Multiwavelength pulse generation in semiconductor-fiber ring laser using a sampled fiber grating

A novel multiwavelength scheme has been demonstrated using a sampled fiber grating in semiconductor-fiber ring laser. By using semiconductor optical amplifier as an inhomogeneously broadened gain medium, three wavelength channels of 10 GHz are simultaneously generated. The number of the lasing channels can be changed through the polarization state adjustment in the cavity.     

Effect of inhomogeneous broadening of submonolayer quantum dots on the generation of vertical-cavity laser with saturable absorber

The experimental dependences for a laser based on submonolayer quantum dots (QDs) without an absorber were used to calculate the energy characteristics of a semiconductor laser based on QDs and quantum wells with a saturable absorber under bistable lasing conditions; the data obtained make it possible to implement a monolithic version of this laser. All of the mechanisms of carrier relaxation and QD filling, which are important for experiment, are taken into account. The effect of inhomogeneous QD broadening over resonant frequency is considered. The laser mode shift that is caused by an increase in the pump current is found to limit the lasing power. It is shown that the choice of active and passive layers with inhomogeneously broadened QDs makes it possible to obtain bistable lasing in the entire range of available pump currents.     

非均匀展宽对超短激光脉冲传播特性的影响

用建立的"预报校正-四阶龙格库塔"数值算法研究了非均匀展宽二能级体系中超短激光脉冲的传播特性。计算结果表明,非均匀展宽线型的线宽对光脉冲传播会产生调制作用。当线宽大于脉冲的频谱宽度时,脉冲面积演化与面积定理相符且脉冲传播平稳;但随着线宽的减小,脉冲面积演化会越来越偏离面积定理,脉冲传播不再平稳并出现"拖尾"振荡。脉冲主峰的峰值和脉冲的传播速度也受到线宽的影响。     

非均匀加宽单模激光器的最佳透射率

给出四能级系统非均匀加宽单模激光器最佳透射率的表达式和分布曲线,并与均匀加宽单模激光器最佳透射率进行了比较.叙述了非均匀加宽单模激光器的特点.     

Ensemble of asymmetric quantum dots in a cavity as a terahertz laser source

The possibility of establishing a terahertz laser generation at a transition between the dressed states formed by the interaction of an intense optical field with an ensemble of asymmetric quantum dots (QDs) in a high-Q terahertz cavity is discussed. It has been shown that the population inversion in the system of dressed states is achieved owing to spontaneous relaxation of the excited state of the QDs. The set of Maxwell–Bloch equations for the difference between dressed-state populations, polarization, and population of the cavity mode has been analyzed in the mean-field approximation. The lasing conditions have been clarified and the possibility of controlling the terahertz radiation intensity has been studied, including the case of an inhomogeneously broadened ensemble of QDs.     

Erbium-doped twin-core fibre narrow-band filter for fibre lasers

Theoretical analysis of a recently experimentally demonstrated erbium-doped twin-core (ErTCF) fibre saturable-absorber-based narrow-band tracking filter is presented. Basic qualitative characteristics of the filter are deduced from an analogy with an ideally inhomogeneously broadened saturable absorber while the effect of wide band saturation of absorption due to spatial overlap of individual spectral components of the radiation is studied in detail using a numerical model based on coupled mode theory, resolved in space and frequency. The effect of the input power, twin-core fibre length and laser operating wavelength on the spectral characteristics of the filter is investigated.     

Numerical solutions to 2D Maxwell–Bloch equations

Rare-earth-doped crystals contain inhomogeneously broadened two-level atoms. Optical propagation and nonlinear interaction in the crystals can be described by the Maxwell–Bloch equations. We show a consistent numerical approach that solves Maxwell’s equations by using the FFT-finite difference beam propagation method and the Bloch equations by using the finite difference method. Numerical simulation results are given for an off-axis 3-pulse photon echo.     

Energy transfer and Anderson localization

The temporal decay characteristics of the donor fluorescence for inhomogeneously broadened optical lines is shown to be a direct determination of excitation localization, in the Anderson sense.     

On experimental potentialities of correlation analysis of the inhomogeneously broadened spectra

The potentialities of the correlation technique with respect to extracting the homogeneous line profile from an inhomogeneously broadened spectrum are analyzed by computer simulation. The signal-to-noise ratio for autoconvolution of the homogeneous line profile, obtained by statistical processing of an array of realizations of the inhomogeneously broadened spectrum for different experimental conditions and different values of parameters of the system is calculated. A general form of the dependence of the signal-to-noise ratio on the magnitude of the accumulated signal is established. An interpolation formula that expresses this dependence in an analytical form is obtained and a simple procedure is proposed that allows one to plot this dependence for specific experimental situations.     

How to achieve lasing in a system with the strong lifetime broadening of working levels?

