It is possible to determine the spectrum of an optical pulse from the measurement of the photon time-of-flight distribution through a fiber, provided the time resolution of the system, including the original pulse duration and the time broadening of the monochromatic component (time dispersion) within the fiber, is sufficiently short.1)
Differential Lifetime Spectroscopy
Authors: Birch D.J.S. , Imhof R.E. , Dutch A.
Published: February 2023

The single photon correlation technique is now the most popular method of measuring fluorescence lifetimes.1 Lifetime spectrometers traditionally use a single detection channel which necessitates consecutive measurement of the excitation pulse and fluorescence decay in separate experiments.2 if the fluorescence decay is comparable to or less than the duration of the excitation pulse E(t) then the lifetime τ can be determined using reconvolution and a least-squares fit of F(t) to the decay using Equation (1) is widely used but its validity depends passively on the stability of the excitation pulse profile.
Interband transitions and the electroluminescence of rare-earth implanted zinc chalcogenides.
Authors: Bryant F.J. , Hagston W.E. , Krier A.
Published: February 2023

A comparison of the d.c. electroluminescence properties of reverse biased Schottky diodes in ZnS and ZnSe permits a valuable insight into the electronic processes responsible for the production of electroluminescence emission in rare-earth doped samples of these compounds. For unimplanted ZnS, application of an electric field does not result in any inter-conduction band transitions, whereas unimplanted ZnSe does exhibit transitions of this type even at room temperature. The ZnS and ZnSe Schottky diodes were prepared under similar conditions and would be expected to have similar diode properties, but these results indicate that a direct injection of the tunnelling electron into the upper conduction band is possible in ZnSe but not in ZnS.
Time-resolved blue luminescence and temperature-dependent characteristics in efficient forward-bias ZnS diode
Authors: Taguchi Tsunemasa
Published: February 2023

For the study of blue light-emitting diodes(LEDs) using ZnS, from a prac tical point as well as a physical point of view, it is desirable to find out the prerequistie for making reproducible and reliable metal-partially compensated semiinsulating layer–semiconductor (MπS) structure. Since oxygen gives rise to acceptor-like levels which can result in an accumulated layer or a compensated layer being formed at the crystal surface, the application of compensated high-resistive layers due to oxidation might be useful for making an interposed π-layer between the metal electrode and low-resistive n-ZnS to obtain an efficient blue LED. Most recently, we have shown that the chemically oxidised π-layer consists of ZnO and ZnS mixed alloys1), and that the best diode records a room–temperature external quantum efficiency of about 8x10-4 photons/electron and the halfwidth of about 65 nm at a drive voltage of 6 V for 15-20 mA.mm-2 current densities. It is worth noting that these characteristics are superior to those in GaN and SiC2) blue LEDs.
Two-Photon Polarization Spectroscopy in the Spatially Dispersive Region of Exciton Polaritons in CuCl
Authors: Kuwata Makoto , Nagasawa Nobukata
Published: February 2023

Spatial dispersion effect has been one of the most important problems in exciton optics since Pekar pointed out the existence of the anomalous waves in 1957. Because this effect always appears in the highly absorbing region of exciton resonance, it is not easy to study this effect with the ordinary spectroscopy. Recently we have developed the two-photon polarization spectroscopy (TPPS), which is based on the photo-induced optical anisotropy coming from the renormalization of exciton polaritons (EP's) due to the two-photon formation of excitonic molecules (EM's). By this method we can monitor the number of EP's in the spatially dispersive region through the change in the polarization of the probe light with the energy in the transparent region. Here we will demonstrate how the TPPS displays its effectiveness to study the spatial dispersion effect of the EP's in CuCl and show the various features of EP's revealed by this method.
Exciton Transfer and Quenching in Solid Solutions
Authors: Burshtein A. I.
Published: February 2023

Summary not available.
Luminescent and Photochemical Properties of Molecules near Rough Metal Surfaces
Authors: Garoff S. , Weitz D. A. , Alvarez M. S.
Published: February 2023

