bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical analysis of harmonic generation process in a high-repetition-rate all-solid-state 213nm laser
Authors: Kubota Shigeo , Masuda Hisashi , Wiechmann Werner
Published: February 2023

We reported 0.4W average power all-solid-state 213nm laser, which is a potential candidate for next generation micro-lithography1,2. For this application, the power should be scaled up to more than 5W to be competitive with an excimer laser. To investigate such scalabilty, we analyzed numerically SHG and FHG processes with an intensive tightly focused Gaussian pump beam from Lightwave Electronics model-210 diode-pumped Q-switched Nd:YAG laser of which average power is more than 6W with 35ns pulse width in FWHM at 7 kHz repetition rate. Our apporoch is based on Boyd and Kleinman’s method which is effective to analyze harmonic generation process in a nonlinear crystal with a tightly focused Gaussian pump beam3. However, calculation of pump depletion was only allowed in plane wave approximation4,5. To include the effect of pump depletion into the conversion process, we formulated harmonic power increment at an arbitrary point along the propagation direction (z-direction) of the pump beam in a nonlinear crystal. From energy conservation law, the harmonic increment should be related to pump depletion. Under assumption of homogeneous Gaussian beam depletion, fundamental and harmonic intensity at 800 points along the propagation direction of a fundamental beam in nonlinear crystals were calculated by integrating the fundamental decrement and the harmonic increment on a workstation Sony NWS-5000 in a couple of seconds.
Nonlinear Optical Properties of Au Nanocrystals Embedded in Silicate Thin Films
Authors: Lee Minyung
Published: February 2023

A lot of nanometer-sized metal particles exhibit high optical nonlinearity and fast time response in the surface plasmon absorption region,1 so they have potential application in nonlinear optical devices in the future. Especially, gold nano crystals were most intensively studied and their linear and nonlinear optical properties are relatively well known.2 However, preparation techniques for gold nano particles in inorganic oxide glass are not well established yet and controlling the nanocrystal size has to be elaborated for the systematic study on the nonlinear optical properties of metal nanocrystals.
Third order nonlinear optical properties of metal ion implanted silica at 527nm, 800nm and 1053nm
Authors: Luther-Davies Barry , Samoc A. , M.Samoct  , Magruder Robert H.
Published: February 2023

There is a growing interest in the optical properties of metallic
nanocrystals embedded in dielectric hosts particularly since there
have been reports of these materials having very large third order
optical nonlinearities1. In this paper we present some
results of measurements on materials created by implanting fused
silica with various combinations of titanium, antimony, gold and
oxygen at doses in the range
1016-1017atoms/cm3.
A Comparison of Chlorinated Fluoride Glasses for Obtaining Red Upconversion Fluorescence in Praseodymium for a Three-Color Solid-State 3D Display
Authors: Downing E. A. , Hesselink L. , Macfarlane R. M. , Borrelli N. F. , Bartholomew R. , Newhouse M.
Published: February 2023

We have demonstrated an RGB solid-state 3D display based on two-step, two-frequency (TSTF) upconversion in bulk rare earth doped heavy metal halide glasses.1,2 Figure 1a shows the basic two-step absorption process and figure 1b shows how two scanned pump lasers are made to intersect inside a bulk sample of active material to create three-dimensional images. Green upconversion fluorescence is obtained by pumping trivalent erbium doped glasses with 1.5 um and 850 nm, and blue from pumping Tm3+ doped glasses with 800 nm and 1120 nm. Figure 2 shows the energy level diagrams of these three ions along with the respective resonant pump wavelengths and emission lines.
Multiwavelength Optical Computing Using Optical Wave Mixing in Photorefractive Media
Authors: Wu Weishu , Yeh Pochi
Published: February 2023

Digital optical computing has been proposed for many years. However, much attention has only been focused on the spatial parallelism optics offers. The broad bandwidth of optical waves and optical media has been neglected for quite a long time. In multiwavelength optical computing, the broad bandwidth of optical waves and optics is utilized to increase the throughput of optical computing by using wavelength as an additional dimension.
Dielectric Photorefractive Gratings in KLTN at the Paraelectric Phase
Authors: Agranat Aharon J. , Razvag Meir , Balberg Michal
Published: February 2023

We present experimental evidence indicating that in the paraelectric phase, slightly above the phase transition, photorefractive (PR) gratings are formed by spatial modulation in the low frequency dielectric constant. The PR effect is normally attributed to the formation of spatially modulated space charge, which induces a correlated modulation in the birefringence through the electrooptic effect. In the paraelectric phase the electrooptic effect is quadratic and is given by where Δn is the birefrongence, no is the refractive index, g is the quadratic electrooptic coefficient, and P is the polarization. Therefore, a spatial modulation in the birefringence induced by a modulation of the polarization is given by Assume that P is in the linear region, i. e. P = εE; where ε is the dielectric constant and E is the electric field in the crystal. Then, if Esc(x) is the space charge formed in the PR process, the modulation of the birefringence is given by where Eo is the electric field in the crystal. This is the so called voltage controlled PR effect (1,2). Considering equ. [2] it can be seen that if a modulation in ε is formed, it will induce a modulation in the birefringence given by We have observed that slightly above the phase transition such a dielectric grating was formed in potassium lithium tantalate niobate (KLTN) doped with copper and vanadium. The experiments were conducted in a KLTN sample with a ferrelectric phase transition at Tc =170K. Prior to the experiment the crystal was cooled slowly from 200K to 160K at 0.5K/minute under a field to 1.8kV/cm, and was then warmed slowly to the experiment temperature.
Self Phase Conjugation and Hexagonal Pattern Formation in Photorefractive Potassium Niobate
Authors: Banerjee P.P. , Kukhtarev N.V. , Caulfield H.J. , Dimmock J.O. , Honda T.
Published: February 2023

