Local Structure Design and Application of Rare-Earth Doped Alkaline Earth Fluorite Laser Crystal (Invited)

Liangbi Su; Fengkai Ma; Zhen Zhang; Dapeng Jiang; Zhonghan Zhang; Huamin Kou; Zhen Li; Zhenqiang Chen; Jun Xu

doi:10.3788/LOP231362

[1] Maiman T H. Stimulated optical radiation in ruby[J]. Nature, 187, 493-494(1960).

[2] Kaminskii A A. Laser crystals and ceramics: recent advances[J]. Laser & Photonics Reviews, 1, 93-177(2007).

[3] Norvig P, Relman D, Goldstein D et al. 2020 visions[J]. Nature, 463, 26-32(2010).

[4] Xue Y Y, Xu X D, Su L B et al. Research progress of mid-infrared laser crystals[J]. Journal of Synthetic Crystals, 49, 1347-1360(2020).

[5] Li N, Liu B, Shi J J et al. Research progress of rare-earth doped laser crystals in visible region[J]. Journal of Inorganic Materials, 34, 573-589(2019).

[6] Xu C L, Ma F K, Zhang Z et al. Research progress of visible laser crystals activated by Pr3+ ions[J]. Chinese Journal of Luminescence, 43, 1690-1704(2022).

[7] Cao W H, Li Z, Shi C K et al. Overview of research and development of Pr3+ doped solid-state lasers[J]. Opto-Electronic Engineering, 49, 210364(2022).

[8] Zhang Z, Su L B. Research progress of near 3 μm mid-infrared laser based on Er3+ doped single crystals[J]. Journal of Synthetic Crystals, 49, 1361-1368(2020).

[9] Kaminskii A A. Modern developments in the physics of crystalline laser materials[J]. Physica Status Solidi (a), 200, 215-296(2003).

[10] Wang J Y, Yu H H, Wu Y C et al. Recent developments in functional crystals in China[J]. Engineering, 1, 192-210(2015).

[11] Xu J. Development and thinking of laser crystal materials[J]. Laser & Optoelectronics Progress, 43, 17-24(2006).

[12] Liu W Y, Lu D Z, Pan S L et al. Ligand engineering for broadening infrared luminescence of Kramers ytterbium ions in disordered sesquioxides[J]. Crystal Growth & Design, 19, 3704-3713(2019).

[13] Lin L T, Wang Y P, Lan B J et al. Coordination geometry engineering in a doped disordered matrix for tunable optical response[J]. The Journal of Physical Chemistry C, 123, 29343-29352(2019).

[14] Ma F K, Jiang D P, Zhang Z et al. Tailoring the local lattice distortion of Nd3+ by codoping of Y3+ through first principles calculation for tuning the spectroscopic properties[J]. Optical Materials Express, 9, 4256-4272(2019).

[15] Xie G W, Fang L Z, Xia H P et al. Effective enhancement of ~2.86 µm mid-infrared emission of Na5Y9F32 single crystal co-doped Ho3+/Pr3+ introduced by Gd3+ ions[J]. Journal of Alloys and Compounds, 948, 169758(2023).

[16] Yu H H, Pan Z B, Zhang H J et al. Development of disordered laser crystals and their ultrafast lasers[J]. Journal of Synthetic Crystals, 50, 648-668, 583(2021).

[17] Zheng L W, Wu H, Zhang L L et al. Determination of cross-relaxation efficiency based on spectroscopy in thulium-doped rare-earth sesquioxides[J]. Ceramics International, 49, 11060-11066(2023).

[18] Ding S J, Zhang Q L, Peng F et al. Crystal growth, spectral properties and continuous wave laser operation of new mixed Nd∶GdYNbO4 laser crystal[J]. Journal of Alloys and Compounds, 698, 159-163(2017).

[19] Xia Z G, Ma C G, Molokeev M S et al. Chemical unit cosubstitution and tuning of photoluminescence in the Ca2(Al1-xMgx)(Al1-xSi1+x)O7∶Eu2+ phosphor[J]. Journal of the American Chemical Society, 137, 12494-12497(2015).

