Gouy-phase effects in the frequency combs of an optical parametric oscillator

Four-Dimensional Micro/Nanorobots via Laser Photochemical Synthesis towards the Molecular Scale

“…The literature review [ 22 , 25 , 33 , 34 , 35 , 36 , 37 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] also showcases the development of opto-mechatronics. The laser direct-writing setup adopts an orthodox “2 + 1” configuration, 2D scanning galvanometer/micromirror [ 73 ] plus 1D translation stage, advanced 3D galvanometer [ 74 ] with focus-adjusting ability, or inserting spatial phase modulators to form a “2 + 1” configuration.…”

“…In Figure 5 a 0 , it can be seen that the volume of the laser focus (known as “voxel”) directly affects the scanned nanowires; the photon polymerization reaction happens only inside the “voxel”. Previous investigations [ 18 , 62 , 63 , 64 , 65 , 66 , 67 , 68 , 69 , 70 ] conclude that the voxel shape focused by a Gauss laser beam is an eclipse at the nanoscale and that the volume of formed nanowires (its height and linewidth) depends on the laser voxel during scanning. Accordingly, the spatial resolution of the laser-scanning-induced nanowires, patterns, and structures is determined by the specific volume of the laser voxel.…”

“…The beginning is the coherent laser source; previous researches tell us that the nonlinear laser crystals (neodymium-doped yttrium aluminum garnet or yttrium aluminate, titanium-doped sapphire, potassium dihydrogen phosphate, and so on) work with advanced modulation techniques to irradiate laser beams covering ultraviolet-to-infrared wavelengths. Optical parametric oscillators [62] hold the responsibility to tune light wavelengths based on the nonlinear four-wave mixing effect [63], the wavelength-tuning is realized by physically changing the angle between the incident pump light and the laser crystal axis [64]. To fabricate delicate 4D shape-reconfigurable micro/nanostructures using these lasers, a digital optical platform (Figure 3) consisting of the above-discussed light sources and modulation setup is required.…”

Generalized Orbital Angular Momentum Symmetry in Parametric Amplification

“…The nonlinear coupling between different transverse modes is subject to conditions imposed by the spatial overlap between them, giving rise to selection rules that limit the modes allowed in the interaction [20][21][22][23]. When the process is intensified inside an optical resonator, cavity conditions also dictate which modes can survive the loss-gain balance, which can affect both the transverse [24][25][26] and longitudinal [27] mode structure. These effects determine whether OAM can be exchanged between the interacting modes [28][29][30][31].…”