Mode-locking of cw dye laser using externally modulated pumping laser

A new mode-locking method of tunable dye laser is described. This simple and practical method requires only an external intensity modulator to the pumping source. After the simple analytical considerations, the experimental work was done using an Ar laser pumped Rhodamin 6G dye laser and an acousto-optic modulator. As results, stable continuous trains of mode-locked pulses were obtained throughout in the ordinary lasing range 570–630 nm. The pulse width, estimated to be 30–50 ps by SHG autocorrelation measurements, is limited by the bandwidth of Lyot filter used. It is also shown experimentally that this method can be applicable for the suppression of the growth of double pulses in passive mode-locking with saturable absorber (DODCI).     

Investigation of the spectral content of a cw CO laser output using a high-resolution scanning Fabry-Perot interferometer

The use of a scanning Fabry-Perot interferometer of variable length (variable resolution) for investigating the output of a cw CO laser is reported. Under experimental conditions required to achieve maximum power it was found that the laser output consisted of two or more simultaneously occuring transitions due to the overlapping nature of the vibration- rotation bands. The frequency differences between these transitions were measured to an accuracy of 0.01 cm^-1. Operation of the CO laser on a single vibration-rotation transition was obtained by controlling the laser gain with the experimental variables of discharge pressure, gas temperature, and optical alignment. An alternative approach of obtaining monochromatic radiation, by using a Fabry-Perot interferometer as a frequency selective filter external to the CO laser, is reported.     

Astigmatically compensated cw dye laser resonators using lenses

The compensation of the astigmatism of Brewster-angled dye cells can be performed with lenses as well as with spherical mirrors. The advantages of cw dye laser resonators using lenses lie in the linear configuration of the optics and the convenient adjustability of astigmatism compensation. An output efficiency of 30% already at 1.6W pumping power has been observed. In addition, ring laser resonators with lenses have been investigated and they delivered up to 400 mW single mode power in travelling wave operation at less than 2 W pumping power.     

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.     

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.     

A grating tuned cw dye laser

We report on the operation of a rhodamine 6G cw dye laser involving a simple tuning mechanism capable of achieving high output powers (～500 mW) and resolving power (0.004 nm) close to the Doppler limit for a range of light gases. The system employs a 600 line/mm diffraction grating external to, but coupled with a high Q laser cavity; continuous tuning over 50 nm of the fluorescence spectrum of the dye was obtained.     

A high-resolution cw dye laser spectrometer

The construction and utilization of a high-resolution cw dye laser spectrometer is described. The laser incorporates pressure tuned intra-cavity etalons enabling the single mode output laser frequency to be tuned more than one nm in a continuous scan. In the scan the laser jumps from one cavity mode to the next in ～ 50 MHz steps. In comparison to molecular Doppler widths this mode jumping is negligible. As an example of the use of the instrument, a high-resolution absorption spectrum of molecular iodine between the sodium D lines is presented. A unique frequency counter provides the calibration of the absorption spectrum.     

Difference frequency generation with a synchronously mode-locked cw dye laser system

The generation of continuous trains of tunable infra-red pulses by the nonlinear mixing of the wave-lengths available from a self-contained synchronously mode-locked cw dye laser is described. The factors determining the optimization of the process are identified and their roles demonstrated.     

High-resolution spectroscopy with and frequency stabilization of a cw dye laser

The hyperfine splittings of the Na D₁ and D₂ lines were investigated using a single mode cw dye laser. The light of the laser was scattered by the atoms of an atomic beam and the fluorescent light was observed as the frequency of the laser was tuned across the D lines. The Doppler width of the atomic beam was reduced to about 2.5 MHz so that the absorption width of the atoms of the beam was essentially determined by the natural width of the 3²P_1/2 and 3²P_3/2 levels, which is about 10 MHz. Since the linewidth observed for the hyperfine transitions was 30 MHz, most of the hyperfine components of the D₁ and D₂ lines could be resolved. In another experiment the frequency of the dye laser was locked to a hyperfine transition of the D₁ line. The observed variation of the output frequency of the dye laser was less than ±1.5 MHz. In addition, the intensity of the dye laser was controlled to about 10⁻³, using an electro-optically variable transmission filter.     

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.     

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.     

A tunable,frequency-doubled cw dye laser using an RDP crystal

We report a c.w. intracavity, frequency doubled, rhodamine B dye laser using an RDP crystal 5 cm long. Generated uv powers up to 15 mW are obtained in a single direction with a linewidth of 2 GHz over the range 314–318 nm. A conversion efficiency of about 1.25 × 10^-3 W^-1 is measured.     

Near room temperature cw CO laser with a high-power single-frequency output

A relatively simple semi-sealed-off CO laser which operates near room temperature is described. An intra-cavity grating is used to select single- line output powers of about 2W.     

A high-power single-mode cw dye ring laser

Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.     

All-fiber picoseconds MOPA laser with a narrow spectrum output

we report an all-fiber picoseconds MOPA laser with a narrow spectrum output in this paper. The repetition rate of the seed source is increased to ??1 GHz with a unique all-fiber device to suppress nonlinear effects, and a small core gain fiber is used in the power amplifier to support the less transverse mode. Three cascaded amplifiers are adopted to amplify the signal light, and the maximum output power is 30 W with an optical conversion efficiency of 73.9%. The 6 dB spectral linewidth just extends from 0.89 nm of the seed to 1.34 nm at the max output.     

Saturated absorption experiments using a free running CW dye laser

The hyperfine structure of some new iodine lines has been observed over the tuning range of Rhodamine 6G (5800–6200 Å), using a free running, single mode cw dye laser. The resolution obtained in this experiment allowed to calculate the hyperfine constants of the excited state (³π₀⁺) of iodine with an accuracy of 2% for the quadrupole coupling constant and 50% for the magnetic one.     

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.