A novel pumping arrangement for tunable single picosecond pulse generation with a N2 laser pumped distributed feedback dye laser

A novel excitation scheme for a N₂ laser pumped distributed feedback dye laser is described. The dye laser generates 80–100 ps pulses with a time-bandwidth product better than 0.6. Several tuning methods are proposed, and a number are investigated experimentally. Continuous tuning over a 50 Å range without mode-hopping is demonstrated.     

Generation of tunable picosecond pulses in a simple distributed feedback dye laser under N2-laser pumping

Simple possibility of single tunable picosecond pulse generation in a conventional inexpensive distributed feedback dye laser (DFDL) is demonstrated. It is shown that when a TEA N₂-laser is used for pumping no diffraction grating is necessary in the DFDL optical scheme for operation in the picosecond regime. Hence wide-range spectral tuning from 357 to 665 nm was easily achieved. When pumped with a 0.6 ns 40 kW pulse of the TEA N₂-laser the DFDL generated pulses as short as 7 ps with time-bandwidth product better than 0.6 and peak power ? 10 kW. At a repetition rate of 50 pps the shot-to-shot energy stability of a single picosecond pulse was ±18% at ±7% stability of the TEA N₂-laser.     

Nine-thousand-fold pulse shortening by an excimer laser-pumped cascade of two distributed feedback dye lasers

Transform-limited single pulses of 2.6 ps and 1.7 ps duration are generated in the red spectral region by an excimer laser-pumped cascade of two distributed feedback dye lasers. Compared with the 15 ns-long excimer pumping pulse, these pulse durations mean pulse shortening of 6000 and 9000 times, respectively.     

Line narrowing of a distributed feedback dye laser using external frequency selective feedback

Frequency selective feedback, employing a mirror and etalon, applied to a distributed feedback dye laser has reduced the linewidth of the emitted radiation by a factor of up to twenty. Criteria used for choosing suitable etalons are discussed.     

First-order distributed feedback dye laser effect in reflection pumping geometry

Tunable distributed feedback lasing output based on reflection grating configuration instead of the traditional transmission one was realized from rhodamine 6G (R6G)-doped ethanol and 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl)-4H-pyran-(DCM)-doped methanol. Pure gain coupling and additional index coupling were obtained in R6G-doped ethanol and DCM-doped methanol, respectively. The tuning, which was found to be independent of the refractive index of the lasing media, went through the entire stimulated emission band for the two cases. Dual-peak lasing emission indicative of the existence of an index grating was observed in DCM-doped methanol. The interval between the two peaks increased with pump energy.     

N2F4 as saturable absorber of CO2 laser radiation

Tetrafluorohydrazine induces passive Q switching in a continuous-wave CO₂ laser in both the P and R branches of the 10.4 μ system, showing comparable effectiveness on all the accessible lines. At higher pressures, this gas forces the laser to oscillate in the 9.3 μ system in non frequency-selective cavities.     

Interferometric studies of 3371 Å N2 laser

Experimental fringe visibility curve of a 3371 Å N₂ laser is presented. A theoretical fit using 19 stronger spectral components is generally in reasonable agreement with experiment but seems to require correlations and fluctuations in the N₂ laser theory.     

Frequency tunability and temporal characteristics of a DAMC distributed feedback dye laser

The frequency tunablity characteristics of a simple prism configuration distributed feedback dye laser (DFDL) pumped by a low pressure nitrogen gas laser are described. Tunability is studied as a function of the refractive index of the dye solution and also as a function of the angle of the interfering beams of the pump laser. The tunability range for the dye studied is from 440 to 480 nm with a spectral width of 0·1 Å and the time duration of the DFDL pulses was 50 ps.     

Tea N2 UV laser with reduced spectra

The effective laser action with the reduced spectra from the N₂ UV laser at 1 atm N₂ with the multichannel transverse strimer discharge excitation of nanosecond duration is described.     

Some considerations on the design of a high-power N2 laser

The design of a high-power transverse discharge N₂ laser is reported. TThe overall maximum efficiency of the laser is 0.51%— thought to be the second highest value reported so far. Details of the pressurized and free-running type spark gap switch and certain parametric studies are also given.     

Photodissociation of N2F4 by a nanosecond CO2 laser pulse

Photodissociation of N₂F₄ by a strong nanosecond CO₂ laser pulse was studied by probing the interaction volume with both UV and IR beams. Up to 20% of the molecules were found to be dissociated into NF₂ during the first few nanoseconds following the passage of the pulse.     

Far-infrared hydrazine laser pumped by an N2O laser

We have used an N₂O laser to optically pump N₂H₄ molecules in a far-infrared cavity and observed 17 new laser lines in the wavelength range 93.0 to 374.2 μm, the 136.8 μm line pumped by 10P(16) being a doublet. We measured the frequencies of the laser lines by heterodyne mixing of the far-infrared radiation with radiation from two frequency-stabilized CO₂ lasers.     

Radiofrequency spectroscopy of AsH3 inside a CO2N2O laser cavity

The method of radiofrequency spectroscopy inside a CO₂N₂O laser cavity has been applied to the observation of pure nuclear quadrupole resonance, A₁-A₂ transitions and two-photon transitions of AsH₃. From the assignment of these transitions some coincidences between laser lines and Δk = 3 transitions in the ν₂ band and Δ|k ? l|; = 3 transitions in the ν₄ band have been assigned. The quadrupole coupling constant eqQ and its rotational dependence χ_J, χ_K and χ_d, and the spin-rotation constants C_N and C_K for the As nucleus have been determined for the ground state. The effective values of eqQ has been determined for the ν₂ and the ν₄ states.     

