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Lasers with cavities consisting of retroreflecting elements can give the potential for large-dynamic-range alignment-free operation, which makes the important applications of adaptive wireless laser power transfer/communication possible. In such an emerging approach based on resonant laser beam in the cavity, the laser is delivered to the photovoltaic cell for charging application (or photodiode for communication application) at the receiver automatically, without the necessity of positioning and aiming the receiver in conventional laser wireless power transfer techniques. The laser capable of operating alignment-free efficiently across large-dynamic-range is essential for the application. In this paper, the requirements on the dynamic range of alignment-free operation are summarized. An alignment-free laser with a cavity consisting of cat-eye retroreflectors is designed, and a large alignment-free dynamic range as never before is experimentally demonstrated. Telescope system in the laser cavity is adopted to suppress the beam expansion to enhance the working distance between the laser transmitter and the receiver. Coupled cavity scheme is used to decrease the laser intensity between the transmitter and the receiver for laser safety. By calculating the stability zone of the laser cavity, we found that the stability zone of the receiver cat-eye distance is quite narrow. Hence, the laser operation is very sensitive to the defocusing of the cat eye defocusing. Moreover, the cat eye defocusing induced by optical aberrations of spherical aberration and field curvature could be rather serious, when the long working distance results in a large beam size and the angle of incidence is large, hence limiting the effective working distance and the field of view of the alignment-free laser significantly. In the experiment, the improved optical designs with the aberrations compensated were adopted for large-dynamic-range alignment-free operation. The end-pumped Nd:GdVO₄ laser at 1063 nm could deliver over 5 W output within a working distance range of 1 m -5 m, and a receiver field of view of ±30°, without cavity realignment. The transmitter field of view reaching 4.6° (full width at half maximum) at a working distance of 5 m is also realized, with a corresponding receiver transverse movement range of 40 cm. Our work clarifies the optimizing criteria of the large-dynamic-range alignment-free laser based on cat-eye retroreflectors.

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Pursuing higher topological charge—larger angular indices m of high‐order Laguerre–Gaussian (LG) beams—is not only important for frontier applications like optical/quantum communication, optical tweezers, and super‐resolution imaging, but also involves a novel laser cavity and beam dynamics. Active methods to directly generate high‐order‐mode vortex beams from a laser cavity have excellent power handling and conversion efficiency, but struggle to achieve hundred‐level ultra‐high‐order LG modes. Here, the generation of ultra‐high‐order LG beams with m beyond 300 is demonstrated, utilizing the spherical aberration of a lens in the cavity of a simple end‐pumped Nd:YVO4 laser at 1064 nm. LG0,±m modes with m up to 317, selectable across a large range, are generated. With a simple model, how the mode selection relates to the cavity parameters is explained, and it is predicted that even higher order mode output can be expected by appropriate management of the elements’ aperture and laser gain. The approach provides a simple and flexible method to convert a wide range of lasers to generate ultra‐high‐order LG modes.