Energy Characteristics Of Lasers Research Articles

Influence of superradiance in active media with large gains on the energy characteristics of giant-pulse lasers

We carried out experiments which made it possible to substantiate the approximate calculation. An active element of cylindrical shape made from YAG with neodymium (with a 5 • mm diameter) was used to measure the dependence of the value of the population inversion A = Nm/No (where N m is the population of the metastable level in the four-level lasing scheme and No is the concentration of active ions) on the pumping energy, which we shall characterize in the following by the dimensionless parameter K =W:4r32 (where W14 is the probability of a transition from level 1 to level 4 under the action of the pumping radiation, and i/r32 is the probability of a spontaneous transition between the laser levels). For this purpose, the pumping energy corresponding to the threshold for the appearance of stimulated emission was determined in a plane-parallel cavity with various values of the losses ~, and the quantity A =B/o32No (where os2 is the cross section of the lasing transition) was determined. The dependence obtained is presented in Fig. la. From the figure it is seen that the value of the population inversion A has a tendency to reach saturation as K is increased. The restriction of A with increasing pumping energy owing to the influence of superradiance is also supported by the investigation of plots of the dependence of the time-integrated luminescence intensity I in the direction of the longitudinal axis of the sample on the pumping energy obtained by integrating the signal from the light detector. Figure 1 presents plots of the dependence of I on K for crystals of YAG with neodymium having a diameter of 5 x 50 mm for luminescence at the output wavelength Iz and at a wavelength of ~0.9 ~m I2 (the 4F3/2-+4/9/2 transition). As we see from Fig. I, with the same values of K at which the restriction of A (see Fig. la) and the value of I2, which reflect the population of the metastable level, is observed, the value of II increases sharply owing to the significant enhancement of the luminescence at the output wavelength along the sample. (Similar investigations for crystals of YAL with neodymium were carried out in [2].) Thus, the restriction of A with increasing pumping energy is due to the influence of the superradiance.

Influence of mixing effects on the energy characteristics of a self-contained cw HF chemical laser

Boundary layer equations are used in calculations of a self-contained diffusion-type HF chemical laser. Some characteristics of the calculation technique are discussed. An investigation is made of the dependences of the laser energy characteristics on the system parameters. Attention is focused on the influence of factors which control the mixing process of the oxidizer and fuel streams. The results may be used for practical optimization of the energy characteristics of a cw HF chemical laser.

Investigation of the effect of nitric oxide admixtures on the energy and spectral characteristics of an electron–beam–controlled CO laser

It is shown that an NO admixture having a relative concentration of 1 % in the active medium of an electron-beam-controlled CO laser has a comparatively weak influence on the laser energy characteristics but has a substantial influence on its spectrum. In this case, a considerable proportion of the output energy is due to the nitric oxide.

Slot method of extraction of radiation from a laser resonator

The results are given of an experimental investigation of the energy and angular characteristics of ruby and neodymium glass lasers when radiation is extracted through a slot in a resonator mirror. A theory of multimode emission is used in an analysis of the angular structure of the laser radiation.

Characteristics and efficiency of a compact HF laser initiated by an electron beam

A compact hydrogen fluoride laser is described and its efficiency is evaluated. The HF laser is initiated by injecting a 150 kV electron beam into a mixture of SF 6 and H 2 transversely to the laser cell axis. The optimum laser energy characteristics are determined as a function of the beam energy and gas pressure.

Influence of active medium parameters on output energy of an electric-discharge CO2laser

A model is proposed for the calculation of power and energy characteristics of pulse CO2 lasers. Dependence of the output energy of the input energy, and on the composition and pressure of the active medium and obtained and discussed for the case of excitation by a self-sustaining discharge. The best agreement between the calculated and experimental results is obtained at low values of the specific energy input.

Influence of the lifetime of the4I11/2level of Nd3+on the energy characteristics of aQ-switched laser

The rate equations are solved for a Q-switched laser allowing for the lower level lifetime. The equations are reduced to dimensionless variables. The results obtained can be used to calculate the energy characteristics of lasers with all possible initial parameters. The special cases of the influence of the lifetime of the lower level 4I11/2 and of the initial population inversion on the laser efficiency are considered.

Investigation of the reactions of atomic iodine in a photodissociation laser using n-C3F7I and i-C3F7I molecules

A photodissociation iodine laser, employing n-C3F7I and i-C3F7I molecules, was used in a study of the kinetics of the reactions which accompanied the photolysis of these compounds. The results obtained confirmed the earlier observation that the recombination processes involving iodine atoms in the ground state I(52P3/2) had much larger rate constants than those of the corresponding reactions involving excited iodine atoms I*(52P1/2). A study was made of the influence of the structure of the radical R, formed by the photolysis of an RI molecule, on the rate constant of the recombination reaction R + R → R2. The rate constants of several chemical reactions involving iodine atoms and R radicals were determined and the influence of these constants on the energy characteristics of photodissociation lasers was analyzed.

Method for calculating the efficiency of lasers with unstable resonators

Various aspects of the procedure for estimating the energy characteristics of lasers with unstable resonators are discussed. Some results of calculations are given for the general case of an inhomogeneously excited medium.

Influence of the surface treatment of a cylindrical yttrium aluminum garnet crystal on laser energy characteristics

An investigation was made of the influence of the method of mechanical surface treatment of cylindrical neodymium-doped yttrium aluminum garnet crystals on the energy characteristics of lasers usingthese crystals as the active elements. It was established that the best results were obtained for a matte surf ace with a roughness corresponding to a finish of class 8 in accordance with the Soviet Standard GOST 2789-59.

Energy characteristics of millisecond stimulated emission from neodymium-glass lasers

An experimental check was made of the results of theoretical calculations of the energy characteristics of solid-state lasers. The calculations were based on the solution of the radiative transfer equations. The example of optical oscillators and amplifiers in the form of standard GOS-1000B laser units was used to demonstrate the validity of such calculations in qualitative descriptions of the energy characteristics of the millisecond spiking emission from high-power neodymium-glass lasers. The limits of validity of the calculations were established.

Energy and threshold characteristics of chemical lasers

A comparative study has been made of the time sequencing and energy content of the HF laser transitions in the CH3I+N2F4 chemical laser with two different cavity configurations. In one case the cavity is made up of two mirrors, and in the other case of a mirror and a grating. The prime conclusion of this work is that in order to understand the threshold behavior and energy content of multitransition chemical lasers it is necessary to invoke some kind of wavelength-selective cavity. Furthermore, it has been observed that the use of a grating can channel a large portion of the normal total emission (obtained when the cavity consists of two mirrors) into a single transition.