A.S. Gouveia-Neto

Generation of 33-fsec pulses at 1.32 μm through a high-order soliton effect in a single-mode optical fiber

Pulse shortening by a factor of 2700x at 1.32 microm has been realized by means of a two-stage pulse compression. In the first stage, 90-psec pulses from a cw mode-locked Nd:YAG laser were compressed to ~1.5 psec by using a standard fiber-grating-pair configuration. Subsequent propagation of these pulses through ~20 m of single-mode optical fiber with a minimum dispersion at 1.27 microm led to a final pulse width of 33 fsec. This represents the shortest reported pulse generated at 1.32 microm by using the technique described above as well as the largest overall compression factor using optical fibers yet reported.

Subpicosecond-pulse generation through cross-phase-modulation-induced modulational instability in optical fibers

We report subpicosecond-pulse generation at 1.319 microm in a single-mode optical fiber by modulational instability induced through cross-phase modulation by 1.06-microm pulses propagating in the normal dispersion regime. Pulse-repetition rates approaching 300 GHz were achieved.

High-efficiency single-pass solitonlike compression of raman radiation in an optical fiber around 1.4 μm

Highly efficient conversion (as great as 60%) into the broad first Stokes Raman band around 1.4 μm of the 90-psec pump pulses from a cw mode-locked Nd:YAG laser at 1.32 μm has permitted, through a solitonlike compression mechanism in a single span of standard (λ0 = 1.3 μm) single-mode optical fiber, the generation of highly stable pulses of ∼100 fsec, with average powers of ∼30 mW in the solitary waves, which depend on fiber length and pump power.

Optical fibre-grating pulse compressors

This article reviews the current state-of-the-art of optical pulse compressors based on the optical fibre-grating pair. As this technique has become a standard laboratory procedure providing pulses with duration shorter than those directly generated from mode-locked lasers, we review the basic mechanism of the method, the role played by additional non-linear effects (such as stimulated Raman scattering), describe the current results, with emphasis to our own work, and point out the limitations of the technique.

Raman amplification of modulational instability and solitary-wave formation

The effect of synchrohous Raman gain in a single-mode fiber on a weak signal exhibiting modulational instability is shown spectrally and temporally to give rise to the rapid development of a single ultrashort solitary wave and a lowlevel dispersive pedestal.

Solitons in the region of the minimum group-velocity dispersion of single-mode optical fibers

Pulses launched with their central wavelength in the region of the minimum-dispersion wavelength of a single-mode optical fiber exhibit a distinct spectral splitting due to the nonlinearity. As a solitary wave evolves, the corresponding central wavelength of this component frequency downshifts while the dispersive wave is upshifted, in qualitative agreement with theoretical prediction.

Suppression and manipulation of the soliton self-frequency shift

Direct experimental evidence is presented that shows that in the presence of bandwidth-limited amplification, specifically, stimulated Raman scattering in a single-mode silica fiber, the self-frequency-shifting effect exhibited by solitons can be effectively suppressed.

Optical pulse narrowing by the spectral windowing of self-phase modulated picosecond pulses

Abstract An extra-cavity pulse narrowing technique is demonstrated in which a frequency-swept optical pulse is compressed by the application of a spectral window. The pulses from a cw mode-locked Nd:YAG laser were passed through an optical fibre in a regime where self-phase modulation was the dominant nonlinear mechanism, and group velocity dispersion and stimulated Raman scattering were negligible. A 3-fold compression ratio was obtained, in good agreement with theoritical predictions.

Soliton reconstruction through synchronous amplification

When pulses are launched with insufficient energy to create a soliton, they broaden as they propagate in optical fibers. We show that by synchronous Raman amplification this process can be reversed. Also, we show that it is not necessary to work in the limit of small gain. These results are in agreement with a theory of pulse generation and compression, which is discussed.

Spectral and temporal study of the evolution from modulational instability to solitary wave

Abstract Solitary waves with durations of 100–200 fs, but exhibiting significant dispersive pedestal components have been shown to evolve through preferential Raman amplification of modulational instability components generated through the passage of 100 ps pump pulses in the anomalously dispersive regime of a single mode opticll fibre.