Author Affiliations
1MOE Key Laboratory of Weak-Light Nonlinear Photonics, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300457, China2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Chinashow less
Fig. 1. (a) Schematic diagram of the designed slit-width-chirped random-phase grating. an (n=1,2,…,N) is the width of the nth slit, and N is the total slit number of the grating; ϕ(t) is a random phase changing with time among [0,2π), and d is the fixed period of the grating. (b) Schematic configuration for studying the coherence property of the light field transmitting through the chirped random-phase grating in the Fraunhofer zone, where L represents a lens for collecting the scattering light from the chirped random-phase gratings and CCD is the charge-coupled device camera for recording the intensity distribution on the focal plane of lens L. (c) Schematic diagram of indistinguishable two-photon paths.
Fig. 2. Schematic diagram of the experimental setup. λ/2, half-wave plate; L1, L2, L3, lenses; A1, A2, irises; BE, beam expander; P, polarizer; BS, 50∶50 beam splitter; CRPG, chirped random-phase grating; CCD, charge-coupled device camera. The straight arrows in the optical path indicate the propagating and scattering light. The upper-right inset shows the detailed structure of the chirped random-phase grating, which is composed of an N-slit black–white transmitting amplitude mask and an SLM, and they are placed as close as possible. The lower-left inset shows the object placed on the focal plane of L3 in the ghost imaging experiments.
Fig. 3. Experimental results for the super-bunched focusing effect with (a) slit-width-chirped random-phase gratings and (b) period-chirped random-phase gratings. The grating period in (a) was fixed at d=400 μm, and the chirped slit width {an} values are listed in Appendix B.1. In (b), the slit width was set to be a=100 μm, and the chirped grating grid lines {bk} are listed in Appendix B.2. The black solid curves, the blue dash-dotted curves, and the red dotted curves depict the results for N=4, 8, and 16, respectively.
Fig. 4. Experimental results for the super-bunched focusing effect through chirped random-phase gratings with N=50. (a) Slit-width-chirped random-phase grating with a fixed period d=200 μm, (b) period-chirped random-phase grating with a fixed slit width a=30 μm. The corresponding structure parameters can be found in Appendices B.3 and B.4, respectively.
Fig. 5. Normalized ghost image profiles with super-bunched focusing light fields for (a) the slit-width-chirped random-phase gratings and (b) the period-chirped random-phase gratings. The shaded parts represent the opaque areas of the double-slit mask. The blue dashed curves, the green dotted curves, the red dash-dotted curves, and the pink dash-dot-dotted curves depict the results with N=4, 8, 16, and 50, respectively. For comparison, the black solid curves show the case of a pseudo-thermal light field generated through a phase-only SLM.