[20] Hu C, Feng X Q, Li J et al. Role of Y admixture in (Lu1-xYx)3Al5O12∶Pr ceramic scintillators free of host luminescence[J]. Physical Review Applied, 6, 064026(2016).

[21] Cao W Z, Mei D J, Yang Y et al. From CuFeS2 to Ba6Cu2FeGe4S16: rational band gap engineering achieves large second-harmonic-generation together with high laser damage threshold[J]. Chemical Communications, 55, 14510-14513(2019).

[22] Zhu J F, Wei L, Tian W L et al. Generation of sub-100 fs pulses from mode-locked Nd, Y∶SrF2 laser with enhancing SPM[J]. Laser Physics Letters, 13, 055804(2016).

[23] Qin Z P, Xie G Q, Ma J et al. Generation of 103 fs mode-locked pulses by a gain linewidth-variable Nd, Y∶CaF2 disordered crystal[J]. Optics Letters, 39, 1737-1739(2014).

[24] Chen J C, Peng Y J, Zhang Z X et al. Demonstration of a diode pumped Nd, Y co-doped SrF2 crystal based, high energy chirped pulse amplification laser system[J]. Optics Communications, 382, 201-204(2017).

[25] Tang X X, Qiu J S, Fan Z W et al. Diode-pumped medium-aperture-size square Nd, Y∶CaF2 rod amplifier for Inertial Confinement Fusion laser drivers[J]. Optical Materials, 58, 445-448(2016).

[26] Ma F K, Su F, Zhou R F et al. The defect aggregation of RE3+ (RE=Y, La~Lu) in MF2 (M=Ca, Sr, Ba) fluorites[J]. Materials Research Bulletin, 125, 110788(2020).

[27] Andeen C G, Link D, Fontanella J. Cluster-associated relaxations in rare-earth-doped calcium fluoride[J]. Physical Review B, 16, 3762-3767(1977).

[28] Andeen C G, Fontanella J J, Wintersgill M C et al. Clustering in rare-earth-doped alkaline earth fluorides (dielectric relaxation)[J]. Journal of Physics C: Solid State Physics, 14, 3557-3574(1981).

[29] den Hartog H W, Pen K F, Meuldijk J. Defect structure and charge transport in solid solutions Ba1-xLaxF2+x[J]. Physical Review B, 28, 6031-6040(1983).

[30] Kaminskii A A, Osico V V, Prochorov A M et al. Spectral investigation of the stimulated radiation of Nd3+ in CaF2-YF3[J]. Physics Letters, 22, 419-421(1966).

[31] Voronko Y K, Osiko V V, Shcherbakov I A. Investigation of the interaction of Nd3+ ions in CaF2, SrF2, and BaF2 crystals (type I)[J]. Soviet Physics-JETP, 28, 838-844(1969).

[32] Cheetham A K, Fender B F, Cooper M J. Defect structure of calcium fluoride containing excess anions I. Bragg scattering[J]. Journal of Physics C: Solid State Physics, 4, 3107-3121(1971).

[33] Catlow C R A. Defect clusters in doped fluorite crystals[J]. Journal of Physics C: Solid State Physics, 6, L64-L70(1973).

[34] Corish J, Catlow C R A, Jacobs P W M et al. Defect aggregation in anion-excess fluorites. dopant monomers and dimers[J]. Physical Review B, 25, 6425-6438(1982).

[35] Bendall P J, Catlow C R A, Corish J et al. Defect aggregation in anion-excess fluorites II. Clusters containing more than two impurity atoms[J]. Journal of Solid State Chemistry, 51, 159-169(1984).

[36] Catlow C R A, Chadwick A V, Greaves G N et al. Direct observations of the dopant environment in fluorites using EXAFS[J]. Nature, 312, 601-604(1984).

[37] Laval J P, Frit B. Defect structure of anion-excess fluorite-related Ca1-xYxF2+x solid solutions[J]. Journal of Solid State Chemistry, 49, 237-246(1983).