Self phase conjugation is an interesting new phenomenon discovered in photorefractive (PR) crystals [1]. It gives a simple method for generation of a phase conjugate beam that can be used for image processing [2].
Exact Nonlinear Full-field Anisotropic Analysis of Higher-order Diffraction in Photorefractive Barium Titanate
Authors: Jarem J.M. , Banerjee P.P.
Published: February 2023

Two-beam coupling in photorefractive (PR) materials has been extensively studied in the literature [1]. Theoretical analyses are based on linearized time dependent models [1], empirical predictions and nonlinear steady state albeit approximate theories. The difficulty in providing an analytical nonlinear time dependent theory is due to the inability to exactly decouple the Kukhtarev equations [1], and the fact that in a typical two-beam coupling setup, the PR crystal is finite and has a large linear refractive index mismatch with the surrounding medium if no matching liquid is used, prompting reflections from boundaries.
Near band gap time resolved reflectivity studies of ion implanted and MBE grown GaAs:As
Authors: Janz S. , Wasilewski Z.R. , Akano U.G. , Mitchell I.V.
Published: February 2023

Non-stoichiometric GaAs:As with an excess As concentration of approximately 2% has several unique properties including extremely short carrier lifetimes combined with a high mobility, and a large nonlinear optical response with a picosecond recovery time1,2. This combination of properties is believed to arise from either As related defects or Schottky depletion regions surrounding As precipitate inclusions. GaAs:As with an excess As concentration is usually prepared by low temperature molecular beam epitaxy (MBE) (i.e. LT-GaAs), and more recently by As+ ion implantation3. Time resolved pump-probe transient reflectivity measurements can provide information not only on carrier lifetime, but also on the carrier induced nonlinear refractive index change, △n. In this paper, we report the initial results of a comparative study of the transient optical reflectivity for MBE grown LT-GaAs, ion implanted GaAs:As, and semi-insulating GaAs.
Coherent-transient studies of ZnSe/ZnCdSe multiple-quantum-wells
Authors: Blewett I J , Tookey A , Kar A K , Galbraith I , Horsburgh G , Steele T A , Prior K A , Wherrett B S
Published: February 2023

A sequence of molecular-beam epitaxially-grown multiple-quantum-well samples with varying well-width have been investigated using the two-beam self-diffracted coherent-transient arrangement1. The four samples were grown sequentially to provide a consistent sample set, each with identical substrate, buffer and cap layers. The cadmium concentration and number of quantum-wells were maintained at 20% and fifty respectively and the well-widths were varied from 1nm to 6nm.
Engineering the Second-order Optical Nonlinearity in Semiconductors
Authors: Janz S.
Published: February 2023

Quasi-phase matching techniques have revolutionized the field of nonlinear optical frequency mixing. Nonlinear crystals for conventional second-harmonic (SH) generation require anisotropic linear optical properties to permit the phase matching of the the pump and SH beams. This requirement severely limits useable materials and geometries. The mismatch between pump and SH beams can be compensated by periodically modulating the optical properties of a material, resulting in a quasi-phase matched (QPM) geometry with efficiencies approaching that of conventional phase matched geometries. Although the concept of QPM has been known for more than thirty years, only in the last decade has QPM been widely implemented for a variety of applications1. For example, QPM SH generation with very high efficiencies has been achieved in LiNbO3 and KTP waveguides1, and optical parametric oscillators (OPO) employing QPM structures have been demonstrated2. The advent of QPM has important implications for optical materials science. Virtually any material with a non-zero second-order susceptibility, χ(2) may be useful for nonlinear devices, and so it has become increasingly important to understand and learn how to control the optical nonlinearities in a wide variety of materials.
Generation of terahertz radiation by difference-frequency mixing of femtosecond pulses in InSb and InAs
Authors: Howells S. C. , Schlie L. A.
Published: February 2023

The role of nonlinear optical phenomena in the generation of terahertz radiation via nonlinear mixing of ultrashort infrared laser pulses at semiconductor surfaces is described. Several mechanisms lead to the generation of terahertz radiation from semiconductor surfaces, including depletion-field driven current (current surge),1 bulk difference-frequency mixing (DFM),2 and electric-field-induced optical rectification.3 Previous studies reported that when InSb is illuminated with unfocused above-gap ultrashort optical pulses, the spectrum of the emitted radiation, which is due to the current surge mechanism, shifted to lower frequency as the sample temperature decreased.1,4 This unique feature has led us to study the temperature dependence of difference-frequency mixing from InSb crystals illuminated with focused laser pulses. Increasing the intensity of the 100 fs laser pump beam leads to measurable amounts of terahertz radiation by nonlinear mixing of the spectral components of the pump pulse, as well as a decrease in the current-surge-induced terahertz radiation.2 By rotating an undoped (111) InSb sample about its surface normal, we were able to separate the contribution of the azimuthally-dependent DFM signal from the total terahertz waveform. Contrary to the current surge pulses emitted from (111) InSb, the DFM pulses did not show any frequency shift with temperature. However, there was a pronounced temperature dependence of the DFM pulse amplitude that closely followed that seen from the current surge pulses. Finally, analysis of the angular dependence of terahertz radiation emitted from (100) InAs shows that the dominant nonlinear mixing term is bulk optical rectification.
Functional imaging of neurons with two-photon confocal microscopy using a Saturable-Bragg Reflector-modelocked compact solid state laser
Authors: Knox W.H. , Tsuda S. , Svoboda K. , Denk W.
Published: February 2023

