Speaker
Description
Perfect vortex beams (PVBs) effectively break the restriction where the annular ring size expands with increasing topological charges by reshaping the spatial spectrum of conventional orbital angular momentum (OAM) modes. However, conventional generation approaches typically rely on complex extra-cavity modulation systems, and the PVBs are strictly constrained to the Fourier plane, precluding long-distance propagation, which severely limits the practical applications of perfect vortex beams. To address this, here we report an integrated fiber laser based on metasurfaces, in which a metasurface is placed inside the laser cavity to partially modulate the oscillating beam; by utilizing a cubic freeform lens phase to precisely regulate the wavefront distribution and the corresponding curvature gradient of the optical field, a non-diffracting perfect vortex beam output is obtained, while the unmodulated portion continues to sustain the intra-cavity resonance. Notably, through the flexible design of the freeform lens phase, we further extend these non-diffracting perfect vortex beams to generalized morphologies with arbitrary shapes. Experimental results demonstrate that we have successfully achieved the direct lasing output of circular and polygonal perfect vortex beams with a non-diffracting distance exceeding 30 cm, and benefiting from the spin-decoupled phase modulation method of the metasurface, the flexible switching between non-diffracting perfect vortex beams with different topological charges (l = 10 and l = 30) is further realized. This architecture provides a mature design paradigm for integrated, tunable structured-light lasers, which is expected to promote the development of technologies such as high-capacity optical communications and far-field super-resolution imaging.
| I am the presenting author | Yes |
|---|