| 研究概要 |
Four-wave mixing (FWM) in optical fibers is promising for wavelength conversion in optical networks due to its ultrafast response and high bit rate transmission. To further improve the performance of FWM-based wavelength conversion such as its bandwidth and conversion efficiency, the low nonlinearity of silica fibers should be improved by using novel highly nonlinear soft-glass fibers such as lead-silicate, bismuth-oxide, tellurite and chalcogenide fibers. In this work, a tellurite step-index fiber with large core is fabricated to keep the zero-dispersion wavelength (ZDW) of the fundamental mode close to that of the material dispersion which is located in the near-infrared region. By using a femtosecond pulsed laser pumped in the vicinity of the ZDW, it is expected to broaden and extend the bandwidth of the FWM-based wavelength conversion towards the near-infrared window for potential applications. When the pump wavelength was tuned from 1647 to 1795 nm, the signal was tuned from 1550 to 1434 nm, and the idler was generated from 1757 to 2400 nm. A 17.5 dB maximum signal gain at 1550 nm and +1.1 dB idler conversion efficiency at 1757 nm were obtained. When the pump wavelength was 1795 nm, the signal and generated idler wavelengths were 1434 and 2400 nm, respectively. To the best of our knowledge, this is the first time to demonstrate a FWM-based wavelength conversion performance whose wavelength spacing is ~966 nm (from 1434 to 2400 nm) in a tellurite step index optical fiber as short as 1 m.
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