Chinese Optics Letters, Volume. 23, Issue 6, 061404(2025)

Dynamic coherence control of random lasers and its effect on speckle and edge sharpness of images

Zhihao Li1, Jianghao Li1, Yanyan Huo1, Yangjian Cai1,2、*, and Yuan Wan1、**
Author Affiliations
  • 1Shandong Provincial Engineering and Technical Center for Light Manipulation and Shandong Provincial Key Laboratory of Optics and Photonic Devices, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
  • 2Joint Research Center of Light Manipulation Science and Photonic Integrated Chip of East China Normal University and Shandong Normal University, East China Normal University, Shanghai 200241, China
  • show less
    Figures & Tables(6)
    Schematic diagram of the experimental setup. HWP, half-wave plate; POL, polarizer; NBS, neutral beam splitter; CL, cylindrical lens; DC, DC voltage source; L, convex lens; F, filter; FS, fiber spectrometer; DS, double slit plate; S, scatterer; M, mirror; AF, 1951 US Air Force resolution test chart; Ob, 20× microscope objective.
    Radiation characteristics of the electrical controllable random laser. (a) The emission spectrum of the random laser as a function of the pump energy. Inset: the random laser spectrum is captured at the pump energy of 4.35 µJ/pulse. (b) The peak intensity of the corresponding emission spectrum as a function of the pump energy. (c) The emission spectrum of the random laser as a function of the number density of the TiN nanoparticles. Inset: the peak intensity of the corresponding emission spectrum as a function of the number density of the TiN nanoparticles. (d) The emission spectrum of the random laser as a function of the applied voltage when the pump energy is 18.5 µJ/pulse. (e) The peak intensity of the emission spectrum as a function of the voltage. (f) Transmission spectrum intensities of the nematic liquid crystal at different voltages.
    Spatial coherence. (a) Spatial coherence of the Nd:YAG laser. (b)–(d) Spatial coherence of the random laser at different voltages when the pump energy is 18.4 µJ/pulse: (b) 0, (c) 4.5, and (d) 11 V. Top, the interference fringes. Down, the intensity distributions of interference fringes along the white dotted lines. (e) The variation curve of the random laser spatial coherence as a function of the applied voltage.
    Speckle. (a) Speckle pattern for the Nd:YAG laser. (b)–(d) Speckle patterns for the random laser at different voltages: (b) 0, (c) 4.5, and (d) 11 V. Top, speckle images captured by a CCD camera. Down, intensity distributions along the white dotted lines. The pump energy is 18.2 µJ/pulse. (e) The speckle contrast as a function of the applied voltage.
    (a) Image illuminated by the Nd:YAG laser. Inset: enlarged images. (b)–(d) Images illuminated by the random laser with different voltages from left to right are 0, 4.5, and 11 V. (e)–(h) The intensity obtained from the image along the white dashed line. (i)–(l) The intensity obtained from the inset image along the dashed line. Inset: enlarged images showing the details of the speckle in the same area. (m)–(p) The intensity obtained from the inset image along the dashed line. Inset: enlarged images showing the image edge in the same area.
    Values of the signal-to-noise ratio (SNR), speckle contrast (SC), and edge sharpness (ES) of the image as a function of the voltage.
    Tools

    Get Citation

    Copy Citation Text

    Zhihao Li, Jianghao Li, Yanyan Huo, Yangjian Cai, Yuan Wan, "Dynamic coherence control of random lasers and its effect on speckle and edge sharpness of images," Chin. Opt. Lett. 23, 061404 (2025)

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category: Lasers, Optical Amplifiers, and Laser Optics

    Received: Oct. 22, 2024

    Accepted: Dec. 31, 2024

    Published Online: May. 19, 2025

    The Author Email: Yangjian Cai (yangjian_cai@163.com), Yuan Wan (wanyuansdnu@163.com)

    DOI:10.3788/COL202523.061404

    CSTR:32184.14.COL202523.061404

    Topics