P. J. Maloney

Optical bistability at a nonlinear interface

Under suitable conditions, the boundary between a linear and a nonlinear (Kerr effect) medium should have a reflection coefficient which exhibits hysteresis as a function of optical intensity. We present the first experimental evidence of this effect. Experiments were performed using ∼1‐ns ruby laser pulses incident on a glass‐CS2 boundary.

Use of a liquid suspension of dielectric spheres as an artificial Kerr medium

We present the derivation of scaling relationships that describe the behavior of liquid suspensions of dielectric spheres as nonlinear optical media and report results of four-wave mixing experiments that are in good agreement with these predictions.

Experimental studies of a nonlinear interface

We describe the results of a detailed experimental study of the reflectivity of a nonlinear interface under the influence of intense ruby laser pulses incident in a Gaussian beam at grazing angles. The nonlinear interface was the interface between a linear optical material (glass) and a nonlinear material with a positive optical Kerr coefficient (CS 2 ). Optical hysteresis was observed as a function of incident light intensity. The nonlinear reflectivity showed behavior which differs from the predictions of previously published plane-wave calculations. We interpret our results with the aid of a numerical analysis of a two-dimensional Gaussian beam case.

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.

Waveguide TEA laser

We describe a miniature transverse‐excitation CO2 laser in which the 10.6‐μm laser radiation is confined within a hollow rectangular‐cross‐section dielectric and metal waveguide. Using a flowing mixture of CO2, N2, and He we have obtained laser action at pressures up to 1 atm, and pulse repetition rates as high as 4 kHz.

The POPOP dye vapor laser

We report a comprehensive study of the operation of a laser using the organic scintillator dye POPOP in the vapor phase. Laser operating parameters have been determined, and we describe tuning experiments which demonstrate an oscillation range of 25 nm. Gain measurements as a function of wavelength and time are reported for transverse pumping with the 337.1-nm output of a pulsed N 2 laser. The quantum efficiency has been measured as a function of temperature and pump wavelength, and a preliminary study has been made of the effect of buffer gases on the quantum efficiency and the gain. Spectral condensation measurements show 90 percent of the broad-band laser output can be obtained in a 1-nm band-indicating that even in a dilute vapor, the thermalization time of the laser levels is \gg1 ns. We conclude by discussing the implications of these results for the achievement of an electrically pumped dye vapor laser.

Photodecomposition in POPOP dye vapor lasers

Abstract Experimental evidence is presented which shows that the premature termination of dye vapor laser gain observed in optical pumping experiments is due to photodecomposition. Addition of up to 4 atm of buffer gases was found to have little effect.

Discharge pumping of dye vapors

We report the results of a study of discharge-excited dye vapors. For 20 dyes, fluorescence output was measured as a function of buffer gas, temperature, and discharge parameters. Although fluorescence efficiencies as high as 6 percent were obtained at low power levels, saturation effects limited the output fluorescence to values corresponding to gains of less than 0.2 cm-1.

Excitation of transversely excited CO2 waveguide lasers

Using a preionization scheme based on the Malter effect, small‐signal gains ≳5%/cm at 10.6 μm ahve been produced in a 1‐mm2‐cross‐section waveguide CO2 amplifier at total operating pressures of 100–760 Torr. Comparisons are made between this preionization scheme and those using electron beams.

Measurement of electronic optical Kerr coefficients.

We describe a degenerate four-wave mixing technique for measuring optical Kerr coefficients. This technique permits discrimination between fast and slow (thermal) nonlinearities. We report results for a number of long-chain organic materials.