See MC2 for summary.
Photoluminescent and Electroluminescent Properties of Cd0.95Mn0.03 Electrodes
Authors: Burk A. A. , Ellis Arthur B.
Published: February 2023

See TuF10 for summary.
Characterization of the Luminescent Triplet State of the K2Cr2O7 Crystal at 1.2 K via Electron Paramagnetic Resonance and Optical Spectroscopy
Authors: van der Waals J. H. , van der Poel W. A. J. A.
Published: February 2023

See MB 16 for summary.
Two-Photon Absorption Spectroscopy of Rare Earth Ions
Authors: Bloembergen N.
Published: February 2023

Observations on two-photon transitions in the 4f7 configuration of Gd3+ and Eu2+ reveal the importance of crystal field and spin-orbit interactions in the intermediate 4f6 5d levels.
Evidence for a Double Acceptor Bound Exciton in a II-VI Compound
Authors: Dean P. J. , Kane M. , Skolnick M. , de Maigret F. , Rang Le Si , Nahmani A. , Romestain R. , Magnea N.
Published: February 2023

See FE8 for summary.
Luminescence in pure and Tl+-doped Alkali Halides, excited by Synchrotron Radiation.
Authors: Antonangeli F. , Fermi F. , Grassano U.M. , Piacentini M. , Scacco A. , Zema N.
Published: February 2023

The energy transfer between the site where the photon is absorbed and the recombination center, where the radiative emission takes place, has been investigated in pure and Tl+-doped potassium halides.
Resonant Raman Scattering of the Laser-Active Tl°(1) Defect in KCl*
Authors: Joosen W. , Goovaerts E. , Schoemaker D.
Published: February 2023

The vibrational properties of the laser-active Tl°(1) center in KCl have been studied by means of resonant Raman scattering. This center consists of a substitutional Tl° atom with a negative ion vacancy in a nearest neighbor position and possesses C4v[001] symmetry.1 It was found to be an attractive laser-active center with output in the infrared around 1.5 μm upon optical excitation of the 1.05 μm optical absorption band.2
Luminescence Behavior of Pb2+ in NaCl: Adequacy of a Jahn-Teller Approach
Authors: Jaque F. , Cusso F. , Agulló-López F. , García Solé J. , Martínez J.L. , Manlredi M.
Published: February 2023

It is well known that A band excitation of monovalent ns2 ions incorporated into alkali halide lattices produces two emissïon bands designated as AT and AX [1]. This situation also appears in NaCl:Pb2+ with the special feature that the relative intensity of both emissions depend drastically on the aggregation state and is affected by additional doping with other divalent impurities [2].
Impact Ionization Rate in CdF2 Crystals
Authors: Dallacasa V. , Paracchini C.
Published: February 2023

CdF2 crystals doped with trivalent element and heated in Cd va pour become semiconducting(1). Electronic conduction is observed also in doped samples without any thermal treatment(2). At higher electric fields electroluminescence is also obtained and this effect has been evidenced in CdF2 crystals doped with Ga, Y, Sm, Eu, Gd and Tb.
Singlet Exciton Annihilation in the Picosecond Fluorescence Decay of 1,1'-Diethyl-2,2'-Cyanine Chloride Dye J-Aggregate
Authors: Brumbaugh Donald V. , Muenter Annabel A. , Knox Wayne H. , Wittmershaus Bruce , Mourou Gerard
Published: February 2023

We present a new study which reveals a strong dependence on excitation intensity in the time-resolved fluorescence decay of the J-aggregate of the title dye. Strong intermolecular interaction in the J-aggregate is indicated by the large red shift (1700 cm−1) and band narrowing (1475 to 125 cm−1) in the absorption spectrum compared with unassociated dye molecules in solution. Exciton dynamics in the J-aggregate are interesting because of the lower dimensionality and stronger intermolecular interaction compared to other molecular crystals and because of the photographic spectral sensitization properties of the J-aggregate.
Excimer Migration in Crystals: Analysis of Experiments in Pyrene and Dichloroanthracene
Authors: Dunlap D. H. , Kenkre V. M.
Published: February 2023

