Sub-5-fs Pulse Compression of Laser Output Using Photonic Crystal Fiber with Short Zero-Dispersion Wavelength

Abstract

Output pulses from a photonic crystal fiber (PCF) with a zero-dispersion wavelength (ZDW: 853 nm) were compressed to 5.8 fs by feedback spectral-phase compensation. Furthermore, for another PCF with a shorter ZDW (744 nm), whose output spectral-phase measurement and pulse compression are generally thought to be difficult because of coherence degradation between pulses, we measured successfully their phases in the entire spectral region (480 to 1000 nm) by a suitable selection of input pulse and fiber parameters. The pulse compression experiment using an improved feedback system showed that in the short-wavelength region, pulses can be compressed to 4.9 fs, whereas in the entire spectral region, pulses cannot be compressed. This is because the visibility of the spectral interferogram in the spectral-phase interferometry for direct electric-field reconstruction (SPIDER) signal in the longer-wavelength region corresponding to the phase-sensitive soliton-breaking-up region is degraded by large phase modulation using a spatial light modulator.

Automatic Phase Compensation for Extremely Short Optical-Pulse Generation Using Wavelet Transform

“…Fig. 1 is one example of results after the step 1), which was calculated from the M-SPIDER signal measured for the PCF output [3], [4]. Fig.…”

“…In (1), in general, it is possible to separate dc and ac components by choosing large for an optical pulse whose intensity spectrum is clear and not ultrabroad [13]. However, it becomes difficult to separate those components when the optical pulse spectrum has a bandwidth as ultrabroad as that of nearly one octave and is complicated because 0018-9197/$25.00 © 2007 IEEE ) and that of one of its replica spectra (dotted curve) which were measured for the PCF output [3], [4]. It is difficult to set apart dc and +ac components.…”

“…The experimental setup was similar to our previously reported one [3], [4] except for the two following points. First, an original computer program was added for the phase analysis by the WT method enabling the reconstruction automatically.…”

“…4(a)] and the structured intensity spectrum (600 to 1010 nm) [ Fig. 4(a)] which had been measured in [4] with parameters of rad THz and fs. From the , the complicated spectral phase was reconstructed by the WT method with a good reproducibility but without any manual decision [ Fig.…”

“…Moreover, it has been shown that the technique is useful for pulse compression using a photonic crystal fiber (PCF) [3], [4] and for further pulse compression (e.g., 2.6 fs, 1.3 cycles) based on induced phase modulation [5]. This phase-compensation technique with a bandwidth exceeding the octave consists of the combination of a phase manipulator with a spatial light modulator (SLM) [6], a phase characterizer using a modified spectral phase interferometry for direct electric-field reconstruction (M-SPIDER) [7], and computers for phase analysis and SLM control.…”