Rate equation simulation of temporal characteristics of a pulsed dye laser oscillator

A time-dependent, two-dimensional (in space) rate equation model of a transversely-pumped pulsed dye laser oscillator, which incorporates transverse pump intensity variation in the presence of intracavity dye laser radiation, is proposed to understand and predict its temporal behaviour. The model yields output pulses which agree well with experimental results using rhodamine 6G and kiton red dyes. The shape, amplitude and temporal position of the simulated pulse within the pump pulse vary dramatically across the tuning range of each dye depending on the relative gain and loss values.     

A study on the control of dye solution temperature on the line-width and wavelength stability of a copper vapour laser pumped single mode dye laser

This paper presents a study on the line-width and wavelength stability of a single mode narrow line-width (≈ 100 MHz) dye laser pumped by a copper vapour laser, with and without precision temperature control of dye solution. The single mode dye laser system was based on a specially designed SS metal dye cell and grazing incidence grating (GIG) dye resonator with intra-cavity double prism beam expander and etalon. A high precision wavelength-meter was used to record the line-width and frequency stability data. With the coarse dye solution temperature control of 23 ± 2 °C, dye laser line-width varied in a periodic fashion (in every 30 s) between 100 and 770 MHz. Frequency stability was ± 215 MHz (1 min). This is attributed to switching from single to double mode due to temperature induced cavity length change. For the precise dye solution control of 23 ± 0.1 °C, the periodic variation of the line-width was removed completely and the line-width was always ≤ 100 MHz. The frequency stability also improved to ± 42 MHz (1 min). It is established that the dye temperature control is very crucial for achieving, highly frequency stable single axial mode operation.     

Locking of a flashlamp-pumped dye laser at small injection powers

Experiments have been carried out on the injection-locking of a pulsed dye laser to an argon-laser-pumped CW dye laser of 50 MHz linewidth without longitudinal mode matching. With the inclusion of a Fabry-Perot etalon within the ring laser arrangement of the pulsed laser, the initiation of injection locking and saturation occur at low injection powers.     

Laser intracavity absorption: A numerical and experimental study with a pulsed dye laser

A flash pumped dye laser (Rh6G+Methanol) has been used to study the intra-cavity absorption of I₂ vapour over a wide range of extinctions and over a selected range of laser energies. A computer model based on the characteristics of the experimental laser provides values for quantitative comparison with the experimental ones. Reasonable agreement exists between the numerical computations and the experimental findings.     

Design criteria and operating characteristics of a single-mode pulsed dye laser

We have designed and tested a pulsed single-mode dye laser for spectroscopy experiments. The dye laser is pumped by a 6 kHz copper vapor laser to produce up to 230 mW average power at over 5% efficiency in a nearly diffraction limited beam. The dye laser pulse closely resembles the 30 ns pump pulse. Using an electronic servo loop, the 60 MHz wide line can be scanned, without mode hopping, through the 16 GHz permitted by the travel on the piezo driven mirror mount.This work was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-78     

Operational characteristics of a dye Q-switch for a pulsed ruby laser

This paper presents the results and analysis of experiments carried out on a dye Q-switch to evaluate its operational characteristics. The work was performed on a ruby laser, Q-switched by cryptocyanine in methanol solution. Investigations of performance with regards to pump energy, dye absorbance, output energy and timing of pulse emergence are graphically presented. These results were used to derive the efficiency of Q-switching for varying dye absorbance. Finally, optimization of the Q-switch performance for different requirements of the laser is considered.     

Physics and technology of tunable pulsed single longitudinal mode dye laser

Design and technology demonstration of compact, narrow bandwidth, high repetition rate, tunable SLM dye lasers in two different configurations, namely Littrow and grazing incidence grating (GIG), were carried out in our lab at BARC, India. The single longitudinal mode (SLM) dye laser generates single-mode laser beams of ∼400 MHz (GIG configuration) and ∼600 MHz (Littrow configuration) bandwidth. Detailed performance studies of the Littrow and GIG dye laser resonators showed that GIG dye laser results in narrower linewidth and broad mode hop free wavelength scanning over 70 GHz. In this paper we present experimental studies carried out on the high repetition rate SLM dye laser system.     

