Pulse trains produced by phase-modulation of ultrashort optical pulses: tailoring and characterization

Abstract

In this paper, creation of pulse doublets and pulse trains by spectral phase modulation of ultrashort optical pulses is investigated. Pulse doublets with specific features are generated through step-like and triangular spectral phase modulation, whereas sequences of pulses with controllable delay and amplitude are produced via sinusoidal phase modulations. A temporal analysis of this type of tailored pulses is exposed and a complete characterization with the SPIDER technique (Spectral Phase Interferometry for Direct Electric-field Reconstruction) is presented.

Generation of Tunable THz Pulses

“…When a sinusoidal phase φ(ω) is applied to this pulse, it results in a pulse train with a temporal dependence of the electric field given by [29]:…”

“…So, by playing on the modulation strength a one can control, to some extend, the weight of the different pulses of the train. More precisely, the evolution of |J m (a)| is the following [29]: except for |J 0 |, it increases when a is varied from 1.25 to 2.65, leading to an enhancement of the number of pulses in the train. Hence, increasing a will lengthen the THz pulse duration and lead to a narrower spectrum, this regardless of the repetition rate F rep .…”

“…Unfortunately, their amplitude cannot be modified easily without affecting the amplitude of the other peaks. Indeed, as shown in reference [29], it is impossible to produce pulse trains with more than three pulses of equal amplitude with a simple sinusoidal phase. On the other hand, one can solve this problem by adding higher harmonic orders to the applied phase modulation, i.e.…”

Coherent control in the continuum: autoionization of Xe

“…In the particular case when ω n = ω 0 , an explicit Fourier transform has been found [6] and the temporal electric field has the following form,…”

“…In principle, such spectral phase and amplitude filtering techniques can produce almost any arbitrary pulse shape. Recently Renard et al [6] demonstrated that substantial control over the pulse shape can be achieved by shaping of the phase only.…”