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.     

Comparative study of spectral narrowing of a pulsed Ti:Sapphire laser using pulsed and CW injection seeding

We report a comparative study of a pulsed as well as continuous-wave (cw) injection seeding of a Ti:Sapphire laser pumped by aQ-switched frequency-doubled Nd³⁺:YAG laser for achieving narrow spectral bandwidth. The results have indicated that the Ti:Sapphire laser using either a pulsed or a cw injection seeding could achieve efficient energy extraction in a narrow spectral bandwidth. In the case of pulsed injection seeding, the injection energy required for the complete injection seeding critically depended upon the timing of the Ti:Sapphire laser with respect to the delayed onset of the slave laser. On the other hand, in the case of cw injection seeding, the spectral bandwidth of the Ti:Sapphire laser was efficiently narrowed down to approximately 0.01 cm^–1 with an injection power of less than 1 mW. In both types of injection seeding, characteristics observed experimentally were compared with those obtained by a numerical simulation code based on the one-dimensional rate-equation model.     

A high-power subpicosecond distributed feedback dye laser system pumped by a mode-locked Nd: YAG laser

The design and operation characteristics of a distributed feedback dye laser (DFDL) system pumped by the second harmonic of a flashlamp pumped mode-locked Nd: YAG laser are described. The DFDL oscillator facilitates a large tuning range with nearly Fourier limited pulse durations of about 1.6 ps. The combined action of saturated absorption and amplification results in a pulse shortening to about 600 fs, with small fluctuations in the pulse duration. Output pulse energies of more than 400 J are achieved, corresponding to a peak power of more than 650 MW. Since the dye amplifiers are pumped by pulses of only 25 ps duration the amplified spontaneous emission (ASE) is very low, typically less than 10^–4.     

Locking of a flashlamp-pumped dye laser at small injection powers

Experiments have been carried out on the injection-locking of a pulsed dye laser to an argon-laser-pumped CW dye laser of 50 MHz linewidth without longitudinal mode matching. With the inclusion of a Fabry-Perot etalon within the ring laser arrangement of the pulsed laser, the initiation of injection locking and saturation occur at low injection powers.     

Color center laser pumped by a flashlamp-pumped dye laser

A reliable, pulsed, color center laser is described which provides a pulse energy up to 0.4 mJ in a wavelength range from 2.4 μm to 3.3 μm at a bandwidth below 20 GHz. A simple, broadband, flashlamp-pumped dye laser is used as the pump source. A new transverse pumping scheme of F-centers is described using hydrogenated color center crystal which allows to pump color center lasers with high energy pump pulses.     

A subpicosecond dye laser pumped by a xenon ion laser

A pulsed xenon ion laser has been used to pump a rhodamine 6G dye laser utilizing a ring resonator. The dye laser has been passively mode-locked; a pulsewidth of 0.5 ps and a 50 kW peak power have been obtained.Work partly supported by Italian C.N.R.     

Two-wavelength operation of a femtosecond ring dye laser

We report on two-wavelength operation of a CPM ring dye laser employing Rhodamine 6G as gain medium and a new styryl dye as saturable absorber. Two trains of femtosecond pulses at different wavelengths are simultaneously generated under proper alignment of the laser. The secondary pulse train is attributed to the laser action of the absorber dye. Auto- and cross-correlation measurements are performed to determine the temporal characteristics of the laser in the double mode-locking regime.     

Automatic wavelength control of a flashlamp-pumped dye laser

This paper describes a technique for automatically tuning a flashlamp-pumped dye laser to the sodium D₂ line with a precision of ±2 pm (0.02 Å). The same technique could be used for tuning to other emission lines for which a monochromatic source of reasonable intensity is available. A slight modification of the method would enable the laser to be accurately tuned within a range ±10 pm (0.1 Å) of the given emission line.     

Emission spectrum of concentrated dye solutions excited by high-power laser radiation

Emission spectra of concentrated (~10¹⁸–10¹⁹ cm^–3) ethanol solutions of Rhodamine C excited by high-power (~10²⁵–10²⁶ cm^–2s^–1) laser radiation were measured. The emission spectrum consists of two narrow bands (with half-widths of ~200–300 cm^–1). The long-wavelength band was interpreted as cooperative spontaneous emission, and the short-wavelength band was assigned to the amplified spontaneous emission. The ratio of their intensities depends on the dye concentration and the pump power density. The ratio of band intensities is assumed to be determined by the dephasing rate of excited molecules responsible for cooperative spontaneous emission.     

Automatic alignment of a high-power CO2 laser resonator

An on-line, electronic feedback approach for automatic alignment of a laser resonator is described. A measure of the resonator alignment error is derived by partitioning a 1% sample of the laser output into quadrants, and using standard electronic circuits to compare the average power present in each quadrant. A motorized X — Y alignment system is then used to implement the alignment changes required to maintain optimum output quality from the laser. The system is shown capable of stabilizing the output power in each quadrant of the beam to within about 2% of the optimum level.     

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.     

Talbot外腔压窄线阵大功率半导体激光器输出谱宽

线阵半导体激光器（LDA）内部发光元周期排列,基于Talbot效应,改进传统Littrow外腔窄线宽系统,在Littrow外腔中置入反射率为20%平平镜构成Talbot外腔以进一步窄化激光器输出谱宽,并将外腔窄线宽输出通过铷池进行吸收实验。实验结果表明：铷池对Tablot外腔输出吸收系数比Littrow外腔吸收系数相对提高42.9%,说明Talbot外腔能有效提高外腔输出谱宽的均匀性,提高半导体激光器泵浦效率。     

Line narrowing of a distributed feedback dye laser using external frequency selective feedback

Frequency selective feedback, employing a mirror and etalon, applied to a distributed feedback dye laser has reduced the linewidth of the emitted radiation by a factor of up to twenty. Criteria used for choosing suitable etalons are discussed.     

Coherence and beam geometry of a superradiant dye laser

This paper reports the observation of a well defined radiation mode emitted from a superradiant dye laser pumped by a pulsed nitrogen laser. Beam geometry and spatial coherence of the dye laser are studied in connection with the pumping geometry. It is shown that under favorable pumping conditions most of the excited molecules radiate into the same spatial mode by stimulated emission. The associated mode structure is also calculated based on a model of a properly phased dipole distribution. The calculated emission pattern reproduces the observed far field pattern closely. Work supported in part by CNPq and FINEP.     

Tuning characteristic of flashlamp-pumped dye laser with oxygen

The effect of oxygen in the flashlamp-pumped tunable Rhodamine 6G dye laser is experimentally studied. It becomes clear that the laser tuning range is shifted by adding oxygen in the dye solution.     

Coherent spectroscopy with a distributed feedback dye laser

A simple and flexible distributed feedback dye laser source pumped by the harmonic of a mode-locked YAG laser is described. Measurements of dephasing times of isotopic and hot bands in CS₂ liquid exploiting both the frequency and time-resolution of this source are reported.     

Full-automatic broad-band wavelength control of a pulsed dye laser

A full-automatic wavelength controled pulsed dye laser has been developed. With the control system, dye laser oscillations of nanosecond pulses are tuned to any wavelength in the visible or scanned in any sweep mode keeping the nearly transform-limited bandwidth of 0.45 GHz. A mechanical tuning of the wavelength is employed, such that the motion of three wavelength selectors is synchronized to give a smooth and precise wavelength control. The basic principle underlying the tuning scheme, various requirements to be met in system construction, and the practical performance of automatic wavelength control are described in this paper.