N2…HF的结构及其氟化氢谐振频率的变化

应用密度泛函理论方法(B3LYP)和QCISD方法,对N2…HF弱结合复合体系在不同的基组下进行abinitio计算,得到了该复合物分子分别在QCISD及B3LYP水平下的平衡结构为:RNN=0.1104nm,0.1095nm,RNN=0.2198nm,0.2094nm和RHF=0.0922nm,0.0931nm,计算了复合物中HF的谐振频率为3899.399cm-1以及HF谐振频率红移量为62.755cm-1,所计算的结果与近期的实验数据和理论值相符合,还考查了不同基组和方法对N2…HF弱结合体系的影响.     

分布反馈激光特性的实验研究

研究了以脉冲YAG倍频激光泵浦Rh6G染料,产生分布反馈激光振荡的辐射光谱、转换效率、时间过程以及可调谐特性;发现在大于泵浦阈值下的分布反馈激光输出的多谱线结构与双脉冲辐射现象,以及分布反馈激光脉冲变窄的自开关效应.作为详细的实验观察和分析.     

A short resonator dye laser pumped by a travelling wave N2-laser

A tunable dye laser is described, which is pumped by 300 ps pulses from a travelling wave N₂-laser. Due to the short resonator length pulses with only 50 ps duration are emitted.     

Two orthogonal polarized wavelengths generated in a N2-laser pumped dye laser

Outputs at two wavelengths with orthogonal polarizations are generated in a N₂-laser pumped dye laser by a simple method. The light leaving the laser cavity at the side exit of the polarizing Glan-Thompson is redirected into the cavity via an additional mirror and a second Glan-Thompson. Depending on its polarization light is travelling different paths and may hit the grating at different angles. In this way feedback is produced for two separate light beams and lasing can take place at two wavelengths simultaneously.     

20 ps pulse generation by an excimer laser pumped double self-Q-switched distributed feedback dye laser

The behaviour of an excimer-laser-pumped distributed feedback dye laser (ELP DFDL) using a mixture of saturable absorber and laser dye as an active medium was studied. In a DFDL self-Q-switching occurs because of the population inversion dependence of the feedback. If the DFDL contains absorber saturation of the absorption by the leading edge of the created laser pulse also causes Q-switching. As a result of this double self-Q-switching, mixing a saturable absorber into the laser dye, the laser pulses become shorter and more stable. This was demonstrated experimentally. Mixing Rhodamine B into the dye solution of a Coumarin 153 ELP DFDL, a six-fold reduction in the pulse duration and a more than two-fold reduction in the pulse energy instability were observed. The experimental results were in good qualitative agreement with the predictions of a simple rate equation model.     

Wing profile measurements of the Na-doublet lines in C2H2/O2/N2, H2/O2/N2 and H2/O2/Ar frames at 1 atm

Fluorescence-excitation (wing) profiles of the Na-D doublet lines were measured over a wavelength range extending from 0.3 to 200 Å from the line center for the red D₁ and blue D₂ wings and from 0.3 to 3 Å for the red D₂ and the blue D₁ wings, respectively. The line profiles were determined with the aid of a tunable CW dye-laser as a background source by measuring the total fluorescence intensity observed on detuning the laser wavelength. The flames were premixed, laminar, shielded flames at 1 atm, with temperatures ranging from 1860 to 2270 K; N₂ and Ar served as diluent gases. The line core and near-wing profiles (i.e. the region covering 0.3<Δλ<7 Å for the outer wings and 0.3<Δλ<3 Å for the inner ones) in all of the flames studied appeared to have the same frequency dependence, regardless of the nature and concentrations of the gases used. The blue D₂-line profile followed an unexpected (-2.2) law, while the other three profiles obeyed the theoretically expected (-2) law (the dispersion profile function). The line profile in the Δλ range between the impact and quasistatic regions was found to depend on the main perturbers involved. We found that the far blue D₂- and red D₁-wings in the Ar-diluted H₂/O₂ flame obeyed the (-$\text{5}\text{4}$) and (-$\text{3}\text{2}$) laws, respectively, as predicted by the quasi-static theory for the Lennard-Jones interaction. For the N₂-diluted C₂H₂/O₂ and H₂/O₂ flames, we did not find these wing dependences in the Δλ range investigated.     

分布反馈量子级联激光器光栅反馈特性北大核心CSCD

为探究Bragg光栅结构对TM模反馈特性的影响,利用有限时域差分法对具有TM模的分布反馈(DFB)量子级联激光器Bragg光栅结构进行仿真研究。重点分析了侧向耦合光栅的光学特性以及光栅侧壁倾角对光栅反射谱、损耗的影响及原因,并探究了光栅刻蚀深度及占空比与TM模的耦合系数、损耗的关系。结果表明有效折射率是影响Bragg波长的主要因素,而光限制因子是不同周期的侧向耦合光栅结构耦合系数产生巨大差别的原因,当光栅侧壁倾角90°时镜面损耗最小。光栅周期、占空比、刻蚀深度与耦合系数的关系表明:这些参数不仅影响光栅的相对介电常数,也会对光限制因子产生作用,从而影响耦合系数的大小;耦合系数与刻蚀深度具有正比关系,大周期光栅耦合系数随占空比的变化率较小。对光栅光反馈特性的理论研究有利于提升对DFB量子级联激光器的认识,促进激光器性能的提升和发展。