High gain and high peak power in planar waveguide lasers
We report enhanced peak power and gain for pulses in the 10-100 /spl mu/sec range, with specific peak power to 240 kW m/sup -2/ of electrode area at frequencies to 4 kHz. Pulsed small signal gain is increased by a factor of 7 relative to cw/long pulse excitation.
Enhanced peak power and short pulse operation of planar waveguide CO2 lasers
We report a large peak power enhancement and reduction in pulse width for planar waveguide carbon dioxide lasers. Gain modulation through rf discharge power switching produces trains of laser pulses with peak power levels at up to 38 times the cw power level, with a pulse duration as low as 10 μs. Operation at repetition rates in the kHz region preserves the average power (100 W) of the normal cw/long pulse mode of operation. The laser is shown to operate close to the predicted boundaries dictated by thermal loading of the discharge.
Geomagnetic Polarity Epochs: Sierra Nevada Data, 3
Available paleomagnetic and radiometric results for about 60 igneous rocks 3.6 m.y. old or less are consistent with the following geomagnetic polarity epoch time scale: Brunhes normal polarity epoch, 0.0 to 0.85±0.15 million years; Matuyama reversed polarity epoch, 0.85±0.15 to 2.4±0.1 million years; Gauss normal polarity epoch, 2.4±0.1 to 3.35±0.1 million years; Gilbert reversed polarity epoch, 3.35±0.1 million years to (?). A brief interval of normal polarity (the Olduvai event) occurs within the Matuyama reversed epoch at about 1.9 m.y., and a brief interval of reversed polarity (the Mammoth event) occurs within the Gauss normal epoch at about 3.06 m.y. Data for twelve units from eastern California and Nevada, reported here for the first time, are particularly useful in defining the Gauss-Gilbert boundary and for recognizing the Mammoth event.