Two-photon excitation laser scanning microscopy (TPLSM) allows high resolution fluorescence imaging with minimal photodamage and photobleaching (for a review see [1]). TPLSM has recently been used to study, for example, information processing in dendritic spines, cell division in developing embryos, and calcium dynamics in auditory hair cells. TPLSM yields intrinsic submicron three-dimensional resolution (Fig. 1) and optical sectioning equivalent to one-photon confocal microscopy simply by spatial confinement of excitation. This eliminates counterproductive absorption outside the focal slice. In highly scattering samples, such as nervous tissue, the red or near-infrared light used for illumination in TPLSM leads to a much improved penetration depth and the absence of a detector pinhole permits ballistic and diffuse photons to contribute to the signal [1]. Because two-photon absorption depends on the square on the instantaneous light intensity, ultrashort pulses are essential for TPLSM to achieve efficient excitation while using low average power. The main impediment to a more widespread use of TPLSM have been the cost, utility, and space requirements for femtosecond modelocked lasers that are based on large-frame argon-ion pump sources. The use of passive modelocking schemes that directly produce pulses of < 100 fs duration is desirable to reduce overall complexity and optimize performance.
Observation of surface oxide properties by the second harmonic magneto-optic Kerr effect in Ni81Fe19 films
Authors: Silva T. J. , Crawford T. M. , Rogers C. T. , Kim Y. K.
Published: February 2023

The surface properties of air-exposed magnetic thin films are attracting increased interest as the magnetic disk drive industry moves toward higher storage densities, requiring ever smaller read sensor dimensions [1,2]. A rapid increase in the magnitude of magnetostriction in NiFe films with thickness below 5-6 nm is attributed to the surface properties of the films, which begin to dominate as the surface layer becomes a larger percentage of the total film volume [1, 2]. NiFe films are of particular interest in this regard, owing to the material’s extensive use in magnetic data storage devices.
Nonlinear Optical Waveguide Spectroscopy of Poly(p-Phenylenevinylene)
Authors: Ueberhofen K. , Garay R.O. , Müllen K. , Bubeck C.
Published: February 2023

Poly(p-phenylenevinylene) (PPV) is a typical representative of conjugated polymers, which have a highly delocalized, one-dimensional conjugated π-electron system. These polymers have found much interest, because most of them can be processed rather easily to thin film waveguides and because of their large third-order nonlinearities [1-3]. Thin films of PPV are prepared by spin-coating of a soluble precursor polymer on fused silica substrates and thermal annealing under vacuum as described recently [4]. We have used thin films of PPV to develop and demonstrate a sensitive characterization method of the intensity dependent refractive index n = n0 + n2I and absorption coefficient α = α0 + α2I. The utility of any material for applications in photonics depends primarily on these quantities.
Magnitude and Sign of the Third Order Optical Nonlinearity in Polydibutylstannane
Authors: Walser Ardie. D. , Priestley Richard , Dorsinville Roger , Zou W. K. , Xu D.Y. , Yang Nan-Loh
Published: February 2023

The field of nonlinear optics plays a major role in the implementation and development of many photonic technologies useful in processing optical information at enhanced speeds. Materials with large optical nonlinearities and fast responses are crucial for the development of these technologies. Recently, silicon based polysilane and polygermane polymers have attracted great interest. As σ electron systems, these polymers are unique in that the σ electron-delocalization along the backbone chromophore renders the polymers transparent through the visible to the infrared in contrast to the π-conjugated polymers which normally absorb strongly in the visible. In this letter we wish to report the first measurements of the third-order nonlinearity of the tin based polymer polydibutylstannane. Due to the large atomic size of tin, the electron polarizability is expected to be high, which allows for the possibility of a large χ3.
Theoretical Considerations on Second-Order Nonlinearities of Organic Molecules
Authors: Wagnière Georges H. , Hutter Jürgen B.
Published: February 2023

It is now widely recognized that the long-wavelength second-order nonlinear optical properties of organic molecules which absorb in the visible or near-UV, may be reasonably well interpreted by semiempirical quantum chemical calculations. Methods such as PPP (taking into account only π electrons), CNDO or INDO (including also σ valence electrons), are generally used in conjunction with the sum-over-states expressions to obtain the tensor elements of β(ω1 + ω2; −ω1, −ω2). Such calculations may predict correct orders of magnitude, show the relative influence of donor and acceptor substituents, and enable one to identify the dominant contributions to particular tensor elements. Although these methods have a common-structure, namely a SCF part followed by some configuration interaction (CI), they also present severe limitations. They are based on a number of particular approximations, and certain intermediate quantities are calibrated on empirical data, which makes in general the results parameter-dependent1-4). This raises the question on how the situation may be improved. With the advent of large-scale vectorized computers, the possibilities of obtaining better molecular wave-functions also by ab initio methods seem promising. How will this affect the computation of nonlinear optical susceptibilities?
Environmental Effects on the Nonlinearities of Organic Molecules
Authors: Marowsky G. , Shen Y.R.
Published: February 2023