[38] Bevan D J M, Strähle J, Greis O. The crystal structure of tveitite, an ordered yttrofluorite mineral[J]. Journal of Solid State Chemistry, 44, 75-81(1982).

[39] Lacroix B, Genevois C, Doualan J L et al. Direct imaging of rare-earth ion clusters in Yb∶CaF2[J]. Physical Review B, 90, 125124(2014).

[40] Cai J J, Ma C G, Yin M. Factors influencing the structure of the complex-defects in AF2∶RE3+ (A=Ca, Sr and Ba): a first-principles study[J]. Journal of Luminescence, 250, 119058(2022).

[41] Sulyanova E A, Sobolev B P. The universal defect cluster architecture of fluorite-type nanostructured crystals[J]. CrystEngComm, 24, 3762-3769(2022).

[42] Ma F K, Zhang Z, Jiang D P et al. Neodymium cluster evolution in fluorite laser crystal: a combined DFT and synchrotron X-ray absorption fine structure study[J]. Crystal Growth & Design, 22, 4480-4493(2022).

[43] Ma F K, Jiang D P, Su L B et al. Spectral properties and highly efficient continuous-wave laser operation in Nd-doped Sr1-xYxF2+x crystals[J]. Optics Letters, 41, 501-503(2016).

[44] Ma W W, Su L B, Xu X D et al. Improved 2.79 μm continuous-wave laser performance from a diode-end pumped Er, Pr∶CaF2 crystal[J]. Journal of Alloys and Compounds, 695, 3370-3375(2017).

[45] Wang Y H, Li Z, Yin H et al. Enhanced ~3 μm mid-infrared emissions of Ho3+ via Yb3+ sensitization and Pr3+ deactivation in Lu3Al5O12 crystal[J]. Optical Materials Express, 8, 1882-1889(2018).

[46] Tang Q Y, Ma F K, Zhang Z et al. Rare-earth induced nonlinear structural evolutions in fluorite solid solution crystals[J]. Optical Materials Express, 11, 3870-3879(2021).

[47] Ma F K, Zhou H Q, Tang Q Y et al. Clusters modification for tunable photoluminescence in Nd3+∶SrF2 crystal[J]. Journal of Alloys and Compounds, 899, 162913(2022).

[48] Gao Z Y, Zhu J F, Wang J L et al. Diode-pumped Kerr-lens mode-locked femtosecond Yb∶YAG ceramic laser[C](2016).

[49] Pirzio F, Fregnani L, Volpi A et al. 87 fs pulse generation in a diode-pumped semiconductor saturable absorber mirror mode-locked Yb∶YLF laser[J]. Applied Optics, 55, 4414-4417(2016).

[50] Bain F M, Lagatsky A A, Brown C T A et al. High-power Kerr-lens mode-locked ytterbium lasers[J]. Proceedings of SPIE, 6871, 68712L(2008).

[51] Akbari R, Fedorova K A, Rafailov E U et al. Diode-pumped ultrafast Yb∶KGW laser with 56 fs pulses and multi-100 kW peak power based on SESAM and Kerr-lens mode locking[J]. Applied Physics B, 123, 123(2017).

[52] Paradis C, Modsching N, Wittwer V J et al. Generation of 35-fs pulses from a Kerr lens mode-locked Yb∶Lu2O3 thin-disk laser[J]. Optics Express, 25, 14918-14925(2017).

[53] Lucca A, Debourg G, Jacquemet M et al. High-power diode-pumped Yb3+∶CaF2 femtosecond laser[J]. Optics Letters, 29, 2767-2769(2004).

[54] Sévillano P, Machinet G, Dubrasquet R et al. High-power sub-50 fs, Kerr-lens mode-locked Yb∶CaF2 oscillator pumped by a high-brightness fiber-laser[C](2014).

[55] Kahle M, Körner J, Hein J et al. Performance of a quantum defect minimized disk laser based on cryogenically cooled Yb∶CaF2[J]. Optics & Laser Technology, 92, 19-23(2017).

