Spectral purity of pulsed dye lasers

High-spectral purity of pulsed dye lasers is required by many experiments. Unfortunately, the dye laser output is usually accompanied by a spectrally broadband background of spontaneous emission (ASE). We have carried out detailed studies of the ASE background using a dye laser operating with an oscillator, pre- and main amplifier.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthday     

Photoacoustic analysis of stimulated emission in pulsed dye lasers

Stimulated emission in pulsed dye lasers was characterized in several experimental conditions by analyzing the changes in the acoustic signals generated in a dye solution, with the dye laser cavity either active or inhibited (i.e., by blocking the optical path or misaligning of the optical components). Pump energy threshold, optimum dye concentration, tuning range and maximum-emission wavelength of a rhodamine 6G dye laser were measured by this method. An approximate model for the photoacoustic signal generation consistent with the experiments is presented.Member of CONICET     

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     

Solvent dependent characteristics of XeCl pumped UV dye lasers

The characteristics of near uv dye lasers pumped with short duration, 308 nm pulses from a XeCl laser are described with particular emphasis on the parameters influencing high average power operation. The solvent is shown to effect the operation of all dye lasers studied, particularly the photochemical stability. Measurements of the efficiency, as a function of the integrated pump energy have been made for a series of dye-solvent combinations. With the best combinations, average output powers in excess of 1W and conversion efficiencies greater than 25% were obtained at a repetition rate of ∼100 Hz.     

Threshold singularities of optically pumped dye lasers

A complete theoretical model for optically pumped dye lasers is studied using the rate equation approach which includes excited singlet and triplet state absorption effects. Closed-form solutions under steady-state conditions reveal a novel nonlinear threshold phenomenon: partial reabsorption of the excited laser light can lead to a discontinuous onset of laser oscillation above laser threshold. Theoretical and experimental results for a transversely and longitudinally pumped rhodamine 6G laser are presented in terms of softmode and hardmode behavior at threshold.     

Pulse generation by distributed feedback dye lasers

Equations describing the pulse generation by distributed feedback dye lasers are derived and solved by analytical methods. The dependence of the laser output on macroscopic parameters is discussed.On leave from the Department of Physics, Friedrich-Schiller-University, DDR-6900, Jena, German Democratic Republic     

Comparison of coaxial- and preionized linear flashlamps as pumping sources for high power repetitive pulsed dye lasers

Prepulse preionized linear flashlamps are well suited as pumping sources of nearly diffraction limited high power dye lasers. 250 kW pulses of 800 ns duration at 10 Hz with a beam divergence of 0.4 mrd were obtained by using a conventional parallel-plane mirror system of 90 cm length. The energy conversion efficiency is 0.3%.     

Theory of passive mode-locking of CW dye lasers with contacted and non-contacted absorbers

A theoretical treatment of the influence of a saturable absorber in close contact with a highly reflecting mirror on a light pulse is given. The shaping of a Gaussian pulse during a single passage through such an absorber is calculated for various absorber lengths. The influence of absorber position and length on the pulse parameters and the stability of a continuously pumped dye laser are investigated. The shortest pulses and the most favourable operation conditions of the laser are to be expected in the case of a short contacted saturable absorber.     

Diode-pumped Tm: YAG solid-state lasers with indirect and direct manifold pumping

We study the continuous-wave (cw) characteristics of both two-manifold and three-manifold Tm: YAG laser pumped at _p 1.8 µm or _p = 0.785 µm and lasing at ₁ = 2.02 µm. The three-manifold rate equations are adiabatically reduced to their two-manifold form. For each pumping scheme, the steady-state rate equations are combined with the cw differential equations for the forward- and reverse-lasing fields and the pump-depletion differential equation. These three coupled cw differential equations are solved analytically. This gives the linear flux-conservation law between the input pump and the laser output, the minimum crystal length, and optimal output couplings. We show that the major difference between these two pumping schemes is due to the different pump effective absorption cross sections and not the two-for-one cross relaxation. Our example shows that the minimum intensity threshold and optimal crystal length are smaller for pumping at _tp = 0.785 µm than pumping at _p 1.8 µm.     

Theory of passively mode-locked cw dye lasers

The circulation of an ultrashort light pulse in a continuously pumped modelocked dye laser with a linear cavity configuration containing the active dye, the saturable absorber and a bandwidth-limiting elements is treated. The steady-state condition that the pulse shape reproduces after each cavity round-trip leads to a nonlinear integro-differential equation for this pulse shape. An approximate method for the solution of this equation not limited to the case of low laser gain and small pulse energies is given. The stable single pulse region and characteristic pulse parameters, as energy, duration, intensity and asymmetry, are considered in dependence on the laser parameters.     

A magnetic tuning system for dye lasers

A new device for magnetically displacing the output mirror of a laser resonator and synchronously tilting an etalon in order to obtain single-mode tuning of a dye laser over a tuning range of at least 10 GHz is described. Comparatively large displacements with good linearity of a coil mounted on a membrane and placed inside the strong magnetic field of a ring magnet are obtained for currents in the order of several hundred milliamperes. Together with etalon flats of appropriate thickness and reflection mounted in the resonator of the laser a versatile instrument for application in intra and extra cavity spectroscopy has been developed.     

Enhanced efficiency and extended wavelength range of dye lasers operated with DCM

It is observed that the efficiency of the DCM dye dissolved in ethylene glycol benzyl alcohol can be enhanced if the dye is preheated at a temperature of 150 °C. Peak powers as high as 1.5 W have been achieved with a single-mode ring dye laser at 640 nm when pumped by 9 W (all lines) from an argon-ion laser. The wavelength region has been also extended beyond both ends of the tuning curve compared to a conventionally prepared DCM dye. Received: 3 September 1999 / Revised version: 9 December 1999 / Published online: 23 February 2000     

Energy transfer in slab dye lasers

A simple model of the energy transfer between a booster dye and the active dye in a flashlamp pumped planar waveguide dye laser is described.Analytical results are compared with experiments for several dyes in the 600–650 nm region.A twofold increase of laser output was found at a wavelength (630 nm) which is of particular interest for several applications.     

Michelson mode selectors and spatial hole burning in single-mode cw dye lasers

Single-mode selection with Michelson selectors in cw standing-wave dye lasers is analyzed. The application of single and double Michelson mode selectors for compensation of spatial hole burning effects is described in detail. Upper limits for the pumping are considered. It is shown that with spatial hole burning compensation, even the single Michelson selector provides sufficient selectivity for high power single-mode operation in linear cavities.     

Quasilongitudinal pumping of dye solution lasers

Journal of Applied Spectroscopy -     

Cesium vapor laser with transverse pumping by multiple laser diode arrays

We have demonstrated a Cs vapor laser that utilizes fifteen laser diode arrays for transverse pumping of the gain medium. A maximum output power of 28 W was achieved with a total optical to optical efficiency of 14% and a slope efficiency of 15%. Transverse pumping allows scaling of such a laser system to a higher power level by simple increasing of the gain medium volume and the number of pump sources.