We have studied the influence of different environmental conditions on the optical nonlinearities of selected organics in Langmuir-Blodgett type monolayers. Changes in the environmental conditions, such as protonation or de-protonation or addition of nonlinear inactive, however highly polarizing molecules to the species under consideration may influence the nonlinearities in quite different ways. Protonation, as the first example, can enhance or decrease the nonlinearity by producing a new chemical species upon inclusion of a proton in the original structure. An increasing rate of protonation will result in the production of more and more molecules of this new subspecies in the monolayer, an effect that can be conveniently monitored by the concomitant changes in linear optical absorption. Alternatively, we would like to show that changes in the environmental symmetry of a monolayer induce a strong nonlinear polarization which is not present in the isolated organic molecule.
Scaling Law For Molecular Hyperpolarizabilities
Authors: Shelton David P.
Published: February 2023

A scaling law for molecular hyperpolarizabilities is derived and is shown to accurately describe the measured hyperpolarizabilities for an assortment of small atoms and molecules.
Optical Modulation of the Refractive Index in Gallium Arsenide Doping Superlattices
Authors: Pennise C. A. , Bruno J. D. , Tobin M. S. , Simpson T. B.
Published: February 2023

Doping superlattices, also called nipi superlattices, consist of thin alternating n- and p-doped layers of semiconductor material. This periodic doping profile leads to a periodic electric potential perpendicular to the layers. Potential wells for electrons are in the n-type layers, while potential wells for the holes are in the p-type layers. The periodic potential creates an effective band gap in real space, smaller in energy than the direct gap, which is a function of the density of confined carriers, the impurity doping density, and the thickness of the layers. When mobile electrons and holes are generated, they become spatially separated by the electric potential, screen the oppositely charged ionized dopants in their respective wells, and increase the effective band gap. The resulting tunability of electronic states and optical absorption characteristics as a function of carrier density have been investigated theoretically by Döhler and Ruden.1,2
Dc Field Induced Second-Harmonic Generation in PLZT 9/65/35*
Authors: Mukherjee A. , Brueck S. R. J. , Wu A.Y.
Published: February 2023

Centrosymmetry of molecular aggregates having a center of inversion can be broken by applying an external DC electric field and even-order nonlinear optical processes can be studied. Electric field induced second-harmonic generation (EFISHG) has been studied in centrosymmetric polydiacetelene (PDA) to investigate resonant enhancement of χ(3) (-2ω;ω,ω,0) and two photon generation of carriers1 and determine the phase and value of χ(3) (-2ω;ω,ω,0) 2. EFISHG experiments have also been reported on molecules in solution to study the molecular environment3 and influence of carrier substituents4. In this paper, we report the first EFISHG measurements in optically transparent, ferroelectric oxide PLZT (La- doped lead zirconate titanate) ceramic materials.
Exciton Spectra of Compound MoS2 by PAS Method at Room Temperature
Authors: Wang Gui-Fen , Chang J. J. , Ma Gen-Yuan , Zhang Guang-In
Published: February 2023

The Chevrel phase compounds including ternary compounds(1) had been well investigated in view to their high critical temperature superconductivity since seventies. In this concern it is reminiscent to call us to examine the structure of the excitonic spectra of MoS compounds, with important conception in mind in Little and Ginzburg sense.(2) In this paper we report we are able to reproduce the exciton spectra of 2H MoS2 at the absorption edge obtained by B.L. Evans and P. A. Young by conventional method at 77K(3), while ours by more sensitive photoacoustic spectroscopy method but at room temperature. It is easy to obtain the exciton spectra of the superconductive MoS compounds in studies of high Tc superconductive MoS cpmpounds at or near room temperature on this method.
Electrooptical Properties of Nonlinear Dyes in PMMA and Poly-(alpha-methyl-styrene)
Authors: Franke H. , Knabke G. , Frank W.F.X.
Published: February 2023

In optical telecommunications there is a great demand for materials whose optical propagation properties can be influenced by electric fields. For slow switching rates liquid crystals can be used which have extremly high electrooptical coefficients due to mobility of the whole molecule. For higher switching rates electronic properties can be used like POCKELS effect and KERR effect. In order to implement these effects in a polymeric material, this can be doped by a suitable dye in relative small concentrations. The orientation behaviour of pure poly-(alpha-methyl-styrene) (PaMS) has been reported by Muto et al. (1); Singer et al. (2) have studied the electro- optical effect of organic dyes in poly-(methyl-methacrylate) (PMMA) using extremly high electric fields (some 100 V/μm). This paper reports on a study of the electrooptic behaviour of N,N-dihexyl-4-amino-4’-nitro-stilbene, called D 90/87, in PaMS and PMMA.
Optical Nonlinearity and Bistability in Artificial Colloidal Materials
Authors: Li Chun-fei , Wang Li-ming , Cha Zi-zhong , Xu Mai , Fei Hao-sheng
Published: February 2023