[56] Wentsch K S, Weichelt B, Günster S et al. Yb∶CaF2 thin-disk laser[J]. Optics Express, 22, 1524-1532(2014).

[57] Su L B, Xu J, Li H J et al. Codoping Na+ to modulate the spectroscopy and photoluminescence properties of Yb3+ in CaF2 laser crystal[J]. Optics Letters, 30, 1003-1005(2005).

[58] Su L B, Xu J, Li H J et al. Sites structure and spectroscopic properties of Yb-doped and Yb, Na-codoped CaF2 laser crystals[J]. Chemical Physics Letters, 406, 254-258(2005).

[59] Xu J, Su L B, Zhang D et al. Thermal, spectroscopic and laser properties of Yb3+, Na+∶CaF2 single crystals[J]. Journal of Crystal Growth, 291, 267-271(2006).

[60] Pugžlys A, Andriukaitis G, Sidorov D et al. Spectroscopy and lasing of cryogenically cooled Yb, Na∶CaF2[J]. Applied Physics B, 97, 339-350(2009).

[61] Pugžlys A, Sidorov D, Ali T et al. Spectroscopic and lasing properties of cryogenically cooled Yb, Na∶CaF2[C], MF4(2008).

[62] Ge W Q, Chai L, Yan J et al. High power continuous-wave operation and dynamics of soliton mode-locked Yb, Na∶CaF2 lasers at room temperature[J]. IEEE Journal of Quantum Electronics, 47, 977-983(2011).

[63] Su L B, Xu J, Xue Y H et al. Low-threshold diode-pumped Yb3+, Na+∶CaF2 self-Q-switched laser[J]. Optics Express, 13, 5635-5640(2005).

[64] Du J, Liang X Y, Wang Y G et al. 1 ps passively mode-locked laser operation of Na, Yb∶CaF2 crystal[J]. Optics Express, 13, 7970-7975(2005).

[65] Pugžlys A, Andriukaitis G, Baltuška A et al. 1-kHz-repetition-rate millijoule femtosecond cryocooled DPSS Yb, Na∶CaF2 regenerative amplifier[C], WD3(2009).

[66] Siebold M, Hornung M, Boedefeld R et al. Terawatt diode-pumped Yb∶CaF2 laser[J]. Optics Letters, 33, 2770-2772(2008).

[67] Aus der Au J, Kopf D, Morier-Genoud F et al. 60-fs pulses from a diode-pumped Nd∶glass laser[J]. Optics Letters, 22, 307-309(1997).

[68] Hu L L, Chen S B, Tang J P et al. Large aperture N31 neodymium phosphate laser glass for use in a high power laser facility[J]. High Power Laser Science and Engineering, 2, e1(2014).

[69] He D B, Kang S A, Zhang L Y et al. Research and development of new neodymium laser glasses[J]. High Power Laser Science and Engineering, 5, e1(2017).

[70] Yang S D, Yin D J, Gan Z B et al. Thermal effect of high energy repetition rate Nd∶glass laser[J]. Chinese Journal of Lasers, 47, 0901004(2020).

[71] Ma F K, Jiang D P, Tang F et al. Modulated photoluminescence parameters of neodymium in Sr0.95Y0.05F2.05 laser crystal[J]. Optical Materials Express, 7, 3231-3237(2017).

[72] Ma F K, Jiang D P, Su L B et al. The codopant assisted tunable photoluminescence and highly efficient CW lasers in Nd3+∶SrF2 crystal[J]. Journal of Luminescence, 219, 116911(2020).

[73] Iffländer R, Iffländer R. Laser glasses[M]. Solid-state lasers for materials processing. Springer series in optical sciences, 77, 311-318(2001).

[74] Yu H H, Liu J H, Zhang H J et al. Advances in vanadate laser crystals at a lasing wavelength of 1 micrometer[J]. Laser & Photonics Reviews, 8, 847-864(2014).