Excimers in molecular crystals constitute an intriguing object of study in luminescence investigations. Basic questions have remained un-answered about their formation and about their migration. The latter presents particularly interesting challenges. The necessity of large distortions and considerable activation energies for their motion leads one to expect excimers to be relatively immobile. However, experimental evidence for their motion has been presented several times in the literature. Such evidence has been gathered both indirectly from the supposed mutual annihilation of excimers as in recent experiments on dichloroanthracene,(1) and more directly from their trapping by dopants as in earlier experiments on pyrene(2) The two kinds of systems involved are representative of two different physical situations; stacks are involved in the former and preformed dimers in the latter. We have analyzed the motion observations from a general theoretical framework and found that considerable latitude exists in the interpretation of the reported observations. We examine the applicability of polaron transport concepts to excimer motion and comments on what further experiments are necessary to remove the considerable uncertainties that exist in our present understanding of excimers.
Effects of Energy Trapping on Time-Resolved Degenerate Four-Wave-Mixing
Authors: Morgan G. P. , Chen S. Z. , Yen W. M.
Published: February 2023

Time resolved four-wave-mixing has proven to be a useful tool for studying the spatial transfer of energy in optically active materials. When spatial migration of energy occurs, it is found that the transient grating decays with a lifetime which is less than half the fluorescence lifetime of the excited species. By studying the dependence of the decay rate on the grating periodicity, a diffusion constant for the energy transfer can be obtained.
Nature of Phonons Assisting Spectral Transfer in Ruby
Authors: Monteil A. , Duval E. , Attar A. , Viliani G.
Published: February 2023

The observation of one-phonon assisted non-radiative spectral transfer1 is one of the several not well understood features of ruby. Actually, due to the small energy mismatch between Cr3+ sites (<1 cm−1), the density of phonon states is low and, more important, destructive interference was expected2 because of long wavelength. On such grounds, a two-phonon process should dominate even at low temperature (T<50 K).2
Magnetic Field Effect on Ion-Pair Transfer in Ruby
Authors: Montagna M. , Gonzo L. , Pilla O. , Viliani G. , Duval E. , Monteil A.
Published: February 2023

The portion of pair emission in ruby which is due to energy transfer from single ions has been continously recorded as a function of an external magnetic field (in the range 0 - 100 kg) at various temperatures (2–77 K). 3rd and 4th neighbours pairs have been investigated (N1 and N2 emission lines respectively).
Low Temperature Optical Dephasing of Rare Earth Ions by Tunneling Systems in Glass
Authors: Broer M.M.
Published: February 2023

Optical dephasing of paramagnetic ions and molecules in organic and inorganic amorphous solids at low temperatures (≲100K) is characterized by unusual temperature dependences and enhanced relaxation rates compared to crystalline systems1. For a large variety of impurity-host combinations the dephasing rate has been found to follow a Tm temperature dependence with m approximately 2. Several theories have attempted to explain this behavior by assuming interactions between the optical center, phonons, and atomic tunneling systems. However, the role of the intrinsic disorder in optical dephasing in these systems is not clearly understood.
Thermal Zero-Phonon Line Widths of Impurities in Crystals: Theory and Experiment
Authors: Hsu D. , Skinner J. L.
Published: February 2023

See WE1 for summary.
Phonon Processes in Disordered Systems Probed by Spectral Hole Burning and Refilling of Dyes
Authors: Bogner U. , Roska G. , Schatz P.
Published: February 2023

See WE12 and WEI3 for summaries.
Triplet Exciton Recombination in Amorphous and Crystalline Semiconductors
Authors: Cavenett B. C.
Published: February 2023

