Optical resonators containing saturable absorbers (saturable resonators) have nonlinear characteristics and can exhibit hysteresis. This is demonstrated experimentally at 10.6 μ wavelength. A saturable resonator is used to switch out the CO2 laser light from its cavity and for repetitive Q-switching. Devices are described to obtain variable length pulses, infinite pulse trains, logical operations on two signals, and memory functions.

The outputs from an 11-element, linear diode laser array with broad stripes have been beam combined into a single beam with a beam quality of ~20x diffraction limited in the plane of the junction. This beam combining was achieved by use of a common external cavity containing a grating, which simultaneously forces each array element to operate at a different, but controlled, wavelength and forces the beams from all the elements to overlap and propagate in the same direction. The power in the combined beam was 50% of the output from the bare laser array.

Measurement of microwave fine structure in OH infrared transitions using frequency mixing with metalto metal infrared diodes

An infrared point-contact diode is used to mix the frequency of a 28.0 μ water laser with that of a 9.3 μ CO2 laser and a K-band microwave radiation. The experiment provides, among several applications, the crucial link necessary to establish a frequency multiplier chain for absolute frequency measurements in the infrared.

A laser-based technique for rapid, anisotropic etching of compound semiconductors is described. Both holes for through-wafer vias and high-resolution diffraction gratings have been made with the process.