Travelling-wave operation of a tunable cw dye laser

A ring cavity configuration for a tunable cw dye laser is described. A substantial reduction of the output bandwidth of the ring laser with increase in power for unidirectional or traveling-wave operation has been demonstrated. The advantages of the ring configuration for single-frequency operation of cw dye lasers are explored.     

Single mode operation of a tunable cw dye laser

Using the differential absorption method the NO₂ concentration within the plume of a smoke stack and over the area of a chemical factory was measured.     

Locking of a cw dye laser to inverted atomic transitions

We have observed narrow line oscillation of an internally pumped cw dye laser at wavelengths which correspond to atomic transitions in the pump laser discharge. At other discharge wavelengths quenched regions in an otherwise broader dye laser output have also been observed. It is believed that the narrow lines correspond to transitions which have gain in the pump laser discharge, while the holes correspond to transition with loss.     

Spectral narrowing of a flashlamp-pumped,waveguide dye laser by amplification of tunable narrow-band cw radiation

Spectral narrowing of the broad-band emission from a flashlamp-pumped dye laser, which consisted of a slab waveguide high-gain amplifier in conjunction with a high-loss resonator, is reported.The pulsed laser oscillator was driven by a cw dye laser oscillating in several longitudinal modes. An energy output up to 10 mJ per pulse has been obtained with a driving power of 10 mW, showing the possibility of substantial power amplification of the narrow-band emission from a cw dye laser.     

Narrow linewidth,tunable dye laser by multiple-prism beam expander

12 mJ, 10-Hz green pulses from frequency doubled Nd:YAG laser was used for pumping Rhodamine 6G in a dye laser based on multiple-prism beam expander. In order to increase the stability of the output pulse, a unique dye cell with variable dimensions of active medium was designed and constructed. By using multiple-prism dispersion theory, conditions for zero-dispersion in two and four-prism beam expander configuration was calculated. In the case of two-prism configuration, tuning range of dye laser was 565–595 nm and the linewidth of pulse at 580 nm was about 1.8 nm and it is in good agreement with the calculated amount of 1.6 nm. Furthermore, using four-prism configuration tuning range of 570–585 nm was measured and the linewidth of output pulse at 575 nm was reduced up to 0.33 nm. This value may be further improved up to 0.22 nm according these calculations. In this arrangement, creation of parasitic modes, aberration in two dimensions and most of the alignment problems with the lens telescopes were resolved.     

Optical pumping experiments using a cw dye laser with a narrow spectral output

An optical pumping experiment on the Na atoms of an atomic beam by means of a continuous wave dye laser is described. The atoms interact at two different regions with the laser beam. In the first region the atoms are optically pumped so that a Zeeman coherence in their substates is produced. In the second light beam the coherence is probed. Any changes in the phase of the eigenfunction of the atom through interaction in a magnetic field, or through collisions, or other effects occuring in the light free section can thus be sensitively detected. The possible applications of the set-up are discussed.     

Direct absorption spectroscopy using a rapidly tunable CW dye laser

Using a recently developed electronically tunable cw dye laser, the spectrum of an absorption sample could be obtained and repeatedly scanned every 10 μsec. The system is potentially capable of monitoring spectral changes in times as short as 10^?7 sec.     

High resolution dye laser spectrometer for measurements of isotope and isomer shifts and hyperfine structure

A high resolution cw dye laser spectrometer with a frequency calibration system of 100 kHz resolution is described. Two examples of measured isotope shifts will be discussed.     

Transform-limited behavior from the synchronously pumped cw dye laser

We report for the first time transform limited behavior from the picosecond synchronously pumped cw dye laser. This is accomplished by the use of an inexpensive, low-loss intra-cavity etalon. The Fourier relationship between pulse frequency width and time duration is shown to be obeyed quantitatively at three different wavelengths. The pulse profile changes as a function of wavelength and does not follow an analytical functionality at any wavelength studied. For each wavelength, the optical cavity length producing transform limited pulses is shown to be the same.     

On the hyperfine spectral lines of an atomic copper vapor laser

The hyperfine structure of energy levels of copper atom and its transition probabilities were considered. The resonance and metastable levels of the copper atom are split into hyperfine structures, due to the magnetic dipole moment and the electric quadrupole moment. In this paper, a succinct introduction to the relevant theory of the hyperfine spectral structure and experimental observations of elemental copper vapor laser is presented.     