There is a growing interest in developing low dimensional nonlinear materials in recent years. Some dielectric, metal and semiconductor microparticles doped into the transparent liquid or the glass to form a kind of zero dimensional material, so-called colloidal media, have very large nonlinearity. There are different nonlinear optical mechanisms for the different size of colloidal particles. It can be divided into three types: First, the particle diameter is comparable with or larger than the wavelength of the incident light about 0.1 μm-100 μm, the nonlinear mechanism is due to laser radiation pressure and thermal effect. For example, the liquid suspension of dielectric spheres [1], in which the third-order nonlinear optical susceptibility X(3), is about 10-4-10-5 (esu) with response time (grating formation time ) of 100-200 ms. Second, the particle diameter is less than the wavelength of the incident light about 100-1000Å, the nonlinear mechanism comes from the resonance of surface plasmon. For example, the metal colloid[2] and the semiconductor-doped glass[3], for them the third-order nonlinear susceptibility X(3) is about 10-8-10-9 (esu) with the response time of 1-10 ns. Third, the particle diameter is comparable with or less than the carrier's de Boroglic wavelength, namely with the quantum size about 50-100Å. For example, the glass doped with semiconductor microcrystallites[4] or the metal colloid with above size[5], for them the third-order nonlinear susceptibility X(3) is about 10-9-10-10 (esu) with response time 10-100 ps.
Comparison Between Picosecond and cw Photorefractive Effect in BaTiO3
Authors: Mullen Ruth Ann , Rytz D. , Boggess Thomas F. , Valley George C. , Bohnert K. , Smirl Arthur L.
Published: February 2023

The magnitude, erasure fluence, and dark erasure time constants for photorefractive index gratings written with single 30 ps pulses of between 1 and 15 mJ cm-2 at 0.532 μm have been reported previously1,2. Here we report, for comparison, cw measurements at 0.515 μm of these characteristics in the same crystal sample.
Nonlinear Measurements of High-Index Glasses
Authors: Hall D. W. , Borrelli N. F. , Dumbaugh W. H. , Newhouse M. A. , Weidman D. L.
Published: February 2023

It has recently been emphasized [1] that transparent glasses with large and fast (< 1ps) nonresonant nonlinearites may be a viable alternative to semiconductor and organic materials for certain photo–optic switching applications, including multi–GHz demultiplexing and highly parallel ‘pipeline’ calculations. We report results of measurements of high–index glasses that exhibit large values of χ3.
Optical Fibers with Negative Group-Velocity Dispersion in the Visible
Authors: Österberg U. , Kuo C. P. , Seaton C. T. , Stegeman G. I. , Hill K. O.
Published: February 2023

In 1978, Hill et al.1 observed that subjecting optical fibers to illumination with green light from an Ar+ ion laser for approximately ten minutes could establish a grating along the fiber core. Reflectivities as high as 90% were achieved, with a bandwidth of approximately 200 MHz. In spite of considerable effort,2,3 no explanation of why these gratings are formed has yet been given. Only recently was it reported4 that these gratings could be formed in any fiber other than the one used in the original experiments by Hill. The use of these fibers as narrow-band reflection filters in various applications has been discussed in the literature.5 However, the work reported here was prompted by an article proposing that optical-fiber gratings would exhibit large negative group-velocity dispersion (GVD) in the vicinity of the wavelength used to create the grating.6 The obvious advantage of this would be the possibility of pulse compression in the visible wavelength region in an optical fiber without having to use an external grating pair. The negative GVD would also make it possible to produce "visible solitons."
Nonlinear Optical Characteristics of Semiconductor-Doped Glass Waveguides
Authors: Finlayson N. , Banyai W. C. , Seaton C. T. , Stegeman G. I. , Cullen T. J. , Ironside C. N.
Published: February 2023

A comprehensive study of the nonlinear optical properties of channel waveguides fabricated in CdSxSe1−x semiconductor-doped glass (SDG) has been conducted. Measurements of the fluence-dependence of refractive index and waveguide transmission have been made as a function of wavelength. Time-resolved measurements have also been carried out. These studies have culminated in the demonstration of picosecond switching in a nonlinear directional coupler.
Free Carrier Induced Third Order Optical Nonlinearities in Semiconductors*
Authors: Yuen S. Y. , Wolff P. A.
Published: February 2023

We have studied a variety of free carrier induced optical nonlinearities in III-V and II-VI semiconductors and compounds by four-wave mixing experiments with Q-switched CO2 lasers. Third order susceptibilities χ(3) in excess of 10-3 esu with picosecond recovery times have been observed. Because of their rapid recovery, these nonlinear processes can operate at high laser intensities without saturating. The dispersion of the susceptibility provides a easy method to determine relaxation times in the 0.1 to 5 ps. range.
Optical Bistability in CDS
Authors: Wegener M. , Witt A. , Klingshirn C. , Daunois A. , Bigot J.-Y. , Eddeqaqi N. Cherkaoui , Grun J.-B. , Gnass D. , Jäger D. , Müller-Vogt G.
Published: February 2023

Optical bistability (OB) has potential applications in optoelectronics [1]. Beside electronic OB, which is usually fast, also photo-thermal OB often has been investigated [1]. Its main disadvantage are switching times in the μs-ms regime. In particular thin (a few μm) CdS single crystal platelets show photothermal OB due to induced absorption at room temperature at 514nm.
Ultrafast Nonlinear Processes in Polysilane
Authors: Yang Lina , Wang Q. Z. , Ho P. P. , Dorsinville R. , Yang N. L. , Zou W. K. , Alfano R. R.
Published: February 2023

Organic polymer materials with large and fast nonlinearities are becoming potential candidates for applications in optical computational devices. The third-order nonlinear susceptibility χ(3) of polysilane whose backbone consists entirely of silicon atoms was measured to be comparable to that of polydiacetylenes for the nonresonance case.1,2 Furthermore, polysilane is transparent in the visible range where polydiacetylenes are absorbing.
Novel Blue-Colored Polydiacetylenes for Nonlinear Optics
Authors: Nakanishi H. , Matsuda H. , Takaragi S. , Okada S. , Kato M.
Published: February 2023