宽谱染料激光器的数值模型及实验验证

应用染料激光器半经典理论,数值模拟了脉冲染料激光器双频及宽谱共增益区的谱线竞争效应,与实验结果符合较好.在双频相关调谐工作条件下,调谐范围增大近25％.在宽谱工作条件下,随着输出耦合损耗增大,谱线宽度逐渐减小. 关键词： 染料激光器 半经典理论 谱线竞争     

Single mode operation of a narrow bandwidth dye laser using a single prism, grazing incidence grating long cavity

The single mode pulsed dye laser is an attractive tool for many spectroscopic applications. Long cavity tunable dye lasers generally operate in multi-longitudinal modes within the bandwidth of gain profile. Single longitudinal mode oscillation can be obtained by either making the cavity short enough or introducing an additional loss mechanism, in which all modes but one have a gain less than their loss. A new technique to achieve single mode operation in a long cavity dye laser, based on Rhodamine 6G dye in ethanol and ethylene glycol solution, pumped by a high repetition rate copper vapor laser, is reported. This laser, which operates in three modes in grazing incidence grating configuration (cavity length of 16 cm), has been made to lase in single mode by increasing the loss in the resonator through beam walk-off.     

On the coherence measurement of a narrow bandwidth dye laser

In this paper, we report a new technique for spatial and temporal coherence measurement of narrow bandwidth sources. In particular, coherence measurement of a narrow bandwidth dye laser using Young’s double slit method and the Fabry–Perot interferometer has been carried out. In the spatial coherence measurement, a central fringe visibility of 0.85 was observed, and from this measurement, the dye gain medium source size was estimated. The variation in the visibility with slit separation (0.1–3.0 mm) for different source sizes (0.1–0.2 mm) was also analyzed. The temporal coherence length of the tunable dye laser was measured to be 10 and 60 cm for multimode and single-mode operations, respectively. The technique, in general, can also be used for spatial and temporal measurement of broadband spectrum source.     

Determination of some characteristics of a ruby laser operating in the pulsed mode

Threshold time and pulsation frequency of a ruby laser are studied experimentally as a function of pumping power. Results are compared with theoretical calculations. The absolute value of the probability of pumping quantum absorption is determined, and the minimal energy introduced into the ruby rod is estimated. It is shown that it is possible to use nonstationary characteristics for determining laser parameters.     

A theoretical and experimental study of fluctuations of the optical parametric oscillator

Twin beams generated by OPOs show quantum noise reduction. For type I crystals they reduce in the degenerate case to a single mode, which below threshold exhibits some degree of squeezing. In the nondegenerate case squeezing occurs in the spectrum of their intensity difference. After a theoretical analysis of their spectral properties in both non- and degenerate cases, measured intensity noise correlation and single beam spectra are discussed for pump powers up to 14 times the threshold value.     

加长棒脉冲钕玻璃激光器异常实验现象理论研究

以激光原理为基础, 以大量精确的实验数据为依据;考虑被忽略的自发辐射的影响, 对加长到抽运腔外的钕玻璃棒, 未受到抽运, 反而产生光放大异常实验现象的机理进行了理论研究.理论研究结果与实验结果基本相符.     

A theoretical study on the melting of a finite slab with a pulsed laser

Calculations of the spatial and temporal temperature distributions in the molten layer thickness, the still solid part and in the backward surface of the finite slab were carried out during the irradiation with a pulsed laser. The two-dimensional Laplace integral transform technique has been applied to obtain the mathematical expressions for these temperature distributions and the molten layer thickness as a function of the melting time. The derivations have taken into account the temperature-dependent absorption coefficient of the irradiated surface and the cooling. As an illustrative example, computations were carried out on a finite aluminum (Al) target.     

