| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
We constituted two types of optical fiber ring lasers using Er-doped optical fibers (a low and a high Er-doping concentration) , which were pumped 980nm or 1480nm semiconductor laser diodes via a WDM optical fiber coupler, and measured the characteristics of the laser outputs, the lasing wavelengths, and the wavelength tuning. The laser outputs were obtained through an optical fiber coupler of which the coupling ratio was variable. In case of the low concentration, the Er-doped fiber length was 23.0m, the loop length 30.8m, and the concentration-length product 115.kppmm. When pumping power was 35mW and 56.7% coupling ratio, the maximum lasing output was 2.4mW.When the coupling ratio was 68.0%, the maximum slope efficiency was 8.9%. And the lasing spectral linewidth was measured as 3kHz using a 80km-ring version delayd self heterodyne method. In the hign concentration having the same concentration-length product of the low case, the maximum lasing output was 2.1mW at 35mW pumping and 77.3% coupling, the maximum slope efficiency was 9.1% at 88.8% coupling, and the lasing spectral linewidth was 5kHz. We also investigated an injection-locked fiber ring laser which was optically injected from a semiconducter laser diode. Resultingly, it was found that an extremely narrow linewidth of the master laser was needed for stable locked oscillations. In addition, we studied on use of out ring fiber confirulation as a ring fiber filter which acted as a pumping-power-controlable bandpass filter.
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