Dye Laser Oscillator Research Articles

Narrowband lidar technique for Na temperature and Doppler wind observations of the upper atmosphere

A new two-frequency lidar for measuring mesospheric Na temperature profiles is described that uses a stabilized CW single-mode dye laser oscillator (rms frequency jitter less than 1 MHz) followed by a pulsed dye power amplifier (140 MHz FWHM linewidth) that is pumped by an injection-locked Nd:YAG laser. The laser oscillator is tuned to the two operating freqencies by observing the Doppler-free structure of the Na D2 fluorescence spectrum in a vapor cell. The lidar technique and initial observations of the temperature profile between 82 and 102 km at Ft. Collins, CO are described. Absolute temperature accuracies at the Na layer peak of better than + or - 3 K with a vertical resolution of 1 km and an integration period of approximately 5 min were achieved in this initial experiment. Finally, a multiple frequency technique for the simultaneous measurement of both temperature and Doppler wind profiles is discussed.

Flashlamp pumped narrow-linewidth dispersive dye laser oscillators: very low amplified spontaneous emission levels and reduction of linewidth instabilities

We report on optimized narrow linewidth (138-MHz </= Deltanu </= 360-MHz) flashlamp excited dispersive dye laser oscillators yielding extremely low amplified spontaneous emission levels in the 10(-10) range. In addition, we specify thermal and dye flow conditions where linewidth instabilities, for double-longitudinal-mode oscillation, can be neutralized.

High-power tunable femtosecond laser system using high dispersion prism compressors

A simple high-power tunable femtosecond laser system for ultrafast spectroscopy has been developed. A cavity-dumped, hybridly mode-locked dye laser oscillator is followed by an external compressor consisting of two-stage prism pairs and an optical fiber. The system produces well-controlled pulses tunable in a range of 595–623 nm, with a peak power of 27 kW and a minimum width of 51 fs. As an application, ultrafast optical Kerr response of β-carotene is observed using this source.

Optimium design of a multi-stage dye-laser amplifier pumped with Cu-vapor lasers.

A numerical simulation code, based on the one-dimensional photon A numerical simulation code, based on the one-dimensional photon transport equation, was developedand analyzed to evaluate the performances of Rhodamine 6G dye laser amplifiers pumpedwith Cu-vapor lasers. The upper singlet-state absorption played an important role to determinethe efficiency. The simulation code was applied to optimize a multi-stage amplifier system with apulsed or a CW dye-laser oscillator. The analytical results gave a useful guideline to design ahigh-power pulsed dye-laser system for atomic uranium enrichment.

Experimental test of a four-level kinetic model for excited-state intramolecular proton transfer dye lasers

The nanosecond pulses of a dye laser oscillator based on the excited-state intramolecular proton-transfer reaction (IPT) of salicylamide and 2′-hydroxylphenyl benzimidazole dyes have been studied as a function of several experimental parameters. To explain the operation of this laser a numerical four-level kinetic model was developed until the lasing properties of these dyes, in the presence of a variable oxygen concentration and pumped with a double pulse technique, could be reproduced. This was possible only by assuming that the efficiency of the laser is controlled by the absorption cross-section of a transient state with a lifetime in the nanosecond-picosecond range, which was tentatively identified as a ground state tautomeric species.

Ray transfer matrix analysis of multiple-sprism dye laser oscillators

A ray transfer matrix description of multiple-prism beam expanders used to produce narrow-linewidth emission in pulsed dye lasers is given. The formulae are then applied to describe beam divergence characteristics of a narrow-linewidth multiple-prism grating oscillator. A comparison between theory and measured beam divergence and laser linewidth is provided.

