Guided Wave Fluorescence In Thin Film Er- Doped Barium Titanate
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Mat. Res. Soc. Symp. Proc. Vol. 486 01998 Materials Research Society
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Wavelength (nm) Figure 1.) a.) Transmission of a light emitting diode emission (FWHM-75 nm, central frequency -1.55 pm) through an 8.2 mm long 5 pm wide Er:BaTiO3 channel waveguide. The normalizing curve a is from an undoped BaTiO 3 waveguide grown under similar conditions. Curve c shows the transmission through the piece after a 1 hr. 02 anneal (labeled 1 hr oxygen anneal in the legend). Curve b shows the transmission through the piece after a subsequent 5 hr. 02 anneal. (monochromator resolution -1 nm).
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Wavelength (nm) Figure 1.) b.) Curve a is the transmission of the LED emission through the undoped waveguide. Curve b shows the transmission through the waveguide after a total of six hours of oxygen annealing at 700 °C in oxygen. Curve c shows the transmission through the same waveguide after a subsequent 2 hour arcnn annea].
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light emitting diode (LED, FWHM-75 nrm, X•ntai-l.55 mrn). The absorption at 1535 nrm was determined by comparing the throughput of the high power pump light to the throughput of the 1535 nm light at very low powers. Gain was measured with 1.465 Pm and 1.538 pin pump and signal diode lasers, respectively. The transmission of a broad band LED through the 8.2 mm long Er:BaTiO3 waveguide is shown in figures la and lb. For comparison the transmission of the LED emission through an undoped waveguide is also shown. Figure Ia shows the transmission of the LED emission through the waveguide after a 1 hr. oxygen anneal (at 700 TC) and also after an additional 5 hours of annealing in the oxygen atmosphere. The longer anneal time results in a reduction in absorption for wavelengths greater than -1545 nm, however, the absorption at 1535 nm is relatively unchanged. A peak resonant absorption of - -8.8 dB/cm at X,- 1.535 pm was measured, which corresponds to an Er atomic absorption cross section of -1.2 x 10-19 cm-2 at 1.535 pm (using a calculated light/film overlap -85 %). Figure lb shows the LED transmission through the same waveguide after a subsequent 2-hour argon anneal. The absorption in the waveguide is seen to increase. Table I shows the 1580 nm guided wave absorption as a function of anneal time and atmosphere. The absorption at 1580 rim was determined by comparing the transmission of the LED output through an undoped waveguide to that of the doped waveguide. The absorption at 1580 nm is seen to decrease when the sample is oxygen annealed and increase when the sample is argon annealed. The induced changes in absorption were repeatable. Since BaTiO3 is reduced during argon annealing these results suggest that oxygen vacancies play a role in the strong absorption at X - 1580 nm. Table 1.) Absorption of 1580 nm light as a function of annealing time and temperature. Anneal Atmosphere
Anneal Time
1580 nm Absorption (dB/cm)
Oxygen Oxygen Argon Oxygen Argon
1 hr.
- 7.0 -3.7 -6.8 -4.7 - 6.
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