A. S. L. Gomes

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.

An experimental study of the primary parameters that determine the temporal compression of CW Nd:YAG laser pulses

Abstract An experimental study of temporally compressed CW Nd:YAG laser pulses using an optical fibre and diffraction grating pair technique has been carried out. The relevant experimental parameters have been varied so that a better insight into the physical processes could be gained and to enable some comparisons to be made with theory. Under optimum conditions an overall 47 × pulsewidth compression and 10 × enhancement in peak power have been achieved. Changes in fibre length, peak power and grating separation gave rise to outputs which showed good qualitative agreement with theoretical predictions.

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.

Characterisation of the output from a Q-switched/mode-locked cw Nd:YAG laser

Abstract Both single-shot and repetitively-operating streak cameras have been used for direct studies of the optical pulses produced by a simultaneously Q-switched and mode-locked cw Nd:YAG laser. Without prelase the mode-locked pulses are observed to be merely highly structured noise-bursts having durations of a few hundred picoseconds while with prelase, short (∼100 ps) stable pulses can be obtained at Q-switch repetition rates in excess of 1 kHz. These pulses are compared to those obtainable from the mode-locked laser without Q-switching.

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.

Optical and structural investigation of Nd3+ in silica-based fibres

Le systeme a la composition suivante: 94,5 SiO 2 -5,0 GeO 2 -0,5 P 2 O 5 . Les proprietes du titre sont etudiees par spectrometrie de fluorescence et par microscopie electronique a transmission analytique. Il se forme des clusters lorsque la concentration en Nd(III) est au-dessus de 10 3 ppm

Spectral and temporal study of picosecond-pulse propagation in a single-mode optical fibre

The power-dependent pulsewidth variations for input 85 ps pulses from a cw mode-locked Nd: YAG laser propagating through 125 m of single-mode optical fibre have been examined using a Synchroscan streak camera. Simultaneous spectral and temporal measurements provide information as to the optimum parameters for pulse compression in fibres.

Generation of subpicosecond pulses from a continuous-wave mode-locked Nd:YAG laser using a two-stage optical compression technique

By using a two-stage optical-fiber grating pair pulse-compression technique, 1.06-microm pulses as short as 0.7 psec have been obtained from an actively mode-locked cw Nd:YAG laser. This represents an overall pulse-compression ratio of 113.

Picosecond stimulated Raman generation, pump pulse fragmentation, and fragment compression in single-mode optical fibers

Pump pulse depletion has been examined for high peak power (∼ 100 kW) 90 ps pulses from a Q -switched and mode-locked Nd:YAG laser in 4 m of single-mode optical fiber. Fragmentation of the fundamental and low Stokes Raman orders has been observed for this cascading process. Pulse compression using an interferometric technique has been carried out, obtaining compression ratios of up to times five, on these fragments which exhibited a negative frequency chirp.

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.