The occurrence of the excited triplet state in crystalline materials has long been associated with molecular and related crystals which have been investigated by a variety of techniques for ~20 years (e.g. see articles in Clarke (1)) whereas in semiconducting crystalline materials the excited or exciton state has generally been associated with electron-hole pairs where the orbital character of the holes (J = 3/2) is reflected in the electronic structure. However, in recent years a combination of detailed luminescence spectroscopy combined with optically detected magnetic resonance (ODMR) studies have demonstrated that in the case of defect complexes which place the host lattice into canpression, the orbital angular momentum of a bound hole is quenched; bound exciton formation is then between two S = 1/2 particles. The resulting singlet and triplet spectra observed in many materials, but particularly Gap, show that donor and acceptors aggregate to give a wide variety of isoelectronic or isovalent centres and recombination via these centres is the dominant radiative process. (2)
Observation of Chaos in a Frequency Modulated CO2 Laser
Authors: Dangoisse Didier , Glorieux Pierre , Midavaine Thierry
Published: February 2023

The output power of a laser containing an elasto-optic modulator exhibits period doubling bifurcations culminating in chaos and periodic windows. Its bifurcation diagram also demonstrates generalized multistability and depends on the rate of change of the control parameter. These show excellent agreement with computer simulations.
Bistability in Intracavity Nearly-Degenerate Four-Wave Mixing
Authors: Nakajima Hisao , Frey Robert
Published: February 2023

Many important effects such as optical bistability or periodic and chaotic self-pulsations have their origin in the interaction of two counterpropagating optical beams of the same frequency in a nonlinear medium. The investigation of the actual behavior of the standing waves set up inside a nonlinear Fabry-Perot etalon by an external pump beam is generally performed by observation of the transmitted beam. As predicted theoritically(1), intracavity phase conjugation is another way to test this interaction between the two counterpropagating pump waves inside the nonlinear cavity.
Instabilities and Higher-Order States of CW Ring Dye Lasers*
Authors: Stroud C. R. , Koch Karl , Chakmakjian Steven
Published: February 2023

The observations of Hillman et al. are extended to study the effects of cavity output coupling, dispersion, and pump power on the multimode instabilities that occur far above threshold.
Dye Laser Model with Multiplicative Colored Noise
Authors: Jung P. , Risken H.
Published: February 2023

A single mode laser model with fluctuating pump parameter is in use to describe the statistical properties of the light intensity of a Dye laser [1-4]. The normalized Langevin equation with multiplicative colored noise read where ϵ represents exponential correlated noise with the noise strength D and the relaxation time γ-4[5-7]. The equivalent two variable Fokker-Planck equation has the form [5,8,9]
Semi-classical Limit of Chaos and Quantum Noise in Second Harmonic Generation
Authors: Dörfle M. , Graham R.
Published: February 2023

Second harmonic generation and subharmonic generation in a cavity are described by the usual master equation (1) for the statistical operator of the system of two modes (fundamental and second harmonic). The master equation is equivalent to a partial differential equation for the Wigner function which is a generalized Fokker-Planck equation involving partial derivatives of the first, second and third order (2). In the semi-classical limit the third order derivatives are negligible and the Wigner distribution satisfies the Fokker-Planck equation equivalent to the Langevin equation with the formally classical Gaussian white noise ξ1, ξ2 with the only non-vanishing correlation coefficients β1, β2 are the mode amplitudes (normalized to photon numbers), g is the coupling constant, Δ1, 2 the frequency mismatch, x is the damping rate, Fp the amplitude of the pump field.
Type-III Intermittency in a Simple Model of a Laser with Intracavity Absorber.
Authors: Velarde M.G. , Antoranz J.C.
Published: February 2023

Transition from a limit cycle to chaos via type-III intermittency /1/ has been studied in a simple model of a laser with intracavity saturable absorber /2-4/. The limit cycle branches from a finite amplitude cw steady state. Within the chaotic region we have also found several time periodic windows. There is also another transition to chaos via intermittency from a softly excited limit cycle bifurcating from the no lasing state. Poincaré and return maps together with power spectra have been used to characterize the properties of the periodic and chaotic states.
Chaotic Pulsation of Semiconductor Lasers with a Proton-Bombarded Segment
Authors: Kuznetsov M. , Tsang D. Z. , Walpole J. N. , Liau Z. L. , Ippen E. P.
Published: February 2023

