Rhodamine 6G Laser Research Articles

High power subpicosecond pulse generation from a synchronously pumped dye laser combined with an external compressor

A new scheme of subpicosecond pulse generation based on a dye laser is described. Output pulses of 15 ps from a rhodamine-6G laser pumped synchronously by a frequency-double mode-locked Nd: YAG laser are compressed into 0.8 ps pulses of 2 MW by two passes of saturable absorber (DODCI) and saturable amplifier (rhodamine-6G). The technique is useful for generating widely tunable, high power repetitive subpicosecond pulses.

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-width dependence on intracavity bandwidth in synchronously mode-locked cw dye lasers

We present a model of the synchronously mode-locked cw dye laser which predicts a square root dependence of dye pulse width on pump pulse width and intracavity bandwidth (ωc). Experiments performed on the Rhodamine 6G laser confirm the ω−1/2c dependence. For a pump pulse width of 100 ps, subpicosecond dye pulses are obtained for intracavity bandwidths greater than 150 Å, and the minimum pulse width is shown to be limited by the bandwidth of the dye to ∼0.5 ps.

A slab waveguide laser formed of glass-clad LiNdP4O12

A 60-μm-thick and 0.5-mm-long LiNdP4O12 slab waveguide laser clad by sputtered SK12 glass was fabricated. Single TE0-mode pulse and quasi-cw laser oscillations at 1.047 μm were obtained by longitudinal pumping with a rhodamine 6G laser and an argon laser, respectively. The round-trip waveguide loss was evaluated from the threshold pump pulse energy to be 0.035 for TE0-mode oscillation.

Generation of tunable continuous-wave ultraviolet radiation from 257 to 320 nm

The generation of tunable cw radiation by sum-frequency mixing the output of a Rhodamine 6G laser and selected output lines of an argon-ion laser in an angle-tuned KDP crystal has been investigated. This technique, coupled with second-harmonic generation of the Rhodamine 6G laser, provides a simple source of cw ultraviolet radiation, continuously tunable from 257 to 320 nm, with a maximum output power in excess of 250 microW and a bandwidth of less than 0.03 nm.

Possible investigation of absorption line profiles by intracavity laser spectroscopy

The profiles of weak absorption lines were determined experimentally by intracavity laser spectroscopy. The use of a rhodamine 6G laser made it possible to record not only narrow but also wide absorption lines whose width was up to 15 cm–1. The error in the determination of the absolute absorption coefficient by intracavity laser spectroscopy did not exceed 20%.

Lithium neodymium tetraphosphate laser

Laser action at λ=1.047 μm is reported in a lithium neodymium tetraphosphate crystal (LNP; LiNdP4O12) pumped longitudinally with a rhodamine 6G laser (λ=5965 Å) or a chopped Ar ion laser (λ=5145 Å). Comparing the measured threshold and round-trip loss of the resonator of the LNP laser with that of the Nd:YAG laser, the effective emission cross section for the ion in the 4F3/2 manifold of LNP is found to be 1.65 times that of Nd:YAG.

Pumping of red continuous-wave laser dyes

Two methods of operating red CW dye lasers are examined. A single laser with a mixture of rhodamine 6G and cresyl violet perchlorate (CVP) is compared with a tandem system in which a rhodamine 6G laser is used to pump a CVP laser. At high pumping levels the tandem system is shown to be superior.

Tunable dye laser pumped transversely by an ultraviolet laser

A report is made of the construction of a rhodamine 6G laser pumped transversely by an ultraviolet nitrogen laser. The width of the spectrum of the dye laser was ~0.002 nm, its output power was 2.5 kW, and it was characterized by a good frequency reproducibility. The dye laser was tunable over a range of 35 nm with a maximum at ? = 590 nm for a given dye concentration.

Pulsed mercury capillary lamps for dye laser pumping: Spectral measurements

Calibrated spectral measurements of the light emitted by a pulsed high-pressure mercury capillary lamp are presented. These pulsed lamps have been used in a previous work to pump a Rhodamine 6G laser. The measurements presented here show a very high efficiency in the blue and near UV part of the spectrum, suggesting that these lamps represent a very attractive pumping source for dye lasers emitting in the blue. In particular, as an example, a computation has been made for a basic solution of 4-MU yielding a spectral efficiency of 24%.

Tunable lasers in ophthalmology.

The present status of laser application in clinical ophthalmology is breifly reviewed. The potentials of tunable dye lasers as retinal photocoagulators are discussed. Selective irradiation of ocular tissues over the full visible spectrum and the simplicity and reliability of recently developed waveguide lasers are the most attractive features of these lasers. Waveguide dye lasers have permitted to set up very compact and simple retinal photocoagulators, with improved output intensity stability and nearfield distribution uniformity. Preliminary results obtained with pulsed Rhodamine 6G laser show that good retinal photocoagulations are obtained at very low output energies.

