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Two-step phase-shifting SPIDER

View Article: PubMed Central - PubMed

ABSTRACT

Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths.

No MeSH data available.


The recorded spectral interferogram I1 (inset) and the /D(t) − D′(t)/ (black line) and /D(t)/ (blue line) when τ = 0.45 ps (a), and the reconstructed temporal intensity and phase profiles by TSPS-SPIDER (b).
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f3: The recorded spectral interferogram I1 (inset) and the /D(t) − D′(t)/ (black line) and /D(t)/ (blue line) when τ = 0.45 ps (a), and the reconstructed temporal intensity and phase profiles by TSPS-SPIDER (b).

Mentions: Figure 2 predicts that the TSPS-SPIDER has obvious advantage over the traditional SPIDER in characterizing the ultrashort pulses with complicated spectral structures, where the fine spectral amplitude modulation requires the small time delay τ between the test pulse replicas. In order to generate the test pulses with complicated spectral structures, a 2.5 mm-thick CaF2 crystal is used as Kerr medium. The spectral interferogram is shown in the inset of Fig. 3(a). The complicated spectral structures usually result in complicated temporal structure, so after Fourier-transform, as shown in Fig. 3(a) where τ = 0.45 ps, both the dc and the ac have complicated temporal structures: multi-peaks and long pre/post backgrounds, which leads to the strong overlap with each other. Even so, the black line in Fig. 3(a) shows our TSPS-SPIDER has got a perfect removal of the dc, so we are still able to recover the spectral/temporal phases and intensities of the test pulses. Figure 3(b) uses dashed line for the temporal phase and solid line for intensity profile by our TSPS-SPIDER, which agrees with our numerical simulation very well. One can see that the self-phase modulation by using the Kerr medium results in the test pulse with complicated temporal intensity and phase profiles.


Two-step phase-shifting SPIDER
The recorded spectral interferogram I1 (inset) and the /D(t) − D′(t)/ (black line) and /D(t)/ (blue line) when τ = 0.45 ps (a), and the reconstructed temporal intensity and phase profiles by TSPS-SPIDER (b).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036035&req=5

f3: The recorded spectral interferogram I1 (inset) and the /D(t) − D′(t)/ (black line) and /D(t)/ (blue line) when τ = 0.45 ps (a), and the reconstructed temporal intensity and phase profiles by TSPS-SPIDER (b).
Mentions: Figure 2 predicts that the TSPS-SPIDER has obvious advantage over the traditional SPIDER in characterizing the ultrashort pulses with complicated spectral structures, where the fine spectral amplitude modulation requires the small time delay τ between the test pulse replicas. In order to generate the test pulses with complicated spectral structures, a 2.5 mm-thick CaF2 crystal is used as Kerr medium. The spectral interferogram is shown in the inset of Fig. 3(a). The complicated spectral structures usually result in complicated temporal structure, so after Fourier-transform, as shown in Fig. 3(a) where τ = 0.45 ps, both the dc and the ac have complicated temporal structures: multi-peaks and long pre/post backgrounds, which leads to the strong overlap with each other. Even so, the black line in Fig. 3(a) shows our TSPS-SPIDER has got a perfect removal of the dc, so we are still able to recover the spectral/temporal phases and intensities of the test pulses. Figure 3(b) uses dashed line for the temporal phase and solid line for intensity profile by our TSPS-SPIDER, which agrees with our numerical simulation very well. One can see that the self-phase modulation by using the Kerr medium results in the test pulse with complicated temporal intensity and phase profiles.

View Article: PubMed Central - PubMed

ABSTRACT

Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths.

No MeSH data available.