Passive Shutter Research Articles

Implementation of the Regeneration Regime in the Process of Generating Extremely Short Pulses in an Nd3+: YAG Laser with a Passive Shutter

Implementation of the Regeneration Regime in the Process of Generating Extremely Short Pulses in an Nd3+: YAG Laser with a Passive Shutter

Study of Fe:ZnSe Laser Exited by Diode Side-Pumped Er:YAG Laser

The performance of a Fe:ZnSe laser was investigated in different schemes of excitation by a pulsed diode side-pumped Er:YAG laser. At the temperature of liquid nitrogen, the Fe:ZnSe laser, pumped by a free running 360-μs Er:YAG laser and demonstrated a pulse energy of 53 mJ with a slope efficiency of 42% relative to absorbed pump energy. When operating at room temperature, two optical schemes were considered. In the first one, the Fe:ZnSe laser crystal was pumped by a Q-switched Er:YAG laser with a passive shutter based on an additional Fe:ZnSe crystalline plate, and the cavities of both lasers were independent. In the second scheme, the cavities of the Fe:ZnSe and Er:YAG lasers were coupled, and the Fe:ZnSe crystal simultaneously served as an active element of the Fe:ZnSe laser and a passive shutter of the Er:YAG laser. Pulses with a duration of less than 200 ns and an energy of ~1 mJ were obtained from the Fe:ZnSe laser with a repetition rate of up to 50 kHz. The experimental waveforms of the laser pulses were approximated by rate equations.

Promoting the Range and Range Resolution of a LIDAR (DIAL) System Using a Suitable Pinhole Plasma Shutter

Pulsed transversely exited atmospheric (TEA) CO2 lasers, employed extensively in various applications such as light detection and ranging (LIDAR), have a pulse duration of about a microsecond due totheir nitrogen tail. In order to promote the measurement accuracy and the mean power of the laser pulse, the pulse duration should be shortened. In this research, we present the details of making a passive pinhole plasma shutter for a LIDAR (DIAL) system, which shortens the pulse duration of CO2 lasers from 1.5 μs to 25 ns in air at atmospheric pressure. This instrument increases the range resolution of the LIDAR system from 225 to 3.75 m. Also we show the results of investigation of the clipped pulse duration of the microsecond CO2 laser pulse using aluminum and copper pinhole metal targets with different pinhole diameters (1.5 and 1.8 mm) and at various laser output energies (338 and 309 mJ). Our experimental results show that the aluminum pinhole is more suitable than the copper pinhole for shortening the nitrogen tail of the CO2 laser pulse with a larger output average power. Thus, the range of the LIDAR system, which is proportional to the logarithm of the output pulse power, is increased.

Efficient parametric light generators with intracavity pumping by the radiation of a garnet laser with a passive shutter

The characteristics of parametric light generators with intracavity pumping by the radiation of a garnet laser with a passive shutter have been experimentally investigated. The conversion efficiency of laser radiation with a wavelength of λp=1.064μm strongly depends on the characteristics of the phototropic shutter. When a radiation-colored LiF crystal with initial transmittance T0=0.25 is used in a parametric generator based on a potassium titanyl phosphate crystal at a wavelength of λs=1.91μm, a radiation energy of up to 10 mJ and a quantum efficiency of radiation conversion of Hq≈0.6 are achieved. When a YAG:Cr4+ shutter with T0=0.5 was used, the maximum radiation energy of the parametric generator was 5 mJ, while the conversion efficiency was Hq≈0.3–0.4. In a parametric generator based on potassium titanyl arsenate crystal with λs=1.55μm, the radiation energies corresponding to these shutters were about 7.5 and 5 mJ, while Hq≈0.4–0.6 and 0.25–0.4, respectively.

Erbium-glass slab laser with transverse diode pumping

A slab laser based on borosilicate phosphate glass doped with erbium and ytterbium with transverse diode pumping has been developed and investigated. In the passive Q-switching regime, using a shutter based on a glass-crystalline material with nanosize spinel doped with divalent cobalt ions, the energy of the output radiation was 1.3mJ with a pulse width of 19ns. With active Q switching, the energy of the developed laser was 2.3mJ. The internal optical losses are estimated, and the parameters of the passive shutter are determined.

Spectroscopy and femtosecond laser performance of Yb3+ :Gd0.64Y0.36VO4 crystal

We report for the first time on the efficient continuous-wave and mode-locked laser operation of a diode-pumped Yb:Gd0.64Y0.36VO4 laser. cw output power of 855 mW with a slope efficiency of 45% with respect to the absorbed pump power was demonstrated for the 2.1%-doped crystal. In mode-locked regime with SESAM as passive shutter pulses as short as 100 fs were obtained.

Cr 2+:Cd 0.55Mn 0.45Te crystal as a new saturable absorber for 2 μm lasers

For the first time, to our knowledge, passive Q-switching of 2.09 μm Ho,Tm,Cr:YAG laser has been demonstrated using Cr 2+:Cd 0.55Mn 0.45Te as the saturable absorber. A pulse duration of about 200 ns and an output pulse energy up to 8 mJ were obtained with a Cr 2+:Cd 0.55Mn 0.45Te passive shutter. The ground-state absorption cross-sections for the Cr 2+:Cd 0.55Mn 0.45Te crystal was estimated at 2.09 μm to be 11×10 −19 cm 2, while excited-state absorption was shown to be negligible. Computer simulations of Q-switching exhibits satisfactory agreement with experimental data.