To minimize and put into an experimentally reachable domain the coherent optical pump intensity needed for radiation amplification on a transition between strongly lifetime broadened levels, an inversionless lasing scheme is suggested. Such a scheme can be used, for example, to achieve lasing in quantum dots with lifetime broadened levels.     

Tuning characteristics of asymmetric inhomogeneously pumped quantum-well lasers

An analysis of the power-current and tuning characteristics of asymmetric multiple-layer inhomogeneously pumped quantum-well lasers with mode selection in the external resonator was performed. It is shown that the choice of the parameters of the barrier and active layers of the laser heterostructure and optimization of the dispersion characteristics of the selective element of the external resonator make it possible to realize continuous tuning of the lasing wavelength in a wide spectral range at a practically constant output radiation power. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 687–692, September–October, 1999.     

Non‐electromagnetically induced transparency mechanisms for slow light

We show how the pump‐induced sharp holes in homogeneously or inhomogeneously broadened absorption line shapes can be used for the production of ultra‐slow light. We present a detailed discussion of underlying concepts and results on the pump power dependences of the group index and the bandwidth–delay product. Further, we discuss experimental results, which are in agreement with theoretical predictions.     

Steady pulse propagation in an inhomogeneously broadened resonant medium

Steady propagation of a single pulse in an inhomogeneously broadened resonant medium is studied. 2π-pulse solutions which are slightly different from those given in the literature are reported and it is shown that π-pulse solutions do not exist.     

The homogeneous,pure electronic linewidth in the spectrum of a H2-phthalocyanine solution in n-octane at 5 K

Measurement of the homogeneous width of the pure electronic transition by the hole-burning method in the contour of a narrow (3–4 cm^-1) inhomogeneously broadened component of the 0-0 multiplet of H₂-phthalocyanine in n-octane at 5 K gives Γ₀₀?0.03 cm^-1.     

Self-pulsing in two-cavity optical bistability

We discuss two serially coupled ring cavities which contain media modelled by an ensemble of homogeneously broadened two-state atoms. This system produces pulsed outputs for appropriate CW inputs and values of the cooperativity parameters in the absorptive regime. In particular, self-pulsing occurs when both stable and unstable steady-state output versus input characteristics are everywhere monotomic with positive slope. An analytic requirement for this self-pulsing is obtained in the absorptive case.     

Maps of Broadband Quantum Memory Based on an Atomic Frequency Comb

Optics and Spectroscopy - The influence of the parameters of an inhomogeneously broadened optical transition in the shape of an atomic frequency comb on dispersion effects in the quantum-memory...     

Laser dye stability part 8

A 3-parameter dye laser degradation equation is introduced that has been based upon a theoretical analysis of a laser oscillator. The new equation and the 4-parameter empirical laser degradation equation used previously in this series are further developed to allow calculation of the lifetime of a dye solution for any fraction of laser output degradation. These lifetime equations are shown to be dependent upon the input energy per pulse and the threshold of lasing. The new 3-parameter equation allows the degradation constants to be determined with less change in laser output than did the original 4-parameter empirical expression.     

掺Nd3+激光玻璃的激光窄线选择激发

本文利用可调谐脉冲染料激光器的窄线输出,在低温和室温下,激发掺钕碲、锗、硅、磷酸盐玻璃和氟铍玻璃的⁴I_9/2→⁴G_5/2(²G_7/2)不均匀增宽吸收带。观测了荧光衰减对激发波长的关系,从而研究在不同玻璃基质中,处于不同格位的Nd³⁺离子的衰减特性以及他们之间的相互作用情况。 关键词：     

Spectral-line asymmetry in double-output-cavity lasers

The aim of this work is to show that the output from a double-output laser cavity exhibits distinctive features, manifesting themselves through typical asymmetry in the corresponding spectral-line shapes. Such asymmetry in an inhomogeneously broadened gas laser usually appears with a clear, but unpredictable shift of the maximum intensity level either towards the high or low frequency sides with respect to line centre. In the case of a double-output laser, the spectral profiles show opposite shifts. This means that when the maximum intensity of one output moves towards the high frequency side of the profile, the maximum intensity of the other moves towards the low frequency side. This gives rise to a frequency shift with respect to the Lamb-dip for a classical laser. On the theoretical side, we apply the standard disturbed Gaussian beam model to provide a quantification of the frequency shifts obtained at both sides of the system.     

Parametric characterization of Gaussian beams propagating through active media

On the basis of the intensity moment formalism, within the thin-sheet approach, the beam width, the beam quality and the kurtosis parameter of a Gaussian beam propagating through active media are investigated. The analysis considers both the homogeneously and inhomogeneously broadened cases. The dependence of the above three parameters on the small-signal gain, saturation intensity and input beam size is studied. The validity of the thin-sheet approximation for the range of propagation distances and physical parameters of the system is also discussed.