Recently, a number of theoretical and experimental observations have been made demonstrating chaotic dynamical behavior in nonlinear optical systems. In particular, light output from semiconductor lasers can become chaotic or irregular under external modulation1-2 or when the laser is coupled to an external cavity3-6. In this paper, we report observation of chaotic pulsation in semiconductor lasers with a proton-bombarded segment. Stable and chaotic pulsation regimes of operation were observed both for the isolated laser and the laser coupled to an external cavity.
Overview of the Theory of Optical Bistability
Authors: Carmichael H. J.
Published: February 2023

The theory of optical bistability can be developed at various levels of sophistication.(1) In this overview I have chosen an approach which I hope will make the simplicity and generality of the phenomenon clear, and be suited to the emphasis of this meeting. I will describe a deterministic, semiclassical theory of optical bistability, based on coupled Maxwell-Bloch equations. Statistical and quantum statistical theories will not be included. I also limit my attention to questions concerning steady states and their stability, leaving the theory of higher bifurcations to other speakers.
Modulational Instabilities in Passive Optical Resonators
Authors: Moloney J.V.
Published: February 2023

Spatio-temporal effects play an important role in the transition to turbulence in diverse physical systems. In both Rayleigh-Benard convection and Taylor Couette flow, for example, the onset of a new temporal motion (e.g. periodic to quasiperiodic) is accompanied by the sudden appearance of small periodic spatial scales in the fluid 1. We shall show that a similar situation applies in nonlinear optics. In particular, it has recently been shown that the plane wave Ikeda map describing the dynamics of a ring cavity is more unstable to fluctuations with a transverse spatial structure than to plane wave perturbations 2. As a consequence this simple map cannot provide a correct description of the instabilities. Instead we predict new and diverse routes to optical turbulence under different physical conditions.
Instabilities and chaotic emission of far-infrared NH3 lasers
Authors: Klische W. , Weiss C. O.
Published: February 2023

We have investigated the dynamic behaviour of NH3-lasers. These have narrow homogeneous linewidths, high gain and the inhomogeneous broadening can be controlled (suppressed), and are therefore likely to display instabilities, even under homogeneous broadening conditions. The collisional and radiative processes leading to laser gain are well understood, all laser parameters are controllable.
Sideband Instabilities in a Homogeneously Broadened Distributed Feedback CH3F Laser
Authors: Lawandy N. M. , Rabinovich W. S.
Published: February 2023

The distributed feedback (DFB) laser was first studied by Kogelnick and Shank1. They considered the behavior of a system with a flat gain and a periodic spatial modulation of both the gain and index of refraction. Sargent et al. studied the case of finite gain bandwidth with a simple line shape2. These systems all exhibited a unique solution for the distributed feedback mode equations. Casperson showed that hole burning in a Doppler lineshape may lead to side-bands in a conventional laser3. We have considered the case of an acoustic wave distributed feedback gas laser (AWDFBGL) in which an acoustic wave provides both periodic index and gain modulation. Our model system is homogeneously broadened CH3F gas with a complicated gain lineshape due to molecular structure and A. C. Stark effects induced by the intense CO2 TEA laser pumping4. This system is attractive as it allows for large gains (> 10m−1) with narrow line widths and long Bragg spacings.
Excitation Dependent Dephasing and the Stability of the Lorenz Model for a Homogeneously Broadened Unidirectional Ring Laser
Authors: Lawandy N. M. , Fahmy Ali , Lee Kayee
Published: February 2023

The derivation of the mean field limit equations for a unidirectional homogeneously broadened ring laser is based on the density matrix derivation of the induced atomic polarization. This approach utilizes phenomenological longitudinal and transverse relaxation rates γ11 and γ⊥, which are assumed to be independent of the values of the density matrix elements. This restriction may in some cases be unrealistic, especially in gaseous systems. It is well known that the collision cross-sections for atomic species such as Na are state dependent. These alterations are in fact responsible for effects such as laser induced diffusion[1],[2].
Semiclassical Analysis of the Detuned Ring Laser with a Saturable Absorber
Authors: Chyba D. E. , Abraham N. B. , Albano A. M.
Published: February 2023

