An upconversion laser operating simultaneously at visible wavelengths of 520 and 490 nm under infrared semiconductor pumping is demonstrated. The Pr3+/Yb3+doped ZBLAN fluorozirconate fiber laser yielded 1.4 mW total power at green and blue wavelengths with approximately 350 mW of incident pump light at a wavelength of 856 nm. Threshold launched powers of 55 and 85 mW were obtained for the wavelengths of 520 and 490 nm, respectively.
We demonstrate blue laser emission from a direct semiconductor laser-diode-pumped Pr(3+)-doped upconversion fiber laser. This laser produced more than 1 mW of power at a wavelength of 492 nm from pump lasers operating at 830 and 1020 nm.
Plasma etching is a main stream technology in integrated circuit fabrication. The general trend towards fine linewidths and decreasing thickness of underlying layers (etch stops) results in an increasing dependence on highly controlled plasma etch processes. Such tight control requires in situ process monitoring, particularly, for determination of the etch endpoint. This paper reviews the various methods for endpoint detection. A novel application of interferometric principles for very precise etch endpoint determination in high density circuits is described. A comparison of several methods used simultaneously in a plasma planarization process is presented. The etch endpoint can also be determined by monitoring the pressure change in the chamber upon completion of the etch. An application of this method to dielectric etching is demonstrated.
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