P.C. Becker

Compression of optical pulses to six femtoseconds by using cubic phase compensation

We demonstrate that a combination of prisms and diffraction gratings can provide not only quadratic but also cubic phase compensation of ultrashort optical pulses. We obtain compressed pulses as short as 6 fsec.

Evolution of the vibronic absorption spectrum in a molecule following impulsive excitation with a 6 fs optical pulse

Abstract Using a 6 fs optical pulse we have impulsively excited the entire manifold of Franck-Condon-connected vibronic levels for the S 0 to S 1 transition in an organic dye in solution. Periodic perturbations to the absorption spectrum are observed as a consequence of the nuclear motion brought about by the coherent excitation of the manifold of vibrational levels.

Dynamics of spectral hole burning

A model calculation is presented that describes the features of spectral-hole burning measurements performed under conditions of femtosecond transient excitation and probing. Pump-induced changes in the spectrum of probe transmittance arise not only from changes in level population (hole burning), but also from the presence of pump polarization during the probe, and from perturbations of the decay of the probe polarization. These latter effects give rise to oscillating differential transmittance spectra when the (shorter) probe pulse arrives prior to the peak of the pump noise. Only when the probe pulse follows the bulk of the pump pulse does the level population effect dominate the spectrum, so that one can observe dynamic hole-burning effects without distortion. >

Femtosecond intervalley scattering in GaAs

We report the measurement of intervalley scattering rates for optically excited carriers in GaAs. The measurements were performed using optical pulses of 6 fs duration and an energy distribution centered at 2.0 eV. The average rates for Γ→X and Γ→L intervalley scattering were separately estimated by varying the sample temperature.

Concentration-dependent /sup 4/I/sub 13/2/ lifetimes in Er/sup 3+/-doped fibers and Er/sup 3+/-doped planar waveguides

We report on the concentration- and pump-dependent lifetimes of the spontaneous emission in Er/sup 3+/-doped fibers and Er/sup 3+/-doped waveguides. In addition, we measure the concentration dependence of the 550-nm fluorescence due to excited state absorption (ESA).<<ETX>>

1.54 μm room‐temperature luminescence of MeV erbium‐implanted silica glass

MeV erbium implantation doping of 10‐μm‐thick silica glass films on a Si substrate is studied with the aim of incorporating the rare‐earth dopant on an optically active site in the silica network. As‐implanted samples (3.5 MeV, 5×1015 Er ions/cm2) show a strong luminescent transition at a wavelength of 1.54 μm, even at room temperature, corresponding to an intra‐4f transition of Er3+. Thermal annealing at temperatures up to 900 °C increases the luminescence intensity by a factor of 2 to 3. For temperatures above 1000 °C the intensity decreases drastically as a result of Er precipitation. The lifetime of the excited state is in the order of 10 ms. Photoluminescence studies at 4.2 K are used to identify implantation‐induced damage.

Systems evaluation of an Er/sup 3+/-doped planar waveguide amplifier

We report the output saturation power, excess noise factor, and system performance of a highly concentrated Er/sup 3+/-doped planar optical waveguide amplifier. The performance data demonstrate the potential usefulness of planar optical waveguide amplifiers in system applications.<<ETX>>

Phase correction of femtosecond optical pulses using a combination of prisms and gratings

The performance of a combination of prisms and diffraction gratings as phase correctors is calculated numerically. Special attention is given to the regime where the pulse duration is 10 fsec or less.

Generation of tunable 9 femtosecond optical pulses in the near infrared

We report the generation of tunable femtosecond pulses in the 800–850 nm range. These pulses were obtained by generating a femtosecond continuum and selectively amplifying a portion of that continuum. The amplified femtosecond infrared pulses thus obtained were then compressed to a duration of 9 fs by a fiber followed by a grating and prism sequence.

Observation of multiple wavelength soliton collisions in optical systems with fiber amplifiers

Solitons of different wavelengths are found to exhibit substantial spectral and temporal changes when collisions are centered in erbium‐doped fiber amplifiers. By using two soliton pulse trains, with ∼70‐ps‐wide pulses, spectrally separated by 1.8 A, and 106 km of non‐dispersion‐shifted fiber, we observe a spectral and temporal shift of as much as 0.35 A and 55 ps, respectively, for each soliton. Both soliton wavelengths shift the same amount, but in opposite directions and remain undisturbed in terms of shape and amplitude after the collision. This shift may impose limitations on multiple wavelength soliton based communication systems utilizing fiber amplifiers.