A new high-resolution femtosecond pulse shaper

Generation of Tunable THz Pulses

“…The pulse shaper consists in a half-zero-dispersion line made of a 600 g/mm grating and a f = 600 mm cylindrical mirror that spatially disperses and focuses all the spectral components of the pulse in the Fourier plane where a programmable single liquid crystal spatial light modulator (LC SLM) with 640 pixels, manufactured by Jenoptik AG, acts as a spectral filter [22,23,33,42]. A plane mirror positioned just after the SLM folds the line to perform an inverse Fourier transform and reassemble all the spectral components of the shaped pulse.…”

“…Now, we will see that the pixelated nature of the LC SLM imposes upper limits to T rep and Δτ. Indeed, to be correctly sampled by the modulator's pixels, and thus avoid temporal aliasing, the phase modulation must satisfy the Nyquist's criterion: the increase of phase between two adjacent pixels of the SLM must not exceed π [22,33,42]. For the sinusoidal and triangular phase modulations considered separately, this criterion, applied to our setup, leads respectively to T rep ≤ 4p s( i.e.…”

“…(d) cross-correlation of the NIR pulse pair, (e) associated THz waveform and (f) corresponding spectrum (taken from [37]). [33]. Second, the pixels, and consequently the gaps, of the LC SLM are not sharply defined, leading to some smoothing of the pixelated phase.…”

Four-user, 2.5-Gb/s, spectrally coded OCDMA system demonstration using low-power nonlinear processing

“…In addition, substantially longer code lengths would require LCMs (or other modulator array technologies) with more than 128 pixels. LCM devices with 512 [53] and 640 pixels [54] have been previously demonstrated for pulse shaping, and 640-element devices are now commercially available. 4) Actively mode-locked fiber lasers are relatively complicated compared with traditional continuous-wave semiconductor lasers used in WDM systems.…”

Shaping and characterization of tunable UV ultrashort pulses

“…Traditional methods for femtosecond pulse shaping are based on a Liquid Crystal Device (LCD) or Acousto-Optic Modulator (AOM) placed in the Fourier plane of a grating based zero dispersion 4f configuration [8][9][10]. The different wavelengths are spatially separated and can then be addressed individually.…”