We present new results which provide a more complete theoretical understanding of the instabilities, bifurcations, and transition to chaos in the output of the ring laser with a saturable absorber. In particular, we describe this system with no restrictions on the cavity tuning or resonant frequencies of the amplifying and absorbing atoms (the "fully detuned" case).
Non-Feigenbaum Route to Chaos of a Nonlinear Ring Cavity with Infinite Temporal Dimension
Authors: Le Berre M. , Ressayre E. , Tallet A. , Gibbs H. M.
Published: February 2023

The equations of motion for a ring cavity containing a cell of two-level atoms are where E0 and ε(t) are the cw input and intracavity electric field amplitudes at the input mirror. The phase difference {ϕ(t) - ϕ(0)} gives a measure of the amount of energy absorbed by the atoms and χϕ(t) is proportional to the instantaneous complex nonlinear refractive index. Other parameters in Eqs. (1) and (2) are the reflectivity factor R = 1 - T, γ-1 the inversion relaxation time for an atom, and τR the round-trip time.
Mode Analysis of a Hybrid Bistable Device
Authors: Vallee Réal , Delisle Claude
Published: February 2023

The exact scenario leading to chaos in infinite dimensional systems systems described by differential-difference equations (DDE) has attracted a lot of attention recently. The electro-optic bistable device which is described by that sort of equation was shown by Gibbs & al.1 (after a prediction by Ikeda & al.2) to reach chaos after a truncated perioddoubling sequence resembling the case quantitatively studied by Feigenbaum. However in the chaotic region, the electro-optic system shows windows of "frequency-locked" oscillations and other features that cannot be interpreted in the frame of a one-dimensional analysis.
Instabilities Of Actively Mode-Locked Homogeneously Broadened Lasers Induced By Self-Phase Modulation
Authors: Piche Michel
Published: February 2023

Phase-locking of a multimode laser results in the emission of a train of short pulses of constant shape1. This can be achieved by modulating the cavity losses at a frequency matched to the transit time in the resonator. The short pulse circulating in a pulsed laser can be compressed2 by inserting a Kerr medium in the laser cavity, provided self-phase modulation in the Kerr medium is properly adjusted to the dispersion of the gain medium. Self-phase modulation is also known1 to degrade the short pulse shape in several mode-locked solid state lasers.
GaInAsP/InP Avalanche Photodiodes*
Authors: Hurwitz C. E. , Hsieh J. J.
Published: February 2023

An avalanche photodiode with high quantum efficiency in the 1.0-1.3 μm wavelength range will be an important component of IOCs to be used in this low loss, low dispersion regime of optical fiber transmission. In this paper we report for the first time the successful fabrication of avalanche photodiodes in the quaternary alloy GaInAsP, grown epitaxially on InP substrates. Uniform gains of 12, a rise time of 200 psec and low-bias quantum efficiencies in excess of 40% have been measured at 1.15 μm.
Semiconductor Waveguide Switches*
Authors: Leonberger F. J.
Published: February 2023

Waveguide switches are required for the development of many monolithic
integrated optical circuits (IOCs) to provide modulation and selective
routing of optical signals. For many applications, low crosstalk
(e.g., 20 dB) between the signals is necessary. It is especially
desirable to develop such switches in GaAs-based compounds because of
the potential to fabricate integrated laser sources. This paper
reviews progress in the development of these semiconductor waveguide
switches. Other semiconductor waveguide modulators (e.g.,
electroabsorption) will also be discussed briefly.
Electrooptic Analog-to-Digital Conversion using Channel Waveguide Modulators
Authors: Taylor H. F. , Taylor M. J. , Bauer P. W.
Published: February 2023

