Spectroscopic characterization of semiconductor doped colour filter glasses

Fresh and photodarkened Schott RG645 and RG665 colour filter glasses are investigated in detail by absorption and emission spectroscopy. The CdS_xSe_1-x volume fraction is deduced from absorption measurements applying Maxwell Garnett theory. The cluster size is determined by Rayleigh scattering measurements. Groundstate and excited-state absorption cross-sections as well as the number density of interacting states are determined from nonlinear transmission measurements using a femtosecond dye laser. The temporal absorption recovery is studied. The fluorescence quantum distributions, quantum yields, and degrees of polarization are determined. A relaxation scheme in an energy band diagram is presented and dynamic parameters are deduced.     

Enhancement of third-order nonlinearity in Ag-nanoparticles-contained chalcohalide glasses

Ag-nanoparticles were embedded in 56GeS₂?C24Ga₂S₃?C20KBr chalcohalide glass with average size varying from 100 to 300 nm. A large femtosecond optical Kerr effect indicated an enhancement of third-order optical nonlinearity due to Ag-nanoparticles observed by AFM images. Among these Ag-nanoparticles-embedded chalcohalide glass samples, the sample (c) with the second largest implanting dose 1 × 10¹⁷ ions/cm² showed the largest value of ??⁽³⁾ 5.34 × 10^?13 esu, which was ten times larger than that of the substrate. The nonlinear relation between the implanted dose and third-order optical nonlinearity is strongly related to the intrinsic local field and Ag-nanoparticles interaction in the glasses.     

Linearity and nonlinearity of quantum-dot semiconductor optical amplifiers

Linearity and nonlinearity of quantum-dot semiconductor optical amplifiers (QD-SOAs) are analyzed in this paper using numerical and analytical solutions. The basic formulas are derived from rate equations of multiple-states QD-SOAs. The solutions reveal that linearity and nonlinearity of QD-SOAs, which is quantificationally characterized by the maximal linear output power and the nonlinear factor, are strongly dependent on injected current, modal gain and spontaneous radiative lifetime. Additionally, the solutions also provide some useful suggestions in designing and using of QD-SOAs, either be used in linear or nonlinear operational region.     

Research progress of third-order optical nonlinearity of chalcogenide glasses

Chalcogenide glasses(ChGs) are a promising candidate for applications in nonlinear photonic devices. In this paper,we review the research progress of the third-order optical nonlinearity(TONL) of ChGs from the following three aspects:chemical composition, excitation condition, and post processing. The deficiencies in previous studies and further research of the TONL property of ChGs are also discussed.     

二维胶体玻璃中玻色峰与结构无序度的关联

本文从实验上研究了胶体玻璃在相同面密度下随着体系结构无序程度的增加, 振动态密度和玻色峰的变化规律. 通过调制两种不同粒径的温敏性水凝胶的数量比来改变体系的无序程度. 通过分析无序体系的声子模式得到体系的振动特性. 研究发现, 随着无序度的增加, 态密度在低频区域增强、玻色峰增高、玻色峰的峰值向低频区域移动. 不同无序程度的样品引起玻色峰的低频声子模式都表现出准局域的特点, 且低频准局域声子模式与样品中无序结构存在关联.     

Second-order optical nonlinearity in Sb2S3 microcrystal doped glasses by electron beam irradiation

With Maker fringe measurements, the prominent second harmonic generation was observed in the sol-gel-derived Sb₂S₃ doped silica glasses irradiated by electron beam, which was related to the space-charge electrostatic field that makes the glasses poled and broken the centrosymmetry of the glasses. By sides, the interface of nanoparticles contributed to the second harmonic intensity as well. The second harmonic intensity increased with the increasing of the irradiating current, accelerating voltage and the concentration of the dopant due to the enhanced built-in electrostatic field. The poled region was located in the surface of the sample about several microns by the TSDC measurements. The second harmonic intensity is almost 10 times larger than that of the base glass due to the existence of microcrystal.     

Spectroscopic studies of tantalum doped borate glasses

Glasses with formula 30Li₂O 60B₂O₃xTa₂O₅ (10−x) Bi₂O₃ for x=0, 2, 4, 6 and 8 were prepared via normal melt quenching technique and characterized by refractive index and MDSC. Refractive index (μ) and glass transition temperature (T_g) are found to increase with increase in dopant concentration. Impedance spectra of the samples were recorded in the frequency range 100 Hz–5 MHz in the temperature range 175–275 °C. The plots are typical of those recorded for disordered systems. Conductivities and relaxation times are found to follow Arrhenius type of relation and activation energies are calculated. Optical absorption spectra were recorded in the wavelength range 200–900 nm range from which cutoff wavelength (λ_c) and optical band gap energy (E_g) are evaluated. λ_c is found to decrease while E_g to increase with increase in composition. FTIR spectra of the samples were recorded in the frequency range 400–1500 cm⁻¹ which exhibit characteristic bands corresponding to BO₃, BO₄ stretching vibrations and BO bending vibration. Tightening of the structure is indicated by increase in the vibration of BO₃ at the cost of BO₄ for 8 mol% of Ta₂O₅. This is in support of the highest value of T_g for this sample among the series. Raman spectra of the samples were recorded in the frequency range 200–1200 cm⁻¹. With successive addition of Ta₂O₅, increase in the vibration of Ta–O groups TaO₆ groups to be responsible for observed increase in μ and T_g. An attempt is made to prepare tantalum doped borate glasses and study them by spectroscopic techniques.     