[75] Barnes N P, Storm M E, Cross P L et al. Efficiency of Nd laser materials with laser diode pumping[J]. IEEE Journal of Quantum Electronics, 26, 558-569(1990).

[76] Shen H Y, Zeng R R, Zhou Y P et al. Simultaneous multiple wavelength laser action in various neodymium host crystals[J]. IEEE Journal of Quantum Electronics, 27, 2315-2318(1991).

[77] Demidovich A A, Shkadarevich A P, Danailov M B et al. Comparison of cw laser performance of Nd∶KGW, Nd∶YAG, Nd∶BEL, and Nd∶YVO4 under laser diode pumping[J]. Applied Physics B, 67, 11-15(1998).

[78] Li D Z, Xu X D, Cheng S S et al. Polarized spectral properties of Nd3+ ions in CaYAlO4 crystal[J]. Applied Physics B, 101, 199-205(2010).

[79] Li S T, Zhang X Y, Wang Q P et al. A discussion on the effective stimulated emission cross section of R2→Y3 transition of Nd∶YAG crystal[J]. Laser & Infrared, 34, 157-158(2004).

[80] Pan S D. Study on crystal characteristics of Nd∶YLF and all-solid-state laser[D](2007).

[81] Zhang F, Fan X W, Liu J et al. Dual-wavelength mode-locked operation on a novel Nd3+, Gd3+∶SrF2 crystal laser[J]. Optical Materials Express, 6, 1513-1519(2016).

[82] Zhang F, Liu J J, Liu J et al. Efficient continuous-wave and 739 fs mode-locked laser on a novel Nd3+, La3+co-doped SrF2 disordered crystal[J]. Laser Physics Letters, 13, 095802(2016).

[83] Deng W P, Yang T, Cao J P et al. High-efficiency 1064 nm nonplanar ring oscillator Nd∶YAG laser with diode pumping at 885 nm[J]. Optics Letters, 43, 1562-1565(2018).

[84] Li X D, Yu X, Chen F et al. Laser properties of continuous-grown Nd∶GdVO4/GdVO4 and Nd∶YVO4/YVO4 composite crystals under direct pumping[J]. Optics Express, 17, 12869-12874(2009).

[85] Deana A M, Wetter N U. Double-beam, mode-controlling diode side-pumped Nd∶YLF laser with near 60% efficiency[J]. Proceedings of SPIE, 9342, 93420Z(2015).

[86] Ma J, Pan Z B, Cai H Q et al. Sub-80 femtosecond pulses generation from a diode-pumped mode-locked Nd∶Ca3La2(BO3)4 disordered crystal laser[J]. Optics Letters, 41, 1384-1387(2016).

[87] Krennrich D, Knappe R, Henrich B et al. A comprehensive study of Nd∶YAG, Nd∶YAlO3, Nd∶YVO4 and Nd∶YGdVO4 lasers operating at wavelengths of 0.9 and 1.3 μm. Part 1: cw-operation[J]. Applied Physics B, 92, 165-174(2008).

[88] Guo Y D, Peng Q J, Bo Y et al. 24.6 kW near diffraction limit quasi-continuous-wave Nd∶YAG slab laser based on a stable-unstable hybrid cavity[J]. Optics Letters, 45, 1136-1139(2020).

[89] Goodberlet J, Jacobson J, Fujimoto J G et al. Self-starting additive-pulse mode-locked diode-pumped Nd∶YAG laser[J]. Optics Letters, 15, 504-506(1990).

[90] Yan X P, Liu Q, Fu X et al. A 108 W, 500 kHz Q-switching Nd∶YVO4 laser with the MOPA configuration[J]. Optics Express, 16, 3356-3361(2008).

[91] Fan Y X, He J L, Wang Y G et al. 2-ps passively mode-locked Nd∶YVO4 laser using an output-coupling-type semiconductor saturable absorber mirror[J]. Applied Physics Letters, 86, 101103(2005).

