• Photonics Research
  • Vol. 9, Issue 5, 05000839 (2021)
Yuchan Zhang1, Qilin Jiang1, Kaiqiang Cao1, Tianqi Chen1, Ke Cheng1, Shian Zhang1, Donghai Feng1, Tianqing Jia1、2、*, Zhenrong Sun1, and Jianrong Qiu3
Author Affiliations
  • 1State Key Laboratory of Precision Spectroscopy, School of Physics and Materials Science, East China Normal University, Shanghai 200062, China
  • 2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
  • 3State Key Laboratory of Optical Instrumentation, Zhejiang University, Hangzhou 310027, China
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    (a) Experimental setup used for processing LSFL on silicon with a temporally shaped femtosecond laser. (b) Periodic π-phase step modulation applied to the laser spectrum. (c) Temporal intensity profile of the shaped pulse of 16.2 ps with a modulation period of 4.5 cm−1.
    Fig. 1. (a) Experimental setup used for processing LSFL on silicon with a temporally shaped femtosecond laser. (b) Periodic π-phase step modulation applied to the laser spectrum. (c) Temporal intensity profile of the shaped pulse of 16.2 ps with a modulation period of 4.5  cm1.
    Schematic diagram of shaped pulse laser-induced regular and deep LSFL. The red area in the Si substrate presents the high temperature region when the sub-pulse reaches the surface.
    Fig. 2. Schematic diagram of shaped pulse laser-induced regular and deep LSFL. The red area in the Si substrate presents the high temperature region when the sub-pulse reaches the surface.
    (a)–(d) SEM images of LSFL fabricated by shaped pulse of 16.2 ps through laser direct writing in parallel lines. (e) SEM image of the cross section of the LSFL. (f) 2D-FFT image of (b). (g) Spectrum of the FFT along the x axis. The scale bar in (e) is 500 nm long. The dash arrow in (a) presents the laser polarization, and the solid arrow presents the scan direction.
    Fig. 3. (a)–(d) SEM images of LSFL fabricated by shaped pulse of 16.2 ps through laser direct writing in parallel lines. (e) SEM image of the cross section of the LSFL. (f) 2D-FFT image of (b). (g) Spectrum of the FFT along the x axis. The scale bar in (e) is 500 nm long. The dash arrow in (a) presents the laser polarization, and the solid arrow presents the scan direction.
    (a) Optical characterization measurement for testing the diffractive properties of large-area LSFL. The diffraction spectra from the LSFL fabricated (b) by shaped pulse of 16.2 ps and (c) by FTL pulse. The orderly multicolor diffraction pattern from the LSFL fabricated (d) by shaped pulse of 16.2 ps and (e) by FTL pulse.
    Fig. 4. (a) Optical characterization measurement for testing the diffractive properties of large-area LSFL. The diffraction spectra from the LSFL fabricated (b) by shaped pulse of 16.2 ps and (c) by FTL pulse. The orderly multicolor diffraction pattern from the LSFL fabricated (d) by shaped pulse of 16.2 ps and (e) by FTL pulse.
    Structural colors of “Chinese knot” pattern made up of LSFL fabricated by shaped pulse of 16.2 ps on Si surface. The white scale bars are 5 mm long.
    Fig. 5. Structural colors of “Chinese knot” pattern made up of LSFL fabricated by shaped pulse of 16.2 ps on Si surface. The white scale bars are 5 mm long.
    (a) At different scan velocity, the laser fluence windows for fabricating spaced (green), regular (orange), and partly damaged (blue) LSFLs by shaped pulse of 16.2 ps (the upper area) and by FTL pulse (the lower area). The SEM images (s1)–(s6) and (f1)–(f6) are the corresponding LSFLs of the marked points in (a). The dash arrow in (s1) presents the laser polarization, and the solid arrow presents the scan direction. The scale bars have a length of 3 μm.
    Fig. 6. (a) At different scan velocity, the laser fluence windows for fabricating spaced (green), regular (orange), and partly damaged (blue) LSFLs by shaped pulse of 16.2 ps (the upper area) and by FTL pulse (the lower area). The SEM images (s1)–(s6) and (f1)–(f6) are the corresponding LSFLs of the marked points in (a). The dash arrow in (s1) presents the laser polarization, and the solid arrow presents the scan direction. The scale bars have a length of 3 μm.
