Implications of spectral hole burning on the manipulation of spatial Goos–Hänchen shift in an atomic cell

We present a new scheme to report on Goos–Hänchen (GH) shift experienced by the Gaussian light beam interacting with an optical cavity filled with four-level sodium atomic medium in the spectral hole burning region with and without Doppler broadening effect. Theoretical atomic density-matrix formalism is employed to obtain the susceptibility of atomic medium while the stationary-phase-theory is used to compute the GH shift in the reflected and transmitted probe beams subjected to control fields. A steep normal slope of dispersion is observed with a maximum and zero probability of transmission and reflection coefficients, respectively, at the regions of the spectral holes burning. In the normal dispersion spectrum at the region of spectral hole burning, positive and negative GH shift is observed, respectively, in the transmitted and reflected light beams. However, at anomalous dispersive regions negative GH shift in the transmission beam and positive GH shift in the reflection beam is observed. The reflection and transmission coefficients as well as the spatial GH shift are the functions of probe detuning, collective phase of control fields, beam incident angle and inverse Doppler broadening effect in the spectral hole burning region. The position and number of spectral holes also depend on the same spectral parametrs as stated above. The study is expected to be useful for optoelectronic devices and optical-clocking applications.     

Spectral Hole Burning via Kerr Nonlinearity

Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality.     

Spectral Hole Burning via Kerr Nonlinearity

Spectral hole burning is investigated in an optical medium in the presence of Doppler broadening and Kerr nonlinearity. The Kerr nonlinearity generates coherent hole burning in the absorption spectrum. The higher order Kerr nonlinearity enhances the typical lamb dip of the hole. Normal dispersion in the hole burning region while Steep anomalous dispersion between the two hole burning regions also enhances with higher order Kerr effect. A large phase shift creates large delay or advancement in the pulse propagation while no distortion is observed in the pulse. These results provide significant steps to improve optical memory, telecom devices, preservation of information and image quality.     

Slow light and saturable absorption

Quantitative analysis of slow light experiments utilising coherent population oscillation (CPO) in a range of saturably absorbing media, including ruby and alexandrite, Er³⁺:Y₂SiO₅, bacteriorhodopsin, semiconductor quantum devices and erbium-doped optical fibres, shows that the observations may be more simply interpreted as saturable absorption phenomena. A basic two-level model of a saturable absorber displays all the effects normally associated with slow light, namely phase shift and modulation gain of the transmitted signal, hole burning in the modulation frequency spectrum and power broadening of the spectral hole, each arising from the finite response time of the non-linear absorption. Only where hole-burning in the optical spectrum is observed (using independent pump and probe beams), or pulse delays exceeding the limits set by saturable absorption are obtained, can reasonable confidence be placed in the observation of slow light in such experiments. Superluminal (“fast light”) phenomena in media with reverse saturable absorption (RSA) may be similarly explained. The article is published in the original.     

BaSO4Sm^2＋晶体的光谱及光子选通烧孔效应

首次报道—种新的无机光子造通光谱烧孔材料——BaSO_4:Sm~ (2+)的烧孔效应.并给出了有关光谱性质的实验结果.     

不同选通条件下对光谱烧孔孔深的研究

本文从理论上分析了低激发密度下,选通光分别为脉冲光和连续光时,孔深随时间的变化,得到可以通过脉冲光烧孔、连续光选通的方法缩短烧孔时间.应用BaFCl_0.5Br_0.5:Sm²⁺(2%)进行了实验,分析了单脉冲烧孔的孔深.     

不同选通条件下对光谱烧孔孔深的研究

本文从理论上分析了低激发密度下，选通光分别为脉冲光和连续光时，孔深随时间的变化，得到可以通过脉冲光烧孔、连续光选通的方法缩短烧孔时间．应用ＢａＦＣｌ０．５Ｂｒ０．５：Ｓｍ２＋（２％）进行了实验，分析了单脉冲烧孔的孔深．     

A saturable absorber, coherent population oscillations, and slow light

The paper presents a critical analysis of publications on one of the methods of creating so-called slow light (light with an anomalously low group velocity) arising due to a high steepness of the refractive index dispersion curve. The method employs, for this purpose, the effect of coherent population oscillations accompanied by burning of a narrow spectral hole in the homogeneously broadened absorption spectrum. The interpretation of the experimental data in the studies under consideration is based on the analysis of the response of a nonlinear medium to a low-frequency intensity modulation of the propagating light beam. We show that all the observations of these papers can be easily interpreted in the framework of the simplest model of a saturable absorber and have nothing to do with the hole burning effect or group velocity reduction.     