Intersubband optical nonlinearity and bistable behavior of semiconductor superlattices

The optical nonlinearity and bistability (OB) induced by intersubband transitions (ISBTs) in semiconductor superlattices are studied by means of the Kronig–Penney model and the density-matrix method. The OB state equation in a Fabry–Perot configuration is derived. It is shown that the ISBT-induced OB can be realized over a wide frequency range, and its bistable domain and hysteresis loop are much larger than those of a two-level system. Numerical illustration of the OB behavior in a GaAs/Al_xGa_1−xAs superlattice is also given.     

Optical properties of samarium doped zinc-phosphate glasses

Samarium doped zinc-phosphate glasses having composition Sm₂O_{3 (x)}ZnO_(60−x) P₂O_{5 (40)} (where x=0.1-0.5 mol%) were prepared by melt quenching method. The density of these glasses was measured by Archimedes method; the corresponding molar volumes have also been calculated. The values of density range from 3.34 to 3.87 gm/cm³ and those of molar volume range from 27.62 to 31.80 cm⁻³. The optical absorbance studies were carried out on these glasses to measure their energy band gaps. The absorption spectra of these glasses were recorded in UV-visible region. No sharp edges were found in the optical spectra, which verifies the amorphous nature of these glasses. The optical band gap energies for these glasses were found to be in the range of 2.89-4.20 eV. The refractive index and polarizability of oxide ion have been calculated by using Lorentz-Lorentz relations. The values of refractive index range from 2.13 to 2.42 and those of polarizability of oxide ion range from 6.51×10⁻²⁴ to 7.80×10⁻²⁴ cm³.     

Nuclear and electronic contributions to the third-order nonlinearity in different glasses

Using, a time resolved optical heterodyne Kerr effect experiment along with a Raman light diffusion experiment, we have measured the nuclear (non-instantaneous) and electronic (instantaneous) contributions to the nonlinear index of refraction in tellurite niobium-doped and silicate lead-doped glasses. The experimental set-up and the procedure used to measure the nuclear and electronic contribution are detailed. Our experimental results clearly indicate that the ratio between the instantaneous and the non-instantaneous contribution remain constant while the doping concentration or the temperature of the sample vary. These ratios are ∼5 and ∼10 in tellurite niobium-doped and silicate lead glasses, respectively.     

Optical and thermal properties of doped semiconductor

The knowledge of doping effects on optical and thermal properties of semiconductors is crucial for the development of optoelectronic compounds. The purpose of this work is to investigate theses effects by mirage effect technique and spectroscopic ellipsometry SE. The absorption spectra measured for differently doped Si and GaAs bulk samples, show that absorption in the near IR increases with dopant density and also the band gap shifts toward low energies. This behavior is due to free carrier absorption which could be obtained by subtracting phonon assisted absorption from the measured spectrum. This carrier absorption is related to the dopant density throw a semi-empirical model.     

Static electrical conductivity of a doped semiconductor

This paper evaluates corrections to the static electrical conductivity of a nondegenerate semiconductor, doped with dopants of one type, taking into account the interaction of the charge carriers both with a random field and with lattice oscillations. The results obtained may be generated to the case of an arbitrary random field.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 7, pp. 14–21, July, 1974.The author wishes to express his profound indebtedness to V. L. Bonch-Bruevich for proposing this topic.     

Peripheral phonons and phonon conductivity of the doped semiconductor

The percentage contribution of the peripheral phonons towards the total phonon conductivity of P-doped Ge has been studied with the help of the Ziman expression of the electron-phonon scattering relaxation rate and the Callaway integral of the lattice thermal conductivity. It is found that the percentage contribution of the peripheral phonons increases with the increase of temperature. The entire study is limited to the temperature range 1–5 K.     

Measurements of scan nonlinearity in a scanning electron microscope

A method for measuring the scan nonlinearity of a scanning electron microscope is discussed. This method is tested using a mass-produced microscope and demonstrates good results.     

Nonlinear optical properties of commercial semiconductor-doped glasses

We report new observations made on semiconductor-doped glasses commercially available. We have observed that the modulus of the Kerr susceptibility is proportional to the absorption coefficient below, across and above the gap. We have measured the phase of this susceptibility for various values of the excess energy. We have also observed a blue shift of the absorption edge following pulsed excitation and have measured the diameter of the crystallites to be 70–80 Å. The band-filling model is the most appropriate to account for the nonlinear properties of these glasses.