Microwave optical double resonance of NO2 with a tunable cw dye laser: Spin-rotation and hyperfine interactions in the 2B2 excited electronic state

Various spin and hyperfine components of the 6₁₆ → 7₀₇ microwave transition in the ²B₂ electronic excited state were observed by microwave optical double-resonance spectroscopy using a tunable cw dye laser near 593 nm. Spin splittings and the hyperfine structure of two levels were precisely determined. Spin-rotation and hyperfine interactions in the ²B₂ state are discussed using these and the previously reported results on the 8₁₈ → 9₀₉ transition. From the hyperfine splittings of the K_a = 0, N = 7 and 9 levels, a value for the Fermi contact interaction constant, (0)_I, of ～50 MHz was determined.     

On the shape of absorption lines in a divergent atomic beam

The influence of the non-negligible width of the light beam on the shape of the spectral line observed in an atomic beam has been investigated theoretically. The expression obtained for the intensity distribution along the absorption line contour is studied for special cases of zinc and mercury atomic beams used in Fabry-Perot interferometry.     

Optical pumping of free atomic ions with hyperfine structure

Free atomic ions with hyperfme structure have been oriented m He buffer gas by absorption of circularly polarized light. ΔF=±1 hyperfine transitions have been measured in the 6² S _1/2 ground state of¹³⁵Ba⁺ and¹³⁷Ba⁺ with an accuracy of 1 part in 10⁷.     

Characteristics of a hybridly mode-locked cw dye laser

We present experimental and theoretical results on the characteristics and random variations of subpicosecond pulses generated by a synchronously pumped cw dye laser with saturable absorber. The analysis of the power spectra indicates rapid fluctuations of the pulse duration of 40–50%, energy fluctuations of 3%, and a jitter of the repetition time of 0.1% corresponding to an absolute jitter of 12 ps. The latter is caused mainly by the temporal jitter of the pump laser. A mismatch of the lengths of the dye and the pump-laser cavity can result in a nonstationary mode-locking regime with a periodic change of the pulse parameters. The interpretation of the experimental results are supported by computer simulations of the pulse evolution process.     

Internal amplification of subpicosecond pulses from a cw mode-locked dye laser

Subpicosecond pulses from a synchronously and passively mode-locked cw rhodamine 6G dye laser have been amplified with a gain of 10–80 in a range of 577–615 nm by a simple method in which the laser medium inside the cavity acts simultaneously as an amplifier pumped by the second harmonic of a Q-switched Nd:YAG laser. Under the good mode-locked condition, there was no appreciable pulse broadening effect due to amplification even in a very short subpicosecond regime, while imperfectly mode-locked pulses were amplified with considerable pulse broadening effect even in the picosecond regime.     

Investigation of the two-photon absorption spectrum of 3,4-benzopyrene by means of a tunable dye laser

The two-photon absorption of the solid solution of 3,4-benzopyrene in methyl polymetacrylate, induced by a tunable dye laser has been investigated. An absorption spectrum in the range of 530–750 nm has been obtained. The dependence of the fluorescence intensity I_F upon the laser power I_F, I_FλI^k_L and the relation k=k(λ) has been i investigated.     

Fine-structure measurements of two-photon transitions in atomic cesium with a tunable dye laser

Two-photon transitions have been observed from the 6²S ground state of atomic cesium to selected higher lying n²D levels up to n = 19. The transitions were excited by a narrowband dye laser pumped by a nitrogen laser and detected by a space charge limited cesium vapor photodiode. The fine structure intervals of the n²D levels for n = 15, 17 and 19 were measured by direct comparison with the ground-state hyperfine interval, and the line strength ratios of the fine-structure components were measured and compared with the predictions of a simple theoretical model.     

Level-crossing under nearly monochromatic excitation by a narrow-band cw dye laser

The shape of level-crossing signals under excitation by a narrow-band tunable dye laser has been investigated. The light of the laser was scattered on a highly collimated atomic beam of Na. The laser radiation (bandwidth about 3 MHz) was fairly monochromatic compared with the natural line-width of the 3 ²P_{$\text{3}\text{2}$} state (10 MHz). The form of the zero-field level-crossing signal of this state depends strongly on the frequency of the exciting radiation. The experimental results agree well with calculated signal shapes.     

Fast frequency control of a cw dye jet laser

For frequency stabilization of a cw dye laser a very fast reacting piezo mirror translator with 350 kHz lowest resonance frequency has been developed. If it is driven by appropriate control electronics it allows to suppress efficiently fast frequency changes of the jet stream dye laser. The remaining frequency jitter is 270 kHz rms for full-bandwidth detection; it drops to a few kHz if a filter time constant of 100 μs is used.