NEAR-INFRARED FIBER RAMAN OSCILLATOR TUNABLE FROM 1.07 TO 1.32-MU-M

We report a near-infrared fiber Raman oscillator in the 1.1-1.3-μm spectral region. The Raman medium is an 800-m-long 6.3-μm-core-diam single-mode fiber with a loss less than 2 dB/km near 1.2 μm and less than 4 dB/km over the 1-1.32-μm spectral range. The oscillator is synchronously pumped by a cw mode-locked Nd: YAG laser. With four separate resonator mirrors, four orders of Stokes oscillations, peaked near 1.12, 1.18, 1.24, and 1.31 μm, are obtained. With simultaneous tuning of all the four Stokes wavelengths we have achieved continuously tunable oscillation over 250 nm (1.07-1.32 μm), the first such broadly tunable laser in this spectral range.