Polydiacetylenes with increased numbers of π-electrons per repeating unit such as those having aromatic rings directly bound to the main chain, or with enlarged polarizability (Fig. 1) must be better candidates for extraordinarily large NLO responses (1). For the materiallization of such structures, it is indispensable to have corresponding diacetylene monomers crystallized in a polymerizable stack, since polydiacetylenes are obtained by topochemical solid-state poly merization (2). In a series of studies on crystal engineering of the polydiacetylenes with directly bound aromatic substituents (Fig. 2) (3), we have found that even donor and acceptor-substituted diphenyldiacetylenes (Fig. 3A) can be crystallized in a polymerizable stack by virtue of intermo1ecular hydrogen-bonds of properly located amide groups (Fig. 2(d)) (4). In this study, the methodolgy has been expanded to the bifunctional diacetylene monomers (Fig. 3B).
Size-Distribution Dependence of Optical Properties of Semiconductor Microparticle Composites*
Authors: Persans P.D. , Tu An , Wu Y-C. , Driscoll T. , Wood H.
Published: February 2023

We shall report the results of structural and optical studies of semiconductor microparticle composites consisting of small (<20nm) CdS
x
Se1−
x
crystallites embedded in a glassy matrix1. Recent studies2–4 have shown this class of materials to have large third-order optical susceptibility with fast response time (< 20ps), therefore it is of great interest for nonlinear optical applications. Before we can assess the fundamental limitations and ultimate promise for these materials it is necessary to increase the base of information relating optical and electronic properties to structural properties such as crystal size, strain, defects, and composition. Surprisingly little work has been published in this area5,6.
Local-field Enhanced Optical Nonlinearities
Authors: Haus J. W. , Kalyaniwalla N.
Published: February 2023

We discuss the enhancement of optical nonlinearities due to local—field effects associated with small particles. This phenomenon is important for the large nonlinear response observed from optical phase conjugation in glass materials impregnated with metal or semiconductor microcrystallites1,2, and from surface-enhanced Raman scattering3 Predictions of optical bistability due to local—field enhancement of nonlinearities have been made in the literature4–7.
Corona-Onset Poling of Nonlinear Molecularly Doped Films
Authors: Knoesen A. , Mortazavi M. A. , Kowel S. T. , Dienes A. , Higgins B. G.
Published: February 2023

A novel poling technique based on corona discharge is used to induce second order optical nonlinear properties in molecularly doped polymer films.
Second-harmonic generation in Langmuir-Blodgett mono- and multilayers of hemicyanine dyes
Authors: Winant P. , Persoons A.
Published: February 2023

Organic molecules with large second-order polarisabilities offer an important potential for applications requiring nonlinear opti cal properties, e.g. signal processing (1). Unfortunately most of these molecules form centrosymmetric crystals unsuitable for second-order optical effects. Recently, this impediment was circumvented by the use of the Langmuir-Blodgett (LB-) technique which allows to construct noncentrosymmetric lattices from organic molecules (2-5). A stringent requirement for the LB-technique to be applicable is the incorporation of long alkyl chains in the molecules, enabling the formation of oriented films.
Optical Parametric Generation in Hydrothermally-grown KTiOPO4
Authors: Vanherzeele Herman , Bierlein J. D. , Zumsteg F. C.
Published: February 2023

KTiOPO4 (KTP) is a widely used material for frequency doubling Nd:YAG lasers and other Nd-doped laser systems emitting around 1.06 μm /1/. Second harmonic generation of a 1.32 μm Nd:YAG laser has also been shown in this material /2/. Recently, second harmonic generation at other wavelengths and sum-frequency mixing of the outputs of a Nd:YAG and a near infrared dye laser has been reported in KTP /3/,/4/. Prior to the latter work, sum frequency mixing in KTP of the signal and idler generated by a parametric LilO3 oscillator has also been described /5/. Here, we report the first observation of single-pass optical parametric generation in hydrothermally-grown KTP. By pumping with the second harmonic of a picosecond Nd:YLF laser system (526 nm), we have obtained high peak power radiation tunable from 600 nm to 4.3 μm.
Saturated Erbium-Doped Fibre Amplifiers
Authors: Laming R.I. , Payne D.N. , Meli F. , Grasso G. , Tarbox E.J.
Published: February 2023

It has not been generally appreciated that the erbium-doped fibre amplifier1 (EDFA) has both a saturation output power which increases with pump power, as well as an ability to operate deep in saturation without signal distortion and interchannel crosstalk2. The latter is a consequence of its slow gain dynamics and is quite different from diode-amplifier behaviour3. Most investigations of the gain-characteristics of EDFAs to date have concentrated on the small input signal regime and attempted to obtain high unsaturated gain for low-pump powers4,5, an attribute which is required for an in-line amplifier. By contrast, in this paper we discuss the application of EDFAs as power (post) amplifiers where the input signal is large and the amplifier saturation behaviour outlined above can be exploited. In the highly-saturated regime we have obtained near-quantum-limited differential pump to signal conversion efficiencies, resulting in 47mW (16.7dBm) of amplified signal for only l00mW of pump power at 978nm. Operating in this mode EDFAs are attractive for application as power amplifiers to ease power budget restrictions in point-to-point digital links, video distribution networks6 and LANs.
Polarization Insensitive Traveling Wave Type Amplifier with Strained MQW Structure
Authors: Magari Katsuaki , Okamoto Minoru , Yasaka Hiroshi , Sato Kenji , Noguchi Yoshio , Mikami Osamu
Published: February 2023