Influence of the solvent on the output parameters of a cw dye laser

A cw rhodamine 6G laser with a wide-band emission spectrum was constructed. The output power was increased considerably by the use of a mixture of ethyl alcohol and water as the solvent. When the composition of the solvent was optimal, the output power was 70 mW for a pumping power of 2.2 W, which corresponded to an efficiency of 3%. The spectrum of the wide-band emission was recorded and some of its characteristic features were analyzed.

Detection and Quantitation Of Several Atomic Species By Intra-cavity Quenching Of Laser Emission

Abstract Until recently laser research has been the province of the physicist wherein lasers have been utilized extensively as sources of coherent, highly monochromatic energy. The thrust of this research has been to employ the organic solution laser output as an analytical signal from which information about a particular system may be extracted. Preliminary investigations in this laboratory showed that a great number of variables are active in the achievement of lasing from an organic solution. More significantly, concurrent work in this laboratory produced some anomalous results which were subsequently attributed to a cavity defect. This suggested that small energy losses at discrete wavelengths within the resonant cavity of an organic solution laser could result in quenching of broad band laser emission at those specific wavelengths. These considerations led to investigations in which atoms and mlecules were purposefully introduced into the resonant cavity of an organic solution laser.1 A search of the literature revealed that investigators at The National Bureau of Standards had previously observed this phenomenon and had reported on the intra-cavity absorption of a pulsed rhodamine 6G laser emission by sodium vapor.2 In a follow-up paper Keller and co-workers demonstrated the enhancement of absorption for Eu(NO3)3) when placed within the cavity of a rhodamine 6G laser. Concurrently absorption was observed from Ba and Sr in an air-acetylene flame within a dye laser cavity by, Thrash et al.4 Hansch and co-workers5 duplicated the intra-cavity absorption experiment with iodine vapor and compared the sensitivity of this result with measurements obtained from conventional absorption techniques. At about the same time Latz, Wyles, and Green1 reported data which dennnstrated that the extent of intra-cavity absorption for nitrogen dioxide was linearly related to its concentration. Investigation into the use of a laminar flow burner with an air-acetylene flame within a dye laser cavity showed part per billion (ppb) detection limits for sodium as well as the detection of barium and mercury. The completion of these intracavity absorption studies in the visible region of the spectrum yielded the results which are reported here as well as quantitative intyacavity absorption data for Eu+3. In an independent study Konjevic also reported detection of sodium by intra-cavity absorption from an airnatural gas flame6.

Continuous pulse train dye laser using an open flowing passive absorber

Operation of a cw Ar+-pumped rhodamine 6G laser tunable over 900 Å is reported using a thin flowing dye sheet in a new configuration. Passive mode-locked operation tunable over 400 Å has been obtained using an open flowing sheet of DODCI absorber. Multiple-pulse propagation in the laser cavity is observed with increasing pump power above threshold.

The spectral linewidth of a flashlamp-pumped dye laser

The rate equations for the molecular state densities and mode photon densities are set up for a flashlamp-pumped tunable dye laser. These are solved numerically for a typical rhodamine 6G laser tuned by a Fabry-Perot etalon and the results compared with experiment. The untuned dye laser line shape is also calculated and compared with experiment.

Nd-ultraphosphate laser

Laser action at λ=1.051 μm with a bandwidth of 1.4 nm is reported in a 35-μm-thick platelet of a neodymium-ultraphosphate crystal (NdUP) placed within an optical resonator. Longitudinally pumped with a pulsed rhodamine 6G laser (λ=0.58 μm) the room-temperature threshold was 40 μJ and the quantum efficiency slope was ∼18%. Also in glass of the same chemical composition laser action was observed.

Simple dye laser repetitively pumped by a xenon ion laser

A rhodamine 6G laser and a cresyl violet laser emit light pulses of 0.3-μs pulse length and 10-20 W peak power at a rate of 120 Hz when pumped with an inexpensive xenon ion laser.

Passive mode locking of the cw dye laser

Passive mode locking of a cw Rhodamine 6G laser is reported. A stable continuous output of picosecond pulses has been achieved. Correlation measurements using second-harmonic generation (SHG) have determined the pulses to be as short as 1.5 psec. The pulses are transform limited and are wavelength tunable over the range 5900–6100 Å.

Efficient second-harmonic and sum-frequency generation from a flashlamp-pumped dye laser

A tunable ultraviolet light source of high spectral brightness has been generated by frequency doubling of the emission of a flashlamp-pumped rhodamine 6G laser. Second harmonic generation (SHG) has been studied for different bandwidths of dye layer emission between 8 nm and < 10 -3 nm. When the beam spread of the laser was reduced by mode selection, peak power conversion efficiencies between 10% and 18% could be achieved for laser output powers as low as 15 to 25 kW. The influence of the spatial and spectral characteristics of the laser beam on the efficiency of SHG is discussed.

Spectrum and loss of a rhodamine 6G laser pumped by a pinch discharge

Spectrum and loss of a rhodamine 6G laser pumped by a pinch discharge