A. Dubietis

A. Dubietis coauthored the 1992 paper introducing chirped and stretched pulse parametric amplification in beta barium borate with G. Jonušauskas and A. Piskarskas. Its publisher Abstract reports compressed pulses of $70\mathrm{fs}$ and approximately $0.9\mathrm{GW}$ output power.^[ref]

The approach connects optical parametric amplifier with the central logic of chirped pulse amplification: amplify a temporally stretched signal, then compensate its spectral phase to recover a short optical pulse. The amplified optical bandwidth matters because a narrow spectrum cannot support an arbitrarily short pulse, even with ideal compression.

For an original Gaussian pulse example, an intensity full width at half maximum $\Delta t$ and ordinary-frequency intensity width $\Delta \nu$ satisfy $\Delta t\Delta \nu =2\ln 2/\pi \approx 0.441$ for a transform-limited pulse. Thus a Gaussian spectrum of width $10\mathrm{THz}$ supports a transform-limited intensity duration of about $44.1\mathrm{fs}$. A measured duration of $100\mathrm{fs}$ with that same spectrum would have time-bandwidth product one, exceeding the transform-limited value. Residual spectral phase can account for such broadening, though the product alone does not uniquely reconstruct that phase. The stipulated bandwidth and durations are illustrative, not additional experimental data from the paper.