[92] Ye Z B, Liu C, Tu B et al. Kilowatt-level direct-‘refractive index matching liquid’-cooled Nd∶YLF thin disk laser resonator[J]. Optics Express, 24, 1758-1772(2016).

[93] Keller U, Chiu T H, Ferguson J F. Self-starting and self-Q-switching dynamics of passively mode-locked Nd∶YLF and Nd∶YAG lasers[J]. Optics Letters, 18, 217-219(1993).

[94] Li D Z. Study of growth and properties of Yb/Nd doped ultrafast laser crystals[D](2012).

[95] Zhu H Y, Zhang Y C, Duan Y M et al. Disordered Nd∶CaYAlO4 crystal lasing at 1069, 1080 and 1363 nm[J]. Journal of Luminescence, 195, 225-227(2018).

[96] Liu S D, Dong L L, Xu Y et al. Femtosecond pulse generation with an a-cut Nd∶CaYAlO4 disordered crystal[J]. Applied Optics, 55, 7659-7662(2016).

[97] Agnesi A, Dell’Acqua S, Guandalini A et al. Optical spectroscopy and diode-pumped laser performance of Nd3+ in the CNGG crystal[J]. IEEE Journal of Quantum Electronics, 37, 304-313(2001).

[98] Yu Y G, Wang J Y, Zhang H J et al. Thermal characterization of lowly Nd3+ doped disordered Nd∶CNGG crystal[J]. Optics Express, 17, 9270-9275(2009).

[99] Mukhopadhyay P K, Ranganathan K, George J et al. 1.6 W of TEM00 cw output at 1.06 μm from Nd∶CNGG laser end-pumped by a fiber-coupled diode laser array[J]. Optics & Laser Technology, 35, 173-180(2003).

[100] Xie G Q, Qian L J, Yuan P et al. Generation of 534 fs pulses from a passively mode-locked Nd∶CLNGG-CNGG disordered crystal hybrid laser[J]. Laser Physics Letters, 7, 483-486(2010).

[101] Qin Z P, Qiao Z, Xie G Q et al. Femtosecond and dual-wavelength picosecond operations of Nd, La∶SrF2 disordered crystal laser[J]. IEEE Photonics Journal, 9, 1502007(2017).

[102] Pang S Y, Ma F K, Yu H et al. Highly efficient continuous-wave laser operation of LD-pumped Nd, Gd∶CaF2 and Nd, Y∶CaF2 crystals[J]. Laser Physics Letters, 15, 055802(2018).

[103] Pan Z B, Cong H J, Yu H H et al. Growth, thermal properties and laser operation of Nd∶Ca3La2(BO3)4: a new disordered laser crystal[J]. Optics Express, 21, 6091-6100(2013).

[104] Agnesi A, Carrà L, Reali G. Phosphate Nd∶glass materials for femtosecond pulse generation[J]. Optical Materials, 30, 1828-1831(2008).

[105] Li X H, Hao Q Q, Jiang D P et al. Smooth and flat photoluminescence spectra of Nd3+ active ions in tri-doped CaF2 single crystals[J]. Optical Materials Express, 10, 704-714(2020).

[106] Meroni C. New laser amplifier materials at 1053 nm[D](2022).

[107] Meroni C, Braud A, Doualan J L et al. Spectroscopy and laser gain measurements of CaF2∶Nd, X3+, Z3+ (X, Z=Gd, La, Ce, Y, Lu, Sc) crystals for broadband lasers applications[J]. Journal of Luminescence, 252, 119336(2022).

[108] Pollack S A, Chang D B. Ion-pair upconversion pumped laser emission in Er3+ ions in YAG, YLF, SrF2, and CaF2 crystals[J]. Journal of Applied Physics, 64, 2885-2893(1988).

[109] Pollnan M, Jackson S D. Erbium 3 μm fiber lasers[J]. IEEE Journal of Selected Topics in Quantum Electronics, 7, 30-40(2001).

[110] Zhang Z, Guo X S, Wang J Y et al. High-efficiency 2 μm continuous-wave laser in laser diode-pumped Tm3+, La3+∶CaF2 single crystal[J]. Optics Letters, 43, 4300-4303(2018).