Optical amplifiers are a key device for future optical fiber transmission systems and have been extensively investigated. Traveling wave type semiconductor laser amplifiers (TWAs) are very attractive because high signal gain over 25 dB and high saturation output power over 10 dBm can be easily obtained. However, TWAs have an inherent problem compared with fiber amplifiers; the signal gain of the TE mode is usually larger than that of the TM mode. This is due to the mode confinement factor difference between the TE and TM modes. Various approaches to eliminate this problem have been attempted : introduction of a thick active layer1-2) , a large optical cavity (LOC) structure3), a hybrid configuration using two TWAs4), and so on.
Gain Spectra and Gain Compression of Strained-Layer Multiple Quantum Well Optical Amplifiers
Authors: Wiesenfeld J. M. , Raybon G. , Koren U. , Burrus C. A. , Eisenstein G.
Published: February 2023

In this work we describe an optical amplifier fabricated from a strained-layer multiple quantum well laser diode. The amplifier has a small signal gain in excess of 25 dB and a 3-dB saturation output power (P3
dB
) exceeding 25 mW. In general, amplifiers fabricated from bulk epilayer, buried heterostructure devices have high gain per unit length and small saturation output power. A benchmark for such an amplifier operating at 1.5μm wavelength is a 300 μm long buried heterostructure device, which had small-signal gain of 24.5 dB with P3
dB
of 9 mW.[1] Optical amplifiers fabricated from multiple quantum well laser diodes have significantly higher values of P3
dB
, at the expense of greatly reduced gain. [2,3] The properties of the multiple quantum well optical amplifiers arise, in large part, from the small mode confinement factors, Γ, for these devices, which reduce the gain (proportional to Γ) and increase P3
dB
(proportional to 1/Γ). Thus, a 625 μm long multiple quantum well amplifier with Γ = 0.05 demonstrated small-signal gain of 19 dB and P3
dB
of 42 mW. [2] By reducing Γ to 0.02, a 500 μm long multiple quantum well device with P3
dB
of 115 mW, but with gain of only 8 dB, was reported. [3]
Determination of the gain and saturation characteristics of a semiconductor laser amplifier using a ringlaser configuration
Authors: Tiemeijer L.F. , Thijs P.J.A. , Dongen T. v. , Binsma J.J.M.
Published: February 2023

Determination of the gain of a semiconductor laser amplifier using a tunable laser source or a set of fixed wavelength lasers is a rather time consuming exercise. The reason is that the position of the gain peak and the positions of the local maxima and minima belonging to the residual Fabry-Perot ripple are not known in advance and moreover shift with increasing drive current. Therefore determination of the peak gain at various currents levels, which is desirable to select promising devices worthy of further study or to provide feedback in a fabrication process, involves measuring the gain at various different wavelengths to ensure that the measured value corresponds to a (local) maximum. We present an alternative method of gain determination using the laser amplifier in a ringlaser configuration (fig. 1). This method is very fast and does not require a tunable signal source.
Gain-Shaped Erbium-Doped Fibre Amplifier (EDFA) with Broad Spectral Bandwidth
Authors: Tachibana M. , Laming R.I. , Morkel P.R. , Payne D.N.
Published: February 2023

The Er3+-doped optical fibre amplifier (EDFA) has stimulated much interest for possible application in future communication systems, since its gain band coincides with the third telecommunications window of silica fibre at a wavelength of 1.55μm1,2. Although Stark-splitting of the ground and metastable levels in erbium-doped glass generates a wide spectral bandwidth in an EDFA, its gain spectrum is typically irregular, with a sharp peak around 1.53μm and a broad band with reduced gain to longer wavelengths (see Figure 1, Curve A). Although the amplifier can be operated at wavelengths away from the peak gain3, disadvantages occur due to increased spontaneous-spontaneous beat noise and possible laser action at the peak gain wavelength.
Saturation induced polarized emission in Erbium-Doped-Fiber Lasers
Authors: Locati F.S. , Romagnoli M. , Tamburrini M. , Settembre M.
Published: February 2023

Erbium doped fiber amplifiers are receiving great attention because of their capability of amplifying signals traveling in the third low-attenuation window of telecommunication fibers. It has been shown that the signal gain achieved in such amplifiers may be of the order of 40dB or more(1), with saturation powers as large as 12.5 dBm. One interesting feature of such amplifiers is the insensitivity to the signal polarization state: by rotating the linear polarization of the signal, relative to a linearly polarized pump, gain variations of less than 0.2 dB have been measured(2).
Angled Facet Amplifiers with Low Reflectivity and High Coupling Efficiency
Authors: Wang Z. , Farré J. , Mikkelsen B. , Eskildsen L. , Stubkjaer K.E. , Collar A.J. , Henshall G.D.
Published: February 2023

Low facet reflectivity and high coupling efficiency are key parameters for semiconductor laser amplifiers. The facet reflectivity of amplifiers not only induces the undesired spectral gain ripple but also enhances the intermodulation and crosstalk [1]. High coupling efficiency is important for a high fiber-to-fiber gain and also necessary for a small effective noise figure.
1.47um GRIN-SCH-SQW Laser Diode Pumped Er Doped Fiber Amplifier
Authors: Nakamura K. , Cheng Y. H. , Matsumoto N. , Kasukawa A. , Namiki S. , Okamoto H.
Published: February 2023

