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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 schematic illustration of our SPIDER setup.BS1, BS2: beam splitters; M1, M2: mirror; DL: temporal delay line; Stretcher: pulse stretcher; HW: achromatic half-wave plate; QW: achromatic quarter-wave plate; OAPM: 90° off-axis parabolic mirror; BBO: 42.3°-cut β-BBO crystal for sum-frequency conversion; FP: fused silica plate; SP: fiber spectrometer.
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f5: The schematic illustration of our SPIDER setup.BS1, BS2: beam splitters; M1, M2: mirror; DL: temporal delay line; Stretcher: pulse stretcher; HW: achromatic half-wave plate; QW: achromatic quarter-wave plate; OAPM: 90° off-axis parabolic mirror; BBO: 42.3°-cut β-BBO crystal for sum-frequency conversion; FP: fused silica plate; SP: fiber spectrometer.

Mentions: We implement our TSPS-SPIDER by the setup as shown in Fig. 5 which is a typical SPIDER except adding an achromatic quart-wave plate (QW) and a fused silica plate (FP) in one arm (A) of the MI. Here the QW is firstly aligned with its fast axis being parallel to the polarization of the double-passing laser beam, so the beam can get an additional π phase-shifting without change of its polarization by rotating the QW with 90°. The BS2, a 2 mm-thick broadband 50:50 beam splitter made of fused silica, is aligned so that its reflecting surface faces towards arm A. The FP is used to balance the total dispersion of the arm A with that of arm B, so our setup is qualified for few-cycle pulses. Our QW includes a 0.50 mm-thick MgF2 plate and a 0.61 mm-thick quartz plate, so we can figure out the required thickness of the FP shall be about 1.405 mm under Brewster angle incidence. With a dispersion-balanced MI, the SPIDER setup can be regarded as a glass plate with the dispersion of one of the two arms followed by the SPIDER setup but with a zero-thick BS2. Our pulse stretcher consists of a pair of 180° folding right-angle prisms (FRAP) made of SF57 glass which are displaced by face to face. This stretcher is very compact, easy to align, but can work with variable dispersion by shifting one of the prism as shown in Fig. 5 thereby changing the displacement between their apexes. By using the stretcher, the 800 nm laser pulses with a bandwidth of 26 nm can be stretched from 2.4 to 15 ps. The achromatic half-wave plate (HW) is used to rotate the polarization of the stretched pulse by 90° in order for the sum-frequency conversions between the chirped pulse and the test pulse replicas via type-II phase-matching. The spectrometer used to record the sum-frequent pulse pair is a fiber spectrometer (HR 4000, Ocean Optics) with a resolution of 0.05 nm.


Two-step phase-shifting SPIDER
The schematic illustration of our SPIDER setup.BS1, BS2: beam splitters; M1, M2: mirror; DL: temporal delay line; Stretcher: pulse stretcher; HW: achromatic half-wave plate; QW: achromatic quarter-wave plate; OAPM: 90° off-axis parabolic mirror; BBO: 42.3°-cut β-BBO crystal for sum-frequency conversion; FP: fused silica plate; SP: fiber spectrometer.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: The schematic illustration of our SPIDER setup.BS1, BS2: beam splitters; M1, M2: mirror; DL: temporal delay line; Stretcher: pulse stretcher; HW: achromatic half-wave plate; QW: achromatic quarter-wave plate; OAPM: 90° off-axis parabolic mirror; BBO: 42.3°-cut β-BBO crystal for sum-frequency conversion; FP: fused silica plate; SP: fiber spectrometer.
Mentions: We implement our TSPS-SPIDER by the setup as shown in Fig. 5 which is a typical SPIDER except adding an achromatic quart-wave plate (QW) and a fused silica plate (FP) in one arm (A) of the MI. Here the QW is firstly aligned with its fast axis being parallel to the polarization of the double-passing laser beam, so the beam can get an additional π phase-shifting without change of its polarization by rotating the QW with 90°. The BS2, a 2 mm-thick broadband 50:50 beam splitter made of fused silica, is aligned so that its reflecting surface faces towards arm A. The FP is used to balance the total dispersion of the arm A with that of arm B, so our setup is qualified for few-cycle pulses. Our QW includes a 0.50 mm-thick MgF2 plate and a 0.61 mm-thick quartz plate, so we can figure out the required thickness of the FP shall be about 1.405 mm under Brewster angle incidence. With a dispersion-balanced MI, the SPIDER setup can be regarded as a glass plate with the dispersion of one of the two arms followed by the SPIDER setup but with a zero-thick BS2. Our pulse stretcher consists of a pair of 180° folding right-angle prisms (FRAP) made of SF57 glass which are displaced by face to face. This stretcher is very compact, easy to align, but can work with variable dispersion by shifting one of the prism as shown in Fig. 5 thereby changing the displacement between their apexes. By using the stretcher, the 800 nm laser pulses with a bandwidth of 26 nm can be stretched from 2.4 to 15 ps. The achromatic half-wave plate (HW) is used to rotate the polarization of the stretched pulse by 90° in order for the sum-frequency conversions between the chirped pulse and the test pulse replicas via type-II phase-matching. The spectrometer used to record the sum-frequent pulse pair is a fiber spectrometer (HR 4000, Ocean Optics) with a resolution of 0.05 nm.

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.