Analog-to-digital (A/D) converters are widely used to translate sensor measurements into the digital language of computing, information processing, and control systems. Some of these systems, such as signal processors for wideband radars, are limited in performance by the speed of present A/D converters. A new type of A/D converter based on electrooptic modulation of light in channel waveguides has been proposed1. This paper discusses the design of such a device and presents some experimental results on electrooptic A/D conversion.
GaAs - GaAℓAs Injection Lasers on Semi-Insulating Substrates Using Laterally Diffused Junctions
Authors: Lee C. P. , Margalit S. , Yariv A.
Published: February 2023

We have recently reported on the fabrication, for the first time, of GaAs-GaAℓAs injection lasers on semi-insulating substrates [1]. Such lasers will be necessary for integration into complex monolithic optical circuits where individual active components need be electrically insulated from each other [2]. In the reported laser the gain region was limited transversely to a narrow stripe by the current crowding effect. It oscillated in a number of transverse modes making for unstable spatial and spectral characteristics. These instabilities were largely eliminated by resorting to lateral injection of current from a zinc diffused P+ region. The resulting lasers, in addition to their stability, have very low threshold currents.
Masked Molecular Beam Epitaxy
Authors: Cho A. Y. , Tsang W. T.
Published: February 2023

The goal of integrated optics is to integrate monolithically various optical components such as light sources, couplers, waveguides, switches, filters, modulators, and detectors onto a single wafer. To achieve this goal, a technology is required for the preparation of high quality semiconducting layers of different electrical and optical properties, and at the same time, these layers have to be shaped into appropriate configurations to perform their specific functions. Molecular beam epitaxy(1) has the potential to fulfill these requirements. The favorable feature of MBE is the ability to grow epitaxial layers over a large area with precise layer thickness and composition profiles. Furthermore, it permits the use of controlled masking during the growth of the epitaxial layer so that various structures may be formed on the wafer monolithically.
Room-Temperature Ga(1-x)AlxAs-GaAs Double Heterostructure Lasers Grown by Chemical Vapor Deposition
Authors: Dupuis R. D. , Dapkus P. D.
Published: February 2023

Since the first development of GaAlAs-GaAs heterostructure lasers (1-3) most of these devices have been grown by liquid-phase epitaxy (LPE) (4). In the past few yeras, another technique, that of molecular-beam epitaxy (MBE), has been extensively studied (5) and used to grow structures for room-temperature double­heterostructure (DH) GaAlAs-GaAs lasers (6). Both of these techniques have inherent disadvantages and limitations for the large-scale, cost-effective production of such devices.
Application of Fiber Faraday Rotators in Raman Lasers
Authors: Stolen R. H. , Turner E. H.
Published: February 2023

Fiber Raman lasers1 require various intracavity elements such as wavelength selectors, isolators and output couplers. These introduce losses, not only from absorption and reflection, but also from wavefront distortions which can severely reduce coupling into single-mode fibers. We describe here a fiber Faraday rotator which circumvents these loss problems by using the same birefringent single-mode fiber2 as the oscillator. The birefringence is essential for maintaining linear polarization and is responsible for the wavelength selectivity of the Faraday rotator. The present device is a 90° rotator which increases the efficiency of pump coupling and feedback and permits continuous variation of the output coupling. Similar devices could be used for tuning, isolators or unidirectional elements.
Room Temperature CW Operation of 1.5-1.6μm Wavelength Range GaInAsP/InP Lasers
Authors: Arai S. , Kishino K. , Itaya Y. , Asada M. , Tanbun-ek T. , Suematsu Y.
Published: February 2023

Recently 1.5-1.6μm wavelength range lasers have been staged as very attractive sources for ultra low-loss optical fiber communications. (1) These wavelength range can be covered with GaInAsP/InP DH lasers.(2)-(5) Low threshold 1.45-1.65μm (100) GaInAsP/InP laser was obtained(6) by use of anti-meltback layer to prevent the meltback problem of GaInAsP active layer.(7) Room temperature CW lasing operations of 1.5μm range GaInAsP/InP laser were realized respectively at 1.51μm(6) and 1.56μm(8) in wafer structure with anti-meltback layer and 1.55μm(9) by use of low temperature crystal growth technique. From above mentioned point of view, it is considered to be very interesting to develop efficient CW GaInAsP/InP lasers covering whole long wavelength range of 1.5 to 1.65μm.
Bragg-Effect Polarizer/Analyzers and Lens-Less Waveguide Beam Expanders*
Authors: Stoll H. M. , Soady W. E.
Published: February 2023