Ultrashort-pulse generation in a passive-mode-locked YAG:Nd laser by means of the resonator-loss-unloading method

The method of generating ultrashort pulses of extreme duration by the controlled resonator-loss unloading of pulsed solid-state lasers with a passive shutter was proposed. The conditions of prolonged maintenance of the threshold operation mode up to the bleaching point of the passive shutter were determined on the basis of calculation of the kinetics of generation. The method was realized for an YAG:Nd laser, and intense ultrashort pulses were obtained with a duration ≈12 ps corresponding to the maximum width of the generation spectrum of a nonselective resonator.

Saturable and excited state absorption measurements in Cr 4+:LuAG single crystals

The performance of a Q-switched Nd-YAG laser using Cr 4+:Lu 3Al 5O 12 (LuAG) as a passive shutter is demonstrated with 35% conversion efficiency between the free-running and the Q-switched mode. From the transmission saturation curves, the ground state and the excited state absorption cross-sections were evaluated. Furthermore, the excited state absorption spectrum of Cr 4+:LuAG in its absorption and emission domains was obtained and characterized. Pulsed laser emission of Cr 4+:LuAG pumped at 1.064 μm was also obtained, though for a short period of time.

Transmission of water under erbium laser irradiation

Water can be used as a passive shutter for Q-switched erbium lasers. The switching mechanism induced in water under irradiation by 2.79- and 2.94- mu m erbium laser light has been studied. It can be explained with a model based on evaporation. Time constants have been measured with a CW HeNe laser at 3.391 mu m. The velocity of the vaporization front is about 10 m/s. This value leads to rise and fall times on the order of 10 mu s in the given geometry. >

Study of a ruby laser with a passive shutter based on a LiF crystal with F 2 + color centers

A large body of current work is dedicated to the study of materials with saturable absorption suitable for passive modulation of the Q of ruby lasers. LiF crystals with F/sub 2//sup +/ color centers are proposed as a passive shutter; however, their prospects to date are unclear. The authors' goal in this paper is a more detailed study of the characteristics of a ruby laser with a passive shutter of LiF:F/sub 2//sup +/ obtained by irradiating LiF crystals with gamma radiation from a cobalt-60 source. Crystals with an OH additive were used to obtain stable LiF:F/sub 2//sup +/. The passive shutter used in the experiments was a parallelepiped 20 x 20 x 9 mm. The initial transmittance of the crystal at the 694 nm wavelength was 41%. To determine these and other parameters of a passive shutter based on these crystals, the authors based their method on measurement of the shutter transmission as a function of the amount of energy of the incident pulsed radiation. The most homogeneous central portion of the beam of the pulsed ruby laser radiation was selected using a diaphragm 5 mm in diameter and was directed to the sample under study.

Repetitive pulse YAG:Nd3+ laser with an unstable cavity and a passive LiF-crystal shutter with F 2 ? color centers

In this article, the characteristic features of the lasing of a YAG:Nd/sup 3 +/ laser with an unstable cavity and a LiF:F/sup -//sub 2/ passive shutter are investigated. In the experiment a diffuse reflector consisting of MS-20 glass is used. The authors site a substantial practical interest in repetitive pulse lasers as the reason for the investigation. It is noted that since the divergence of the radiation from a laser with an unstable cavity and an electrooptical shutter was equal to about 1 mrad in this experiment, the use of a passive shutter made it possible to decrease the divergence of the radiation approximately by a factor of two. The smaller divergence of the generated radiation is obtained together with a bell-shaped time-dependent single pulse and enables operation with high pulse repetition frequencies without appreciable power loss. This indicates the good prospects for the use of passive shutters based on LiF with F/sup -//sub 2/ color centers in repetitive pulse YAG:Nd/sup 3 +/ lasers with an unstable cavity.

Properties of passive shutter based on color centers of LiF crystal

Properties of passive shutter based on color centers of LiF crystal

Self-modulation in a ruby laser with inclined mirrors and a passive shutter

Self-modulation in a ruby laser with inclined mirrors and a passive shutter

Holographic total-internal-reflection selector for tunable lasers

A new holographic selector, operating on the basis of total internal reflection, is described. An analysis shows that this selector has a higher angular dispersion than the devices available at present and this is combined with lower losses inside a laser resonator. A method is given for the calculation of the parameters of a selector operating in the range of wavelengths (0.2–1.2μ) emitted from tunable lasers. This selector uses holographic volume phase gratings recorded in dichromated gelatin films whose optical strength is 2–4 J/cm2 at λ = 1.06μ for pulses of τp = 10 nsec duration. Frequency selection and wideband tuning are reported for a neodymium-glass laser. The width of the spectrum does not exceed 0.7cm–1 in the spiky regime. Single-frequency emission, tunable in a range exceeding 200cm–1, can be obtained in the Q -switched regime (switching by a passive shutter).

Effect of the excited states of a bleachable agent on the dynamics of the development of giant-pulse emission in a laser with a passive shutter

Effect of the excited states of a bleachable agent on the dynamics of the development of giant-pulse emission in a laser with a passive shutter

Dependence of mode kinetics in a laser with passive shutter on spectral characteristics of the phototropic substance

Dependence of mode kinetics in a laser with passive shutter on spectral characteristics of the phototropic substance

Effect of the lifetime of the excited state of a passive shutter on the power of single-pulse laser action

Effect of the lifetime of the excited state of a passive shutter on the power of single-pulse laser action

Efficiency of a ruby laser with a passive shutter as a function of the type of illuminator employed

Efficiency of a ruby laser with a passive shutter as a function of the type of illuminator employed

Effect of thermal distortions of a passive shutter on the operation of a ruby laser having periodic action

Effect of thermal distortions of a passive shutter on the operation of a ruby laser having periodic action