Ray transfer matrix analysis of multiple-prism dye laser oscillators

Ray transfer matrix analysis of multiple-prism dye laser oscillators

Pulsed single-mode laser ionization of hyperfine levels of zirconium-91

We identify a considerable improvement in proposed schemes for isotopic depletion of zirconium-91 on the basis of the atomic vapor laser isotope separation (AVLIS) method. The improvement lies in applying a single-longitudinal-mode dye laser for selective excitation of all hyperfine split levels of the ground state of zirconium-91. High-resolution laser-induced fluorescence spectroscopy of atomic beams of zirconium produced through laser vaporization–supersonic expansion has been used to identify transitions of zirconium with suitable hyperfine structure. Casimir magnetic-dipole and electric-quadrupole coupling constants and isotope shifts have been derived and are reported for five excited configurations. Suitable intermediate levels in a multistep resonance ionization pathway have been identified by two-color resonance ionization spectroscopy. Isotope depletion has been demonstrated on one ground-state-transition ( z F33∘←a F32at 593.7 nm) by using a specially constructed pulsed, single-longitudinal-mode dye-laser oscillator. Prospects and future directions in zirconium AVLIS are discussed.

Optimization of a cw mode-locked frequency-doubled Nd:LiYF_4 laser

Several drawbacks of a cw-pumped mode-locked Nd:LiYF(4) laser are outlined, and it is shown how to overcome them. For the first time, attention is paid to thermally induced astigmatism and its compensation in a Nd:LiYF(4) rod. An optimized system generates an average output power similar to that of a typical Nd:YAG laser, however, with an increased stability and with pulse durations that are significantly shorter. The higher peak power in Nd:LiYF(4) can result in a higher conversion efficiency in a frequency-doubling process, provided the doubling crystal can handle the high average power. It will be demonstrated that a well-engineered Nd:LiYF(4) system may become the preferred choice for many applications, including seeding regenerative amplifiers and pumping synchronously mode-locked dye laser oscillators and amplifiers.

Linewidth instabilities in narrow-linewidth flashlamp-pumped dye laser oscillators

Linewidth instabilities in double-longitudinal-mode (250 MHz </= Deltanu </= 375 MHz) multiple-prism flashlamppumped dye lasers are characterized. It is found that the origin of the instabilities is mainly physical with partial contribution from stochastic processes.

Diffraction-limited single-longitudinal-mode multiple-prism flashlamp-pumped dye laser oscillator: linewidth analysis and injection of amplifier system

In this paper, we present results of a study on a compact multiple-prism Littrow flashlamp-pumped dye laser oscillator. Single longitudinal mode at a linewidth </=375 MHz was achieved in a diffraction-limited laser beam with a divergence of 0.5 mrad at full angle. Output energy was 11 mJ for rhodamine 590 at a concentration of 5 x 10(-5) M. A detailed analysis of linewidth characterization is provided, and results demonstrating suppression of double-mode operation to produce single-mode oscillation are described. Also, we provide experimental evidence of linewidth variations during the laser pulse. A flashlamp-pumped positive-branch confocal unstable resonator was used to amplify the narrow-linewidth emission from the oscillator to an output energy of 600 mJ.

Quasiunimodal tunable pulsed dye laser at 440 nm: theoretical development for using a quad prism beam expander and one or two gratings in a pulsed dye laser oscillator cavity

In the first section of this paper a theoretical discussion is presented for the performance of a pulsed dye laser oscillator cavity, without an intracavity etalon, using the Gaussian beam approximation. Optimal conditions for achievement of narrow spectral linewidth are discussed (location of the grating or of the beam expander). Various configurations of oscillator cavities are investigated, including a dispersive device composed of one grating and one virtual grating. The use of a beam expander is treated. We find that the same spectral linewidth is obtained theoretically for the optical cavity with two gratings as with one grating and a virtual grating. In the second part we describe the performance (in terms of spectral linewidth 1.3-GHz FWHM quasiunimodal structure, divergence of the beam, etc.) of the dye laser in light of the theoretical arguments. The complete laser contains an oscillator stage, a preamplifier stage, and an amplifier stage, each pumped by an UV beam (355 nm) from a pulsed Nd:YG laser.

