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.
The vacuum ultraviolet absorption spectrum to 1200 Å has been obtained for the products from the evaporation of graphite at 2700 °C, trapped in argon at 8 K. Based on correlations with the 1Πu–X1Σ+g transition of C3 in the near ultraviolet, the results of 13C substitution, and other observational evidence, it is proposed that a band system originating at 1890 Å be assigned to the 1Σ+u–X1Σ+g transition of C3. Vibrational analysis yields ν1′≂1080, ν2′≂300, and ν3′≂780 cm−1 for the 1Σ+u state.
We show that the coupling efficiency from a laser diode (LD) to an optical fiber through a ball lens can be calculated accurately using the exact solution to Maxwell's equations for the scattering of a beam from a dielectric sphere. Our calculated results agree closely with coupling measurements from an asymmetric LD for two different ball lenses.
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