An Er doped fiber amplifier (EDFA) is drawing much attention as an optical amplifier. For practical use of this amplifiers, laser diode(LD) pumping is the most important requirement. At present, we have two choices of LD wavelength, 0. 98um and 1.48um[1,2]. In the case of pumping by a 0.98um strained quantum well (QW) LD, high efficiency, large unsaturated gain and low noise characteristics are obtained because of large absorption coefficient and complete three level operation. However since the absorption band is extremely narrow in this wavelength range, we must maintain the pumping wavelength within 4nm, Wavelength control leads not only to cost enhancement of the EFDA but also to a hindrance when the EDFA is operated under the automatic gain control (AGC) or automatic level control (ALC).
20Gb/s Optical Soliton Data Transmission over 70km using Distributed Fiber Raman Amplifiers
Authors: Iwatsuki K. , Suzuki K. , Nishi S. , Saruwatari M.
Published: February 2023

Optical amplification is indispensable for optical soliton transmission to compensate for an inherent transmission fiber-loss[1]. Two kinds of amplification technique has been proposed: distributed amplification[2] and localized amplification[3]. The former offers much longer amplification spacing than the latter, because the former’s gain is distributed almost constantly along the fiber, while the latter’s gain is located locally, which leads to radiating dispersive waves[3]. In this paper, we report 20Gb/s optical soliton data transmission over a total distance of 70km utilizing two Raman amplifiers for fiber-loss compensation. The transmission distance corresponds to 19 soliton periods with our experimental parameters, and this value of 19 soliton periods is larger than any previously reported optical soliton data transmission. Raman gain as high as 10dB with forward and backward pumping by 160mW laser diodes was obtained by using a high Δn dispersion-shifted single-mode fiber as the transmission line. This fiber also has the advantage of transmitting optical solitons with relatively small input peak powers.
Temperature Insensitive Er3+-doped Optical Fiber Amplifiers
Authors: Yamada Makoto , Shimizu Makoto , Okayasu Masanobu , Horiguchi Masaharu
Published: February 2023

An Er3 +-doped fiber amplifier is a very attractive device for single-mode fiber communication systems in the 1.5 μm wavelength band1,2. For the practical applications of optical fiber amplifiers in such systems, the temperature characteristics3-6 of Er3+-doped optical fiber is a key parameter. It has been reported that 1.48 μm pumping is more sensitive to temperature than 0.98 μm pumping.5,6 However, characteristics such as fiber length dependence have not yet been investigated.
A 17 Gb/s Long-Span Fiber Transmission Experiment Using a Low-noise Broadband Receiver with Optical Amplification and Eqaulization
Authors: Hagimoto K. , Miyamoto Y. , Kataoka T. , Kawano K. , Ohhata M.
Published: February 2023

It has been demonstrated that optical amplification techniques using Er3+-doped fiber amplifiers (EDFA) are very effective in enhancing the performance of multi-gigabit/s intensity modulation/direct-detection (IM/DD) repeater systems. [1][2] The bandwidth of the EDFA is broad enough to amplify an optical signal with a few picosecond pulse width, therefore, it can be applied to high-bit-rate systems of 12 Gb/s. [3] On the other hand, for transmission systems of more than 10 Gb/s, chromatic dispersion in single mode fibers causes serious degradation in the transmission characteristics even when an external modulation scheme is used.[2] Recently, compensation of fiber chromatic dispersion has been demonstrated in a coherent detection system [4] and a direct detection system. [5].
Observation of Multi-Wavelength Soliton Collisions in Fiber Amplifier Based Systems
Authors: Andrekson P.A. , Olsson N.A. , Simpson J.R. , Tanbun-Ek T. , Logan R.A. , Becker P.C. , Wecht K.W.
Published: February 2023

Optical communication systems based upon solitons [1] have recently gained considerable interest as a possible scheme for very long-haul repeaterless communication links [2,3]. The implementation of such systems have become feasible due to the availability of efficient diode laser pumped erbium-doped fiber amplifiers (EDFA) [4,5]. Contrary to linear optical pulses, however, closely spaced soliton pulses may interact with each other [6,7]. In addition, solitons of unequal carrier wavelengths e.g. in a wavelength division multiplexing (WDM) system will, due to fiber dispersion, inevitably collide at some point in the system.
Repeaterless Transmission With 62.9 dB Power Budget Using A Highly Efficient Erbium-Doped Fiber Amplifier Module
Authors: Auge J. , Clesca B. , Biotteau B. , Bousselet P. , Dursin A. , Clergeaud C. , Kretzmeyer P. , Lemaire V. , Gautheron O. , Grandpierre G. , Leclerc E. , Gabla P.
Published: February 2023

Laser-diode-pumped erbium-doped fiber amplifiers (EDFA) have recently demonstrated all their potential for very long haul transmissions [1]. In-line EDFA application is clearly identified for long undersea links. However, repeaterless transmissions have many applications, especially over 250 km lengths. Compared to direct detection, heterodyne detection allows to achieve a very high receiver sensitivity, increasing the overall link budget [2], Optical amplifiers highly improve this budget, particularly by compensating for the insertion loss of the external phase modulator in DPSK systems. We report a 565 Mbit/s DPSK transmission experiment at 1.532 μm using an EDFA module at the emission, operating in gain saturation regime. Pumped by laser diodes, this optical post-amplifier delivers an amplified output power exceeding +13 dBm, leading to a repeaterless power budget of 62.9 dB. This gives the potentiality to design over 350 km repeaterless links by use of a pure silica core fiber.