Hole-burning NMR in strongly inhomogeneous fields

Different pulse sequences for frequency-selective NMR in the highly inhomogeneous fields of single-sided NMR are explored. A modified Hahn-echo is used to burn a hole in the spectrum of the detected echo. The hole diminishes following molecular dynamics on the scale of the echo time. Preliminary experiments were performed on pure water and natural rubber with the NMR-MOUSE. The results demonstrate the feasibility of hole burning to study slow molecular dynamics by mobile NMR in strongly inhomogeneous magnetic fields.     

光谱烧孔中孔的宽度和深度与烧孔光持续时间的关系

本文由光学Bloch方程出发,讨论了二能级系统光谱烧孔中孔宽和孔深与烧孔激光脉冲持续时间的关系.在强场下短脉冲烧孔中,用π脉冲可以得到足够深且宽度小于稳态值的孔.弱场下,孔深与烧孔时间成指数关系.Bloch方程的修正对上述两种条件下烧孔行为的描述无明显影响.以二能级系统光谱烧孔为基础,讨论了永久性光谱烧孔和光子选通光谱烧孔中孔的行为.     

Coherent hole burnings induced without saturation field in a Doppler broaden four-level N-type atomic system

We display the phenomenon of the hole burning which appearing without saturation field under the effect of different parameters. Theoretically the effect of spontaneously generating coherence (SGC) on the probe polarization spectrum in a Doppler broadened four-level N-type atomic system are investigated when the two driven and probe fields are arranged in copropagating and counterpropagating configurations which play an important role in appearing the coherent hole-burning (CHB) phenomenon. The condition of appearing the hole burning in the polarization spectrum at the presence of spontaneously generating coherence (SGC) and the nonradiative decay rates is that the wave number fields are different.     

Narrow optical hole burning and related effects in ruby

We observed a narrow optical hole burning in ruby whose width (FWHM = 107 kHz) is the narrowest of those reported so far in solids. A hole before reaching its steady state which we call transient hole was used on the basis of theoretical analysis of the hole burning. The first observation of optical wiggles and the detection of superhyperfine structures near zero frequency are reported as two new effects related to the narrow optical hole burning.     

Controllable broadening of zero-phonon lines by means of the Doppler effect and prospects of using spectral hole burning in optical informatics

An attempt is made to extend the spectacular variant of optical informatics efficient at liquid helium temperature—holography based on zero-phonon lines (ZPLs) and spectral hole burning, including time-and-space-domain holography—to higher temperatures, up to room temperature. At room temperature, both optical and Mössbauer narrow ZPLs exist; however, they do not have the inhomogeneous broadening that transforms a ZPL into a broad band, which is necessary for informatics based on light pulses. The idea of producing a band with an appropriate width from narrow ZPLs by using the Doppler effect is advanced. A variant of experimental realization of this idea by means of a scheme with a rotating disk covered by a layer of a material sensitive to spectral hole burning is considered. Numerical estimates were performed for narrow optical ZPLs and for the yet experimentally unconfirmed Mössbauer ZPL in the visible spectral range (dark blue nuclear light) that corresponds to a transition between the two low-lying levels of the ²²⁹Th isomer. For the narrowest optical ZPLs known at present, with a width of about 100 Hz, the estimates give favorable results, in particular, for prospects of realizing a photoelectrically accumulated stimulated photon echo.     

Room-temperature persistent spectral hole burning of Eu(3+) in sodium aluminosilicate glasses

Persistent spectral hole burning has been observed at 77 K, 180 K, and room temperature for Eu(3+) in sodium aluminosilicate glass melted under a reducing atmosphere. In particular, room-temperature persistent spectral hole burning is reported for the first time to our knowledge in Eu(3+) -doped materials. The persistent hole is accompanied by no antiholes and lasts for 1 h at least. The thermal stability of the hole is greater than that of a persistent hole burned for Eu(3+) in sodium aluminosilicate glass melted in air.     

