[1] M Haase, H Schäfer. Upconverting nanoparticles. Angewandte Chemie International Edition, 50, 5808-5829(2011).

[2] D V Kozlov, F N Castellano. Anti−Stokes delayed fluorescence from metal−organic bichromophores. Chemical Communications, 46, 2860-2861(2004).

[3] Z Wang, J Zhao, Donato M Di. Increasing the anti−Stokes shift in TTA upconversion with photosensitizers showing red−shifted spin−allowed charge transfer absorption but a non-compromised triplet state energy level. Chemical Communications, 55, 1510-1513(2019).

[4] A Mahammed, K Chen, J Vestfrid. Phosphorus corrole complexes: from property tuning to applications in photocatalysis and triplet−triplet annihilation upconversion. Chemical Science, 10, 7091-7103(2019).

[5] Y Dong, B Dick, J Zhao. Twisted bodipy derivative as a heavy−atom−free triplet photosensitizer showing strong absorption of yellow light, intersystem crossing, and a high-energy long−lived triplet state. Organic Letters, 22, 5535-5539(2020).

[6] T Li, S Liu, H Zhang. Ultraviolet upconversion luminescence in Y₂O₃: Yb³⁺, Tm³⁺ nanocrystals and its application in photocatalysis. Journal of Materials Science, 46, 2882-2886(2011).

[7] G Xu, D Hu, X Zhao. Fluorescence upconversion properties of a class of improved pyridinium dyes induced by two−photon absorption. Optics & Laser Technology, 39, 690-695(2007).

[8] T N Singh-Rachford, F N Castellano. Photon upconversion based on sensitized triplet−triplet annihilation. Coordination Chemistry Reviews, 254, 2560-2573(2010).

[9] J Zhao, S Ji, H Guo. Triplet−triplet annihilation based upconversion: from triplet sensitizers and triplet acceptors to upconversion quantum yields. RSC Advances, 1, 937-950(2011).

[10] S Baluschev, T Miteva, V Yakutkin. Up−conversion fluorescence: noncoherent excitation by sunlight. Physical Review Letters, 97, 143903(2006).

[11] J Zhou, Q Liu, W Feng. Upconversion luminescent materials: advances and applications. Chemical Reviews, 115, 395-465(2015).

[12] T N Singh-Rachford, R R Islangulov, F N Castellano. Photochemical upconversion approach to broad−band visible light generation. The Journal of Physical Chemistry A, 112, 3906-3910(2008).

[13] D Hughes, J Barr. Laser diode pumped solid state lasers. Journal of Physics D: Applied Physics, 25, 563(1992).

[14] M Mailam, J Yao, P Wang. LD end−pumped 946 nm/473 nm continuous Nd:YAG/LBO laser. Infrared and Laser Engineering, 42, 2931-2934(2013).

[15] H Lin, X Meng, Y Xu. Implementation of tunable single−frequency optical parameter oscillator based on quasi−phase matching. Advances in Laser and Optoelectronics, 50, 34-39(2013).

[16] T Xing, L Wang, S Hu. Widely tunable and narrow−bandwidth pulsed mid−IR PPMgLN−OPO by self−seeding dual etalon−coupled cavities. Optics Express, 25, 31810-31815(2017).

[17] J Birks. The quintet state of the pyrene excimer. Physics Letters A, 24, 479-480(1967).

[18] [18] Liu Xibin, Ding Weiping. Development application of laser diode pumped DPSSL[J]. Journal of Hunan Institute of Science Technology (Natural Science Edition), 2005, 18 (3): 49−58. (in Chinese)

[19] Y Dong, A A Sukhanov, J Zhao. Spin−orbit charge−transfer intersystem crossing (SOCT−ISC) in bodipy−phenoxazine dyads: effect of chromophore orientation and conformation restriction on the photophysical properties. The Journal of Physical Chemistry C, 123, 22793-22811(2019).

[20] Z Wang, J Zhao, A Barbon. Radical−enhanced intersystem crossing in new Bodipy derivatives and application for efficient triplet−triplet annihilation upconversion. Journal of the American Chemical Society, 139, 7831-7842(2017).

[21] A Haefele, J R Blumhoff, R S Khnayzer. Getting to the (square) root of the problem: how to make noncoherent pumped upconversion linear. The Journal of Physical Chemistry Letters, 3, 299-303(2012).

[22] W Wu, H Guo, W Wu. Organic triplet sensitizer library derived from a single chromophore (BODIPY) with long−lived triplet excited state for triplet−triplet annihilation based upconversion. Journal of Organic Chemistry, 76, 7056-7064(2011).

[23] [23] Chen D W, Rose T S. In low noise 10W cw OPO generation near 3spl mum MgO doped PPLN[C]Conference on Lasers ElectroOptics, 2005: 18291831.

[24] M Razeghi, N Bandyopadhyay, Y Bai. Recent advances in mid infrared (3-5 μm) quantum cascade lasers. Optical Materials Express, 3, 1872-1884(2013).

[25] R Cramer, F Hillenkamp, R F Haglund. Infrared matrix−assisted laser desorption and ionization by using a tunable mid−infrared free−electron laser. Journal of the American Society for Mass Spectrometry, 7, 1187-1193(1996).

[26] S Tokita, M Murakami, S Shimizu. Liquid−cooled 24 W mid−infrared Er: ZBLAN fiber laser. Optics Letters, 34, 3062-3064(2009).

[27] O Henderson-Sapir, J Munch, D J Ottaway. Mid−infrared fiber lasers at and beyond 3.5 μm using dual−wavelength pumping. Optics Letters, 39, 493-496(2014).

[28] J Novak, M Windsor. Laser photolysis and spectroscopy: a new technique for the study of rapid reactions in the nanosecond time range. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 308, 95-110(1968).