An experimental and theoretical study of pyrrolidine pyrolysis at low pressure

Pyrrolidine serves as a model substance for a series of saturated nitrogenated heterocycles in plants, including certain amino acids such as proline and hydroxyproline. Thus the pyrolysis of this compound was investigated regarding the increasing interest on biofuels. The pyrolysis of pyrrolidine diluted with 95% argon was studied in a flow reactor at 40 mbar over the temperature range from 950 to 1450 K. Isomer-specific assignment and quantification was performed using molecular-beam mass spectrometry and ionization with tunable synchrotron vacuum ultraviolet radiation. The prominent decomposition pathways were analyzed based on the quantified mole fractions of pyrolysis species. Computations including an ab initio calculation and kinetic modeling for the primary fuel decomposition were used to refine the analysis and reveal the combustion chemistry of this saturated heterocyclic compound. Based on the theoretical calculation, a new pathway for the isomerization reaction pyrrolidine → CH₂CHCH₂CH₂NH₂ via a diradical intermediate was proposed. The rate constant calculations showed that this channel has a large contribution to pyrrolidine pyrolysis.     

Photophysical and laser characteristics of pyrromethene 567 dye: Experimental and theoretical studies

Narrow-band laser performance of alcohol solutions of pyrromethene 567 (PM567) and rhodamine 6G (RH6G) dye was investigated using a home-made GIG-configured dye laser, excited by the second-harmonic radiation (at 532 nm) of a pulsed Nd:YAG laser. Higher laser efficiency was observed with PM567 dye (∼23% peak) in comparison to the commonly used RH6G dye (16.5%), in spite of much lower fluorescence quantum efficiency of the PM567 (0.83) vis-à-vis RH6G (0.98) dye solutions in ethanol. First principle-based electronic structure calculations were performed on PM567 dye in the ground (S ₀) and excited states (S ₁) using density functional theory to elucidate the structure and photophysical properties of the dye.     

A theoretical study of the evaporation induced by a pulsed laser in a finite slab

The two-dimensional integral Laplace transform technique has been applied to get the temperature distributions in the molten layer, the solid part and in the backward surface of a finite target irradiated with a pulsed laser. Formulas for the time dependence of the evaporated part and the molten layer thicknesses of the target were found. This is accomplished by considering the temperature dependence of the absorption coefficient of the irradiated surface as well as the chemical reaction. As an illustrative example computations were carried out on an aluminum (Al) target.     

Single longitudinal mode interaction between a uranium atomic beam and a modified Hänsch-type pulsed dye laser

Laser-induced fluorescence is used as a diagnostic tool for testing the tuning between a longitudinal mode of a nitrogen-pumped dye laser and a uranium spectroscopic level in an atomic beam. According to a simple resonator model, the tuning instabilities can be ascribed to thermal drifts in the dye-laser system. Problems encountered in attempting a single mode scanning are also described.The work described in this paper was carried out at the ENEA Laboratory while P. Benetti was assigned to this Laboratory (1981)     

Interaction and fragmentation of pulsed laser induced microbubbles in a narrow gap

We investigate the interaction dynamics of an existing stable microbubble B1 and another laser induced nearby expanding microbubble B2 in a thin ink sheet between two glass slices. The fast expanding B2 causes anistropic compression of B1 with a forward penetrating jet. In the subsequent expansion stage of B1, the gas associated with jet protrusion to the opposite edge of B1 and the nonuniform surrounding flow field induce necking with transverse inward jetting from the side lobes, which further interact with the axial jet and lead to the final fragmentation into smaller bubbles. At small interbubble distance, the backward interaction from B1 first leads to the pointed pole of the expanding B2 and then a backward jetting during its collapsing. The strong interaction can merge the two bubbles with complicated asymmetric intermediated patterns.     

Theoretical analysis and experimental investigation of pulsed tunable forsterite laser

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