Picosecond pump-probe interferometric measurement of optical nonlinearity in semiconductor-doped fibers.

Refractive and absorptive optical nonlinearity can be distinguished using a pump-probe interferometric technique with picosecond time resolution. The method is applied to both resonant and nonresonant nonlinearities in optical fibers and reveals marked differences between the relaxation behavior of the refractive and absorptive nonlinearity in certain cases. A monomode fiber doped with CdS(x)Se(1-x) semiconductor nanocrystals exhibits a large optically induced phase shift with ~10-psec relaxation time, which is many orders faster than the relaxation of the absorptive nonlinearity under identical conditions.

Cascade Raman soliton fiber ring laser.

Pulses as short as 200 fsec at 1.5 microm and 230 fsec at 1.6 microm have been generated through a cascade Raman, solitonlike process in a fiber ring oscillator. A dispersion-shifted (lambda(0) = 1.46 microm) single-mode fiber was used as the gain medium, which was synchronously pumped by a cw mode-locked Nd:YAG laser operated at 1.32 microm.

A Nd(3+)-doped cw fiber laser using all-fiber reflectors.

We demonstrate a novel all-fiber resonant optical cavity which uses two-fiber reflectors, each formed by a single loop of fiber between the output ports of a fiber directional coupler. The reflectivities of the fiber mirrors are each determined by the coupling ratio and the insertion loss of the fused couplers. When the cavity is formed in this way using a continuous length of Nd(3+)-doped fiber and pumped using a GaAs laser diode, lasing occurs at a wavelength of 1064 nm. Both theoretical and practical descriptions of the device are given.