[111] Wang Y X, Liu W X, Zhang Z H et al. Laser-diode-pumped Tm∶SrF2 single crystal for high efficiency CW laser operation at ∼2 µm[J]. Optics Letters, 47, 1117-1120(2022).

[112] Liu P, Jin L, Liu X et al. High efficiency Tm∶YAG slab laser with hundred-watts-level output power[J]. Applied Optics, 55, 2498-2502(2016).

[113] Mao Y F, Long Q L, Gao J M et al. 315 W, 1.94 μm, Tm∶YAP Innoslab laser[J]. Laser Physics, 33, 025002(2023).

[114] Ding Y, Han L, Yao B Q et al. High power Tm∶YLF bulk laser wavelength-stabilized by two F-P etalons[J]. Optik, 126, 990-992(2015).

[115] Demirbas U, University A B, Thesinga J et al. Continuous-wave Tm∶YLF laser with ultrabroad tuning (1772-2145 nm)[J]. Optics Express, 30, 41219-41239(2022).

[116] Zharikov E V, Zhekov V I, Kulevskii L A et al. Stimulated emission from Er3+ ions in yttrium aluminum garnet crystals at λ=2.94 μm[J]. Soviet Journal of Quantum Electronics, 4, 1039-1040(1975).

[117] Zhang Z, Wu Q H, Wang Y X et al. Efficient 2.76 μm continuous-wave laser in extremely lightly Er-doped CaF2 single-crystal fiber[J]. Laser Physics Letters, 17, 085801(2020).

[118] Zhang Z. Study on local structure, spectral properties and laser performance of Er3+ doped CaF2/SrF2 crystals[D](2021).

[119] Liu J J, Feng X Y, Fan X W et al. Efficient continuous-wave and passive Q-switched mode-locked Er3+∶CaF2-SrF2 lasers in the mid-infrared region[J]. Optics Letters, 43, 2418-2421(2018).

[120] Zong M Y, Wang Y F, Zhang Z et al. High-power 2.8 μm lasing in a lightly-doped Er∶CaF2 crystal[J]. Journal of Luminescence, 250, 119089(2022).

[121] Wang Y F, Ma F K, Zhang Z et al. Revisiting the self-termination effect of erbium based near 3 μm mid-infrared lasers[J]. Journal of Luminescence, 252, 119339(2022).

[122] Švejkar R, Šulc J, Jelínková H et al. Diode-pumped Er∶SrF2 laser tunable at 2.7 μm[J]. Optical Materials Express, 8, 1025-1030(2018).

[123] Liu J J, Fan X W, Liu J E et al. Mid-infrared self-Q-switched Er, Pr∶CaF2 diode-pumped laser[J]. Optics Letters, 41, 4660-4663(2016).

[124] Nie H K, Wang F F, Liu J T et al. Rare-earth ions-doped mid-infrared (2.7‒3 µm) bulk lasers: a review[J]. Chinese Optics Letters, 19, 091407(2021).

[125] Wyss C, Lüthy W, Weber H P et al. Emission properties of an optimised 2.8 μm Er3+∶YLF laser[J]. Optics Communications, 139, 215-218(1997).

[126] Ye X L, Xu X F, Ren H J et al. Enhanced high-slope-efficiency and high-power LD side-pumped Er∶YSGG laser[J]. Applied Optics, 58, 9949-9954(2019).

[127] You L, Lu D Z, Pan Z B et al. High-efficiency 3 μm Er∶YGG crystal lasers[J]. Optics Letters, 43, 5873-5876(2018).

[128] Fan M Q, Li T, Zhao J et al. Continuous wave and ReS2 passively Q-switched Er∶SrF2 laser at ∼3 μm[J]. Optics Letters, 43, 1726-1729(2018).

[129] Liang F, He C, Lu D Z et al. Multiphonon-assisted lasing beyond the fluorescence spectrum[J]. Nature Physics, 18, 1312-1316(2022).