Dye Laser Cavity Research Articles

A Mode-Locked cw Dye Laser

The operation of a mode-locked cw dye laser is described. A stable output of repetitive 55-psec pulses has been obtained with an acousto-optic loss modulator in the dye-laser cavity. Pulse widths have been determined by autocorrelation measurements using second harmonic generation in ADP.

Enhancement of Absorption Spectra by Dye-Laser Quenching*

A new technique has been developed to enhance the detection of absorption spectra of weak absorbers. Preliminary experiments, which illustrate the technique, are described. An organic-dye laser normally emits a continuous spectrum with a bandwidth of 2–10 nm. The effect of placing an absorbing-gas sample inside a dye-laser cavity results in laser quenching at those wavelengths where the sample absorption exceeds a minimum threshold absorption. The threshold for absorption quenching appears to be very low; absorption of the order of 0.5% can cause spoiling of laser action at the absorbing wavelengths and displacement of laser emission to wavelengths where absorption is below the critical switching level. Detection limits for atoms and molecules by means of absorption spectroscopy inside a laser cavity can be more than two orders of magnitude lower than those attainable through conventional absorption spectroscopy. Experiments with I2 and sodium both inside and outside the cavity of a rhodamine 6-G laser are described. A qualitative consideration of the proposed mechanism indicates that the technique can be significantly improved with further development.

Dye Lasers

A dye laser uses a fluorescent organic dye in liquid solution, or in a polymer, as the active medium. The device may be excited either by a flashlamp or with a giant-pulse solid-state laser. The broad fluorescence linewidth of a dye and the large variety of dyes available permit the construction of a tunable laser operating throughout the visible spectrum. Furthermore, use of a liquid active medium facilities cooling of the laser for operation at high repetition rates. The gain and power output performance of the dye laser is greater than that of the gas laser and is comparable to that obtained from solid-state lasers. Factors which influence the gain of the dye laser and the excitation power required to reach threshold are reviewed. Tuning by means of dispersive elements in the dye laser cavity is discussed. The results of mode-locking experiments are described. Also, consideration is given to the possibility of obtaining CW operation of the dye laser.