Metalens Based Circularly Polarized Surface Emitting Perovskite Microlaser

Since the invention of lasers in the 1960s,lasers have become an indispensable part of people's lives.Especially since the invention of semiconductor lasers,their small size,light weight,high efficiency,and long working life have been increasingly developed.For applications,semiconductor lasers are also developing in the direction of miniaturization and miniaturization,and have great potential in the fields of optical imaging,optical sensing and communications.Perovskite has become a research hotspot in semiconductor materials because of its excellent photoelectric properties,simple preparation process,controllable band gap and high electron-hole ratio.Perovskite microlasers have been extensively studied because of their low threshold and simple preparation.Although various microlasers have been synthesized,most of them are linearly polarized,so they are limited in many application scenarios,such as chiral resolution in synthetic chemistry,cancerous tissue or nuclei imaging,high-density information storage and processing,etc.As a material that controls the light field at the sub-wavelength scale,metasurfaces have become a research hotspot in recent years because of their advantages of miniaturization and integration.The metalens extracts the phase distribution of the traditional lens,and uses the light field control ability of the metasurface to achieve focusing and imaging of traditional lens.In this paper,the metalens is combined with the perovskite single crystal to realize a perovskite laser with high directivity and pure circular polarization,where the perovskite nanowire is used as the resonator of the laser,and the metalens regulates the polarization of the laser.Metalens and achromatic metalens are designed here.Simulate the optical characteristics of ordinary metalenses and achromatic metalenses.For ordinary metalenses,the efficiency at the design wavelength of 520 nm is over 80%,and the airy disk has a half-width of 580 nm to reach the diffraction limit focusing;for achromatic metalenses.The efficiency of visible light band can reach more than20%,and it can reach 60%at 550 nm.The metalens was successfully prepared by using micro-nano processing technology.A metalens with a numerical aperture of 0.47,a focal length of 200?m,and a diameter of 200?m.By measuring the airy disk at the focal point of the metalens,the FWHM is 0.68?m,the Strehl ratio is 0.81,and the focusing efficiency at 520 nm is 60%.The linearly polarized laser is converted to a collimated circularly polarized laser.The Ti O₂ metalens is combined with a perovskite single crystal.The perovskite single crystal is used as a resonant cavity.The metalens converts the right-handed component in the linearly polarized light emitted by the perovskite single crystal into a left-handed component and diverges.The left-handed component is converted into right-handed light to achieve the collimation effect.Two concentric light spots with different intensities can be found.After polarization analysis,the smaller light spot is right-handed circularly polarized light,and the larger light spot is left-handed circularly polarized light,and the light intensity ratio is 0.555:0.445.The spot size of the right-handed collimated light at 2.213 mm was measured to be 235?m,and the intensity ratio was 0.993:0.007,and the left-handed circularly polarized light was almost completely lost.The divergence angle of the collimated light was calculated to be less than 0.9°,a perovskite laser emitting from a low-threshold circularly polarized surface based on a metalens is realized.