Fig. 1. Schematic of the linear and nonlinear diffraction system of the white laser beam shining microstructural nonlinear grating. (a) Experimental setup of the white laser beam shining PPLN thin plate with a shallow grating of a depth of only 67 nm. (b) Photograph of the naked-eye white light spot from four different pump light sources (from left to right, ordinary halogen lamp, NKT white laser, white laser produced by fused silica module, and white laser produced by cascaded silica-CPPLN module). (c) Microscopic image of a weak grating surface of the PPLN sample.

Fig. 2. Photograph of linear diffraction dispersed via the (a) PPLN nonlinear grating and (b) gold-plated reflective grating (1200 lines/mm). (c) The output visible-near infrared (Vis-NIR) spectrum of an ordinary halogen lamp (Thorlabs SLS201L). Photograph of linear diffraction of NKT white laser spot dispersed via the (d) PPLN nonlinear grating and (e) gold-plated reflective grating (1200 lines/mm). (f) The output Vis-NIR spectrum of the NKT white laser (NKT Photonics, SuperK EXTREME EXW-12).

Fig. 3. (a) Photograph of linear and nonlinear diffraction of the fused silica white laser spot at 1.72 W dispersed via the PPLN nonlinear grating. Locally enlarged images of (b) LOD and (c) NCR patterns positioned to the left of the center point, in which the exposure of (c) is increased by a factor of 10 compared to (a) and (b). (d) Photograph of linear diffraction diffracted by a regular gold-plated reflective grating (1200 lines/mm). (e) The output ultraviolet-visible-near infrared (UV-Vis-NIR) spectrum of the fused silica white laser at 1.72 W.

Fig. 4. (a) Photograph of linear and nonlinear diffraction of the fused silica white laser spot at 0.8 W dispersed via the PPLN nonlinear grating. Locally enlarged images of (b) LOD and (c) NCR patterns positioned to the left of the center point, in which the exposure of (c) is increased by a factor of 10 compared to (a) and (b). (d) Photograph of linear diffraction diffracted by a regular Au-plated reflective grating (1200 lines/mm). (e)–(h) NCR patterns corresponding to input powers ranging from 0.5 to 0.12 W, respectively.

Fig. 5. (a) Photograph of linear and nonlinear diffraction of the CPPLN white laser spot at 0.82 W dispersed via the PPLN nonlinear grating. (b) Locally enlarged image of the LOD pattern positioned to the left of the center point. (c) Photograph of linear diffraction diffracted by a regular Au-plated reflective grating (1200 lines/mm). (d) The output UV-Vis-IR spectrum of the CPPLN white laser.