O. R. Wood

High-pressure pulsed molecular lasers

A review of recent developments in high-pressure pulsed molecular lasers is presented. Included are some experimental results on TEA lasers, E-beam lasers, and lasers using Blumlein excitation. Discussions of the kinetic modeling, the parametric behavior, and the characteristics of uniform discharges in the high-pressure pulsed CO 2 laser are given. Recent results on pulse-initiated chemical lasers, extremely high-pressure lasers, and high-repetition-rate TEA lasers are also discussed. Efforts to control and use the output from these devices are described, and an extensive list of references is given.

Optically pumped 33‐atm CO2 laser

Single nanosecond laser pulses at wavelengths near 10 μm have been obtained by using a pulsed HBr laser to optically pump pure CO2 gas at pressures up to 33 atm in a 1‐mm‐long optical resonator. At pressures above 17 atm, the laser oscillates on the 10.3‐μm R branch rather than on the usual 10.6‐μm P branch.

Transversely excited waveguide gas lasers

This paper summarizes the work done on transversely excited (TE) waveguide lasers since the first proposal in 1973 and reports on the current state of the art. We describe the development of waveguide designs and of techniques for discharge control which permit high-pressure operation and high output power densities to be obtained.

MODE LOCKING OF A TRANSVERSELY EXCITED ATMOSPHERIC PRESSURE CO2 LASER

Mode locking of a transversely excited atmospheric‐pressure CO2 laser has been achieved through the use of a germanium acousto‐optic modulator. Subnanosecond pulse widths and peak powers in excess of 1 MW have been obtained.

Transverse‐Discharge Hydrogen Halide Lasers

Laser action has been achieved in six hydrogen and deuterium halides formed in chemical reactions initiated by a pulsed transverse discharge. A total of 246 wavelengths from 2.6 to 19.7 μm was observed. Nearly 30% of these transitions have not been previously observed in laser action. All of the lasers operate at relatively high pressure and promise to give very‐high‐power outputs.

Photoionization lasers pumped by broadband soft-x-ray flux from laser-produced plasmas

Large population inversions on transitions ranging in wavelength from 109 to 748 nm have been produced in six elements pumped by photoionization through inner-shell and/or multielectron (shakeup) processes with the broadband soft-x-ray flux from laser-produced plasmas. Gain coefficients ranging from 0.25 to 11.5 cm−1 have been measured in He, Ar, Zn, Cd, In, and Xe using the soft-x-ray flux produced by 25–300-mJ, 70-psec-, and 10-nsec-duration pulses from a 1.06-μm laser. Extension of this scheme to Na suggests that a 10-mW average-power laser can be produced at 37.2 nm at a 10-Hz repetition rate by photoionizing Na vapor with the soft-x-ray flux produced with a 1-J, 50-psec-duration pulse from a 1.06-μm laser.

Simple metal-vapor recombination lasers using segmented plasma excitation

A new type of electrically excited laser device has been developed using a new pumping scheme which involves segmented plasma excitation and recombination (SPER). SPER laser action is produced in a metal species when a series of small vaporized plasmas, formed in the gaps between a row of metal electrodes subjected to a high‐voltage pulse, is allowed to expand and recombine. To date, laser action at 17 wavelengths between 0.94 and 1.84 μm in 8 metal vapors has been observed. This device is simple to construct, has a long operating life, and has the potential for high efficiency.

Influence of ion assistance on the optical properties of MgF(2).

The optical properties of MgF(2) films prepared by evaporation and ion-assisted deposition have been determined from transmittance and near-normal incidence reflectance measurements and also from electron-energy loss spectroscopy (EELS). The results show that oxygen-ion assistance leads to higher extinction coefficients for wavelengths <180 nm. Transmission electron microscopy studies show that the crystal grain size of MgF(2) films is not strongly affected by oxygen or argon-ion bombardment. The presence of MgO in the films is inferred from RBS measurements and proposed to be the major factor influencing VUV losses. EELS is also demonstrated to be a valuable technique for determination of optical properties from the near-infrared to x-ray regions of the spectrum.

Vacuum ultraviolet loss in magnesium fluoride films.

The optical constants of evaporated MgF2 films were determined over the 1050–1600-A wavelength range from measured transmittance and near-normal incidence reflectance measurements. The complex refractive index was studied as a function of film deposition conditions and correlated with microstructural examinations by transmission electron microscopy. Absorption by the low energy tail of an exciton band and scattering from inhomogeneities were found to account for the film’s loss in this wavelength range. Both of these factors were determined largely by substrate temperature during the film deposition.

High-gain inner-shell photoionization laser in Cd vapor pumped by soft-x-ray radiation from a laser-produced plasma source

A soft-x-ray-pumped inner-shell photoionization laser has been produced in Cd vapor at 4416 and 3250 A. A gain of 5.6 cm(-1) has been measured at 4416 A, and a reasonably high-energy storage of 0.2 mJ/cm(3) in the upper laser states has been obtained.