Low‐Threshold Whispering‐Gallery Mode Upconversion Lasing via Simultaneous Six‐Photon Absorption

Abstract

high-harmonic generation (HHG), the multiphoton absorption (MPA) upconversion lasing is an alternative approach to produce short wavelength laser sources. The MPA upconversion lasing is a typical higher-order nonlinear optical process in which the short wavelength lasing was realized through the stimulated emission between the up and low energy level; here, the population inversion was constructed by means of simultaneous MPA. [2] Comparing with traditional HHG techniques, the MPA upconversion lasing does not require stringent phase-matching requirements. [3,4] Hence, the tuning range of pumping light for MPA upconversion laser can be extended significantly. In addition, the MPA upconversion laser has a deep penetration depth compared with the conversion laser, which expands a great application value in biological imaging, [5] laser tomography, [6] photodynamic therapy, [7] and others. Ever since He et al. firstly demonstrated three-photon excited stimulated emission in organic dyes solution, [2] two-or three-photon absorption upconversion lasing has also been revealed in other organic dyes, [8,9] semiconductor quantum dots, [10] and perovskite nanocrystals. [11] However, the intrinsic liquid properties of organic dyes and the poor antiradiation ability of perovskite nanocrystals will be their bottleneck to practical applications drastically. Semiconductor crystal may be more suitable for such application due to its large damage resistance threshold and high optical gain. [12][13][14][15] Although two-and three-photon absorption upconversion lasing have been achieved in semiconductors such as ZnO, [16,17] only a few report on the above four-photon excited lasing to the best of our knowledge. [18] In order to realize higher-order MPA upconversion lasing, special attention has been paid to synthesize materials with large MPA cross-sections and large optical gain. [19] On the other hand, the MPA upconversion lasing is a typical high-order nonlinear photon-matter interaction process, which dramatically depends on the optical field intensity. Recently, the high-order nonlinear optical effect has been observed in high Q-factor microcavity. [20] It is anticipated that the manipulation of optical field through the construction of microcavity for the exciting light may be an alternative technique to achieve high-order MPA upconversion lasing. However, the short spatial gain length l g deduced from femtosecond (fs) laser pulse duration τ (l g = c·τ) will set a requirement forThe upconversion lasing through simultaneous multiphoton absorption (MPA) is a high-order nonlinear optical process, which enables many critical applications in the fluorescence imaging probe, laser tomography, and photodynamic therapy. Herein, the upconversion lasing from microwires via simultaneous six-photon absorption at room temperature is first realized. Moreover, the lasing peak and third-harmonic generation peak of pumping light are observed concurrently, while the temperature-dependent spectrum elucidates the essential distinction between each...

Lateral cavity enabled Fabry-Perot microlasers from all-inorganic perovskites

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Robust Polariton Bose–Einstein Condensation Laser via a Strong Coupling Microcavity

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Gradient Annealing as a New Strategy to Fabricate Gradient Nanoparticle Array on Microwires

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