    Confocal microscopy images of the regular LSFL fabricated by (a) FTL pulse (F=0.43 J/cm2) and (b) shaped pulse of 16.2 ps (F=0.69 J/cm2). The scan velocity is 5.0 mm/s. (c) and (d) 2D plots of the cross sections along the yellow arrows in (a) and (b), respectively. (e) Average depth of the LSFL along the cross section perpendicular to the ablation trace.
    Fig. 7. Confocal microscopy images of the regular LSFL fabricated by (a) FTL pulse (F=0.43  J/cm2) and (b) shaped pulse of 16.2 ps (F=0.69  J/cm2). The scan velocity is 5.0 mm/s. (c) and (d) 2D plots of the cross sections along the yellow arrows in (a) and (b), respectively. (e) Average depth of the LSFL along the cross section perpendicular to the ablation trace.
    SEM images of the surface nanostructures fabricated by FTL pulse at different scanning velocities of (a) 16 mm/s, (b) 14 mm/s, (c) 10 mm/s, and (d) 8 mm/s. The laser fluence was fixed at 0.54 J/cm2. The dashed arrow presents the laser polarization, and the solid arrow presents the scanning direction. The scale bars are all 5 μm in length.
    Fig. 8. SEM images of the surface nanostructures fabricated by FTL pulse at different scanning velocities of (a) 16 mm/s, (b) 14 mm/s, (c) 10 mm/s, and (d) 8 mm/s. The laser fluence was fixed at 0.54  J/cm2. The dashed arrow presents the laser polarization, and the solid arrow presents the scanning direction. The scale bars are all 5 μm in length.
    SEM images of the surface nanostructures fabricated by shape pulse of 16.2 ps at different scanning velocities of (a) 17 mm/s, (b) 15 mm/s, (c) 13 mm/s, and (d) 11 mm/s. The laser fluence was fixed at 1.13 J/cm2. The dashed arrow presents the laser polarization, and the solid arrow presents the scanning direction. The scale bars are all 5 μm long.
    Fig. 9. SEM images of the surface nanostructures fabricated by shape pulse of 16.2 ps at different scanning velocities of (a) 17 mm/s, (b) 15 mm/s, (c) 13 mm/s, and (d) 11 mm/s. The laser fluence was fixed at 1.13  J/cm2. The dashed arrow presents the laser polarization, and the solid arrow presents the scanning direction. The scale bars are all 5 μm long.
    Confocal optical images of LSFL fabricated by shaped pulse of (a) 16.2 ps, 0.65 J/cm2; (b) 4.1 ps, 0.44 J/cm2; (c) 1.0 ps, 0.43 J/cm2; and (d) 0.25 ps, 0.42 J/cm2. The scan velocity was fixed as 5 mm/s. (e) The period and depth of the LSFLs for different intervals of sub-pulse.
    Fig. 10. Confocal optical images of LSFL fabricated by shaped pulse of (a) 16.2 ps, 0.65  J/cm2; (b) 4.1 ps, 0.44  J/cm2; (c) 1.0 ps, 0.43  J/cm2; and (d) 0.25 ps, 0.42  J/cm2. The scan velocity was fixed as 5 mm/s. (e) The period and depth of the LSFLs for different intervals of sub-pulse.
    Evolution of (a) the carrier density, (b) the carrier temperature, (c) the lattice temperature, and (d) the real part of the dielectric constant on the Si surface irradiated with shaped pulse of 16.2 ps.
    Fig. 11. Evolution of (a) the carrier density, (b) the carrier temperature, (c) the lattice temperature, and (d) the real part of the dielectric constant on the Si surface irradiated with shaped pulse of 16.2 ps.
    LSFLs2s3s5s6
    DSOA3.7°6.7°2.5°5.8°
    LSFLf2f3f5f6
    DSOA4.0°11.5°17.5°22.5°
    Table 1. DSOA of the Regular Ripples and Partly Damaged Ripples in Fig. 6
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    Yuchan Zhang, Qilin Jiang, Kaiqiang Cao, Tianqi Chen, Ke Cheng, Shian Zhang, Donghai Feng, Tianqing Jia, Zhenrong Sun, Jianrong Qiu. Extremely regular periodic surface structures in a large area efficiently induced on silicon by temporally shaped femtosecond laser[J]. Photonics Research, 2021, 9(5): 05000839
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    Category: Ultrafast Optics
    Received: Jan. 11, 2021
    Accepted: Mar. 4, 2021
    Published Online: May. 7, 2021
    The Author Email: Tianqing Jia (tqjia@phy.ecnu.edu.cn)