Single-mode flashlamp-pumped dye laser oscillators

In this paper, we report single-longitudinal-mode operation in a flashlamp-pumped dye laser incorporating a multiple-prism beam expander with the grating either in a Littrow or grazing-incidence configuration. Linewidths in the 260-MHz range were obtained, using rhodamine 590 dye at output energies exceeding 60 mJ. Pulse duration for the multiple-prism Littrow dye laser oscillator was approximately 200 ns (FWHM).

Effects of the laser pulse transverse spatial distribution on multiphoton ionization processes

In this paper we study the influence of the transverse spatial distribution of the laser beam on the estimate of the photoionization cross section for the specific case of two-step photoionization (TSPI) of benzene. In particular, we discuss the sensitivity of the inferred cross section on the multimode transverse operation of the dye laser oscillator.

Optically biased tunable femtosecond dye laser and spectral windowing of the compressed second harmonic of Nd:YAG

We describe a technique for enhancing tunable ultrashort pulse pumped dye laser performance based on the use of "long" pump pulses to optically bias the cavity toward minimal losses. Increases in dye laser output power of 155 percent and powers as high as 125 mW have been measured with pulse durations under 300 fs. Optical pulses as short as 180 fs are reported for this ultrashort pulse pumped dye laser oscillator. We also report the first measurements of the spectral windowing of compressed 532 nm pulses for temporal pulse shaping, in the optimal group velocity dispersion limit. Temporal pulse shaping is demonstrated with small losses in power and minimal pulse broadening.

Amplified spontaneous emission in narrow-band pulsed dye laser oscillators - Theory and experiment

We have investigated the effect of amplified spontaneous emission (ASE) on the spectral and temporal characteristics of narrow-band pulsed dye laser oscillators. The space and time dependent rate equations for the molecular populations and photon fluxes have been solved numerically to study the dependence of ASE on various laser parameters and the effects of ASE on the spectral and temporal profile of the dye laser output. To account for the diffraction losses present in a real dye laser oscillator, appropriate feedback factors for the laser and ASE photon fluxes were introduced into the boundary conditions for the oscillator. These theoretical results have been substantiated by experimental measurements of ASE in a narrow-band pulsed dye laser oscillator. We show that a considerable reduction of ASE in a grazing incidence grating dye laser oscillator can be obtained by appropriately shaping the pump pulse. Oscillations observed in the temporal output of pulsed dye lasers are also discussed.

Synchronous cavity mode and feedback wavelength scanning in dye laser oscillators with gratings

A simple result of scalar diffraction theory is used to derive the round trip phase accrual of a plane wave in dye laser oscillators containing gratings. This is used to determine configurations where the standing wave condition is satisfied at the feedback wavelength throughout an angle scan. We find that at least one such exactly synchronous configuration always exists regardless of oscillator type.

High-repetition-rate high-power variable-bandwidth dye laser

An efficient high-repetition-rate dye laser is described which has a bandwidth that can be tailored to match typical atomic inhomogeneous linewidths. The dye laser is pumped by a 4-kHz 2–6-mJ/pulse copper vapor laser. The total efficiency of the dye laser (oscillator and amplifier) is 45% for rhodamine 6G and 30% for rhodamine B.

Synchronization of a picosecond mode-locked dye laser oscillator–amplifier with a streak camera system

We report a scheme for synchronizing a mode-locked oscillator–amplifier dye laser with a streak camera detection system. A detailed description of the electronics is given. Operational constraints imposed by existing subcomponents of the apparatus are discussed and directions for future refinement outlined.

Spatial and temporal properties of a tunable picosecond dye-laser oscillator–amplifier system

In this paper, we describe a high-power picosecond dye-laser system providing tunable 1.5-mJ pulses with a uniform wave front and Gaussian spatial profile. With the aid of a computer-controlled data acquisition system, we have analyzed for the first time the temporal coherence properties of such a system.