E. G. Burkhardt

cw SUBMILLIMETER LASER ACTION IN OPTICALLY PUMPED METHYL FLUORIDE, METHYL ALCOHOL, AND VINYL CHLORIDE GASES

cw laser action is obtained on two lines in methyl fluoride, three lines in vinyl chloride, and 23 lines in methyl alcohol by optically pumping the gases with various lines of the CO2 laser. The laser wavelengths range from 70 to 700 μm.

CO2 Waveguide Lasers

Compact cw single‐mode CO2 : He : N2 lasers with a 1‐mm‐diam dielectric waveguide discharge tube have exhibited gains of up to 37 dB/m, volumetric power outputs of 15 W/cm3, and saturation parameters of 3600 W/cm2 with a coolant temperature of −70°C. With tap water cooling at 20°C the corresponding values were 24 dB/m, 9.5 W/cm3, and 2100 W/cm2. All of these values are substantially larger than those obtained with conventional CO2 lasers. A 12.5‐cm‐long waveguide tube with an active volume of 0.096 cm3 gave a power output of 1.4 W at −70°C and 0.9 W at 20°C coolant temperature.

Growth of high‐quality GaxIn1−xAsyP1−y by chemical beam epitaxy

GaxIn1−xAsyP1−y epilayers closely lattice matched, Δa/a≲5×10−4, have been reproducibly grown over the whole range of composition (y=2.2x, 1>y>0) by chemical beam epitaxy. The relative sticking coefficient (or equivalently the incorporation efficiency into the solid) of arsenic to phosphorus, i.e., SAs/SP was between 1.5 and 3 depending on the material composition. Such values indicate a very efficient incorporation of phosphorous in this process. Very intense efficient luminescence peaks due to excitonic transitions with linewidths full width at half‐maximum as narrow as 3 meV were obtained. Such a linewidth corresponds closely to the intrinsic linewidth due to alloy broadening in GaInAsP alloys. Furthermore, the photoluminescence spectra revealed that the donor‐to‐acceptor pair recombination was nearly absent. Hall measurements on GaxIn1−xAsyP1−y epilayers lattice matched into InP at 300 and 77 K yielded electron mobility values that agreed closely with theoretical values calculated by using the one‐phon...

cw LASER ACTION AT 81.5 AND 263.4 μm IN OPTICALLY PUMPED AMMONIA GAS

cw laser action at 81.5 and 263.4 μm, corresponding to a rotational transition and an inversion transition in the v2 state of NH3, has been obtained by optically pumping the gas with an N2O laser.

High‐frequency constricted mesa lasers

InGaAsP cw constricted mesa lasers at 1.3 μm are described which have a small‐signal 3‐dB bandwidth of 20 GHz at −70 °C. Large‐signal pseudorandom modulation at 8 Gb/s resulted in 100% optical modulation. The lasers were gain switched at 12 GHz with 100% optical modulation.

ERRATUM: HIGH‐PRESSURE LASER ACTION IN 13 GASES WITH TRANSVERSE EXCITATION

Laser action has been achieved in 13 gases at high pressures using pulsed transverse excitation. A total of 149 wavelengths from 0.8 to 28μ was observed. Pulse lengths were found to lie in the range 0.2–5μsec. Several gases operate at atmospheric pressure and above and promise to give very high power outputs.

HIGH‐PRESSURE LASER ACTION IN 13 GASES WITH TRANSVERSE EXCITATION

Laser action has been achieved in 13 gases at high pressures using pulsed transverse excitation. A total of 149 wavelengths from 0.8 to 28μ was observed. Pulse lengths were found to lie in the range 0.2–5μsec. Several gases operate at atmospheric pressure and above and promise to give very high power outputs.

Resistance and mobility changes in InGaAs produced by light ion bombardment

We have measured sheet resistance and mobility changes for a series of In0.53Ga0.47As layers as a result of hydrogen, boron, and beryllium implantation. We find that boron and beryllium implantation can produce a two order‐of‐magnitude increase in sheet resistance due mainly to a decrease in mobility accompanied by a smaller decrease in the sheet carrier concentration. Hydrogen implantation results in a decrease in sheet resistance due to an increase in electron concentration accompanied by only a small mobility decrease. The increase in sheet resistance due to boron and beryllium implants is not large enough to have obvious application for device isolation.

Beryllium implantation doping of InGaAs

Ion implantation doping of Be acceptors in n‐In0.53Ga0.47As is reported. A significant improvement in peak concentration, depth control, and solubility is achieved with rapid (30 s) thermal anneals compared to conventional 15‐min furnace anneals, resulting in p‐n junction depths less than 1 μm with peak acceptor concentrations greater than 1018 cm−3. Electrical profiles and p‐n junction characteristics are presented.

Mode‐locked high‐pressure waveguide CO2 laser

Active mode locking of a high‐pressure cw waveguide CO2 laser is reported. Pulse widths as short as 3 nsec are obtained. The results are shown to be in good agreement with existing theory.