Gasdynamic light guide: high power density transmission measurements

The refractive-index gradients in the gas flow in a radial flow convergent-divergent nozzle whose throat lies on the arc of a circle can create, in the neighborhood of the throat, a region capable of trapping and guiding light. Such a device, with a deflection angle of 90 degrees and a throat radius of 7.6 cm, was investigated. The working gas was nitrogen at supply pressures of 30-100 atm. The transmission characteristics of the device at light power densities up to 3 x 10(8) W/cm(2) were measured. No reduction in transmission attributable to high power densities was found up to levels of 3 x 10(8) W/cm(2) at the beam focus at input of the device, equivalent to an average level over the light guiding region of 10(7) W/cm(2) . The maximum measured transmission of the device at the maximum power density was 99.8 +/- 1.0%.