When properly configured, the 90° Bragg waveguide deflector may be used to serve a number of integrated optical functions[1]. In this paper we discuss its use as a polarizer/analyzer and as a lens-less waveguide beam expander. Applications of the Bragg-effect polarizer/analyzer include polarization duplexing for optical communications systems and output analyzation for guided wave intensity modulators. The lens-less Bragg-effect beam expander may be used as source collimator in real-time acousto-optic signal processing circuits[2].
A Thin-Film Spectograph for Guided Waves
Authors: Tien P. K. , Capik R. J.
Published: February 2023

We discuss in this paper diffraction of guided waves by a concentric-arc grating in a slab waveguide and apply this diffraction phenomenon to form a novel spectrograph for the guided waves. We find it also interesting that optics in this spectrograph resemble that of the well-known "Rowland Circle"1 associated with the Paschen mounting of the ordinary spectrograph.
A Digitally Driven Integrated Amplitude Modulator
Authors: Papuchon M. , Puech C. , Schnapper A.
Published: February 2023

Integrated optical amplitude modulators or switches reported to date are operated with an analog electrical signal(1). However it has been recognized that for some applications, such as data preprocessing aboard spacecrafts, it would be interesting to be able to drive directly this kind of optical element with a digital word. We shall report here the principles of operation of a digitally driven amplitude modulator and describe the experimental results we have obtained.
Be Implanted (GaAl)As Stripe Geometry Lasers
Authors: Bar-Chaim N. , Margalit S. , Ury I. , Wilt D. , Yust M. , Yariv A.
Published: February 2023

Ion implantation has gained much attention recently as a fabrication technique for GaAs optoelectronic devices. Hunsperger et al1 produced p-type layers in GaAs by implanting Be at an energy of 40 keV. More recent investigations have reported on the electrical properties of GaAs implanted with Be at energies up to 400 keV.2-4 Planar p-n junctions were fabricated with low leakage currents and abrupt breakdown characteristics.5 No information has yet been reported on Be implantation in GaAlAs.
New Aspects of Titanium Diffusion in Lithium Niobate
Authors: Esdaile R.J. , McLachlan A.D. , De La Rue R.M.
Published: February 2023

Many different acousto-optic and electro-optic waveguide devices using titanium-diffused lithium niobate have been described (1,2,3). There have also been several studies of the actual titanium diffusion process and it has become evident that this is a complex process involving a number of distinct intermediate stages. Because of this complexity, precise characterisation of the waveguide profile has proved difficult, particularly in stripe waveguide devices.
Ion Exchange for Optical Waveguides in LiNbO3 and LiTaO3
Authors: Jackel J. L.
Published: February 2023

This report describes the use of silver-lithium and thallium-lithium ion exchange to produce waveguides in lithium niobate and lithium tantalate. Fabrication of optical waveguides is a necessary prerequisite for making integrated optics devices. At present the most usual technique for making such guides is the diffusion, at high temperatures, of titanium into LiNbO3. While this method has proved successful for numerous applications, it has certain shortcomings. First, for some applications, wavelength filters, for example, an index increase (Δn) higher than that available with titanium diffusion is desirable Second, LiTaO3, rather than LiNbO3, may be he preferred substrate because of its much lower susceptibility to optical damage. Since LiTaO3 has a Curie temperature considerably lower than any practical diffusion temperature and therefore requires repoling after diffusion in order to recover its electro-optic properties, diffusion of titanium, or of other metals, is not an appropriate technique for this material. Although it has been shown that an electric field can be used to drive copper ions into LiTaO3 at temperatures low enough that repoling is unnecessary,1 the presence of copper produces a colored crystal with strong absorption in both the visible and near IR.2