Resonance radiation trapping effects in CuCl laser

Abstract: Pulsed and continuous‐wave microwaves at 2.45 GHz combined in an Asmussen resonant cavity are used to vaporize, dissociate, and excite copper chloride discharges. Steady state microwaves from 50 to 150 W sustain a microwave discharge which heats and dissociates the copper chloride to a sufficient vapor pressure. A variable frequency (2.45 to 2.60 GHz) pulsed microwave source with pulse widths ranging from 0.5 to 2 ms, repetition rates of 500 to 5000 Hz and a peak output power of 4,500 W then excites the copper atomic states. The two microwave signals are superimposed using a hybrid junction before input into the resonant cavity. Microwave frequencies of the pulsed portion of the signal around 2.50 GHz provided maximum absorption by the discharge. This device is being examined as a potential pump source for a copper vapor laser.

Abstract: It is known that resonance quanta are highly absorbable by normal atoms of the emitting gas; hence, under suitable conditions of gas density the eventual escape of these quanta from a gas-filled enclosure may require a large number of repeated absorptions and emissions. This "radiative" transport of excitation is determined essentially by the probability, $T(\ensuremath{\rho})$, that a quantum traverses a layer of gas of thickness, $\ensuremath{\rho}$, without being absorbed; the dependence of $T(\ensuremath{\rho})$ on the frequency distribution of the resonance line is investigated, and explicit expressions are derived for the cases of Doppler and dispersion broadening. The general transport problem is formulated in terms of a Boltzmann-type integro-differential equation involving $T(\ensuremath{\rho})$; the variational method of obtaining steady-state solutions of this equation is discussed. The theory is then applied to the evaluation of the rate of decay of excitation in an infinite slab; the results are compared with Zemansky's measurements of the decay of radiation from an enclosure of mercury vapor. Finally, the application of the theory to a number of problems concerning excited atoms is discussed briefly.

Abstract: A class of lasers which operates by cyclic excitation and relaxation in atomic vapor discharges is discussed. The required energy level structure for maximum efficiency is described. Pulsed laser action in neutral atomic copper vapor at 5105.54A (58 dB/m, 2 kW peak power) and at 5782.13A (42 dB/m, 0.6 kW peak power) provides experimental verification and promises high efficiency. Pulsed laser action was also observed in ionized calcium at 8542.09A and 8662.14A. Both have saturated gains of 58 dB/m and a total peak power output above 30 W.

Abstract: Superradiant laser emission at 5106, 5700, and 5782 A is reported from pulsed discharges in copper iodide vapor at temperatures near 600°C. This conclusion is supported by pulse shortening of the visible emission and a marked increase in the relative visible intensity compared to the copper resonance radiation as the critical temperature range is approached. Electrical dissociation of the copper iodide, electron impact excitation of the copper atoms, and radiation trapping of the 3248- and 3274-A resonance lines are proposed as the principal inversion mechanisms. Below \sim450\deg C, where insufficient copper iodide is vaporized to provide resonance trapping, the upper laser level lifetimes are ∼10 ns, whereas at higher temperatures trapping is complete and the effective2P 3/2 and2P 1/2 lifetimes are 615 and 370 ns, respectively. The reservoir temperature at which stimulated emission is observed is in good agreement with calculations of the threshold ground-state copper densities required for resonance trapping. These experiments indicate that practical copper laser systems operating at substantially reduced temperatures can be developed provided instabilities in the copper iodide discharges can be overcome.

Abstract: Laser action in copper at 5106 and 5782 A is reported from double pulsed discharges with a new lasant, cupric acetate, at an optimum temperature of 230 °C. Several interesting laser characteristics observed as a function of temperature and delay between pulses are discussed for both transitions.

Abstract: Resonance radiation trapping effects in copper and manganese pure metals and their halides as laser materials have been investigated using Holstein’s theory of resonance radiation trapping. Theoretical calculations have been performed for determining the laser‐starting and optimum temperatures, and dissociation levels in the metal halides. The results are found to be in excellent agreement with the reported experimental values. A detailed discussion of the results has been presented.