On the possibility of optical measurement of strains by persistent spectral hole burning in an opaque sample

A method proposed for persistent spectral hole burning makes it possible to store (“photograph”) the field structure of dynamic and static strains and to choose an appropriate point of measurement in the bulk of a sample. Another intriguing possibility consists in measuring strains in a material opaque to light. To do this, optical fibers (light guides) should be embedded in the sample and activated by impurities sensitive to hole burning, i.e., having good zero-phonon lines in their spectra.     

The shadow and observation appearance of black hole surrounded by the dust field in Rastall theory

In the context of Rastall gravity, the shadow and observation intensity casted by the new Kiselev-like black hole with dust field have been numerically investigated. In this system, the Rastall parameter and surrounding dust field structure parameter have considerable consequences on the geometric structure of spacetime. Considering the photon trajectories near the black hole, we investigate the variation of the radii of photon sphere, event horizon and black hole shadow under the different related parameters. Furthermore, taking into account two different spherically symmetric accretion models as the only background light source, we also studied the observed luminosity and intensity of black holes. For the both spherical accretions background, the results show that the decrease or increase of the observed luminosity depends on the value range of relevant parameters, and the promotion effect is far less obvious than the attenuation effect on the observed intensity. One can find that the inner shadow region and outer bright region of the black hole wrapped by infalling accretion are significantly darker than those of the static model, which is closely related to the Doppler effect. In addition, the size of the shadow and the position of the photon sphere are always the same in the two accretion models, which means that the black hole shadow depend only on the geometry of spacetime, while the observation luminosity is affected by the form of accretion material and the related spacetime structure.     

Room-temperature grating-based morphological hole burning in Sm2+-doped glass powders

We have observed grating-based morphological hole burning in Sm2+-doped glass powders at room temperature. When photobleaching on the 4f(6)-4f(5)5d transition of Sm2+ is combined with multiple light scattering, holes are produced in frequency and wave-vector domains. The hole profile depends on the amount of light absorption of Sm2+; it sharpens as the absorption decreases. The variation of the hole shape is explained theoretically based on a diffusion approximation.     

光谱烧孔技术

论述了光谱烧孔技术的动力学理论模型 ;介绍了单光子烧孔和多光子烧孔所取得的实验结果 ;讨论了光谱烧孔的发展趋势 :提高烧孔度 ,实现室温烧孔和提高探测及读出时的信噪比。问题的关键在于光致填孔机制的研究。同时提出将它投入实际应用亟待解决的问题 ,即作为一种可能的高密度频域光信息存储手段所亟待解决的问题是开发适应于此技术的新材料 ,深入研究材料体系的烧扎特性     

Observation of ultraslow light propagation in a ruby crystal at room temperature

We have observed slow light propagation with a group velocity as low as 57.5+/-0.5 m/s at room temperature in a ruby crystal. A quantum coherence effect, coherent population oscillations, produces a very narrow spectral "hole" in the homogeneously broadened absorption profile of ruby. The resulting rapid spectral variation of the refractive index leads to a large value of the group index. We observe slow light propagation both for Gaussian-shaped light pulses and for amplitude modulated optical beams in a system that is much simpler than those previously used for generating slow light.     

Persistent hole burning in semiconductor nanocrystals

The persistent spectral hole burning (PSHB) phenomenon was found to occur in many kinds of nanocrystalline semiconductors, such as CdSe, CdS, CuCl, CuBr and CuI, embedded in crystals, glass or polymers. In inhomogeneously broadened exciton absorption spectra of these nanocrystals, the spectral hole and its associated structure were created by the narrow-band laser excitation and were conserved for more than several hours at 2 K. Hole depth grew in proportion to the logarithm of the burning fluence. Thermally-annealing and light-induced hole-filling phenomena were observed. The hole burning takes place by the tunneling process through potential barriers with broadly distributed barrier height and thickness. Unusual luminescence behaviors related to the PSHB phenomena were also observed. They are luminescence elongation with increase of the light exposure and hole burning in the luminescence spectrum. The observed PSHB phenomena are explained by the exciton localization and the succeeding ionization of nanocrystals. The energy of the photoionized nanocrystal is released from the original energy and the new energies depend on the spatial arrangement of the trapped carriers. Quantum confinement of carriers and resulting strong Coulomb interaction between confined carriers and trapped carriers are essential for the energy change. Possible applications of the PSHB phenomenon is discussed.