高功率激光与“超热导”激光晶体

人工晶体学报 ›› 2022, Vol. 51 ›› Issue (9-10): 1560-1572.

高功率激光与“超热导”激光晶体

张振¹, 樊仲维², 苏良碧¹

1.中国科学院上海硅酸盐研究所,上海 200050;
2.中国科学院空天信息创新研究院,北京 100094

收稿日期:2022-08-01 出版日期:2022-10-15 发布日期:2022-11-02
通信作者: 苏良碧,博士,研究员。E-mail:suliangbi@mail.sic.ac.cn
樊仲维,博士,研究员。E-mail:fanzhongwei@aoe.ac.cn
作者简介:张振(1993—),男,湖北省人,博士研究生。E-mail:zhangzhen@mail.sic.ac.cn。
苏良碧,博士,中国科学院上海硅酸盐研究所研究员、博士生导师。现任中国科学院上海硅酸盐研究所副所长,兼任《人工晶体学报》副主编,《无机材料学报》、Applied Optics等期刊编委,中国激光杂志社青年编委。主要研究方向为人工晶体、激光材料,长期开展宽光谱激光材料、高功率激光晶体与单晶光纤,以及超大尺寸人工晶体制备技术的研发。国家杰出青年基金获得者,曾获海市科技系统青年五四奖章、中国硅酸盐学会青年科技奖、中国科学院青年创新促进会优秀会员等。
樊仲维,研究员、博士生导师。现任中国科学院空天信息创新研究院副院长,兼任国家半导体泵浦激光工程技术研究中心主任、国家激光器件质量监督检验中心主任、全国光电测量标准化技术委员会主任委员、中国光学学会常务理事。主要研究方向为全固态短脉冲激光技术及应用,长期从事以高功率和高光束质量为主要特征的钕玻璃激光放大技术、皮秒/纳秒脉宽全固态激光技术等研究工作。获得政府特殊津贴,入选国家级新世纪百千万人才工程、科技北京百名领军人才培养工程,获得国家技术发明奖二等奖、国家科学技术进步奖二等奖、北京市科学技术奖一等奖、中国科学院杰出科技成就奖、光华工程科技奖等。
基金资助:
国家杰出青年科学基金(61925508);国家青年科学基金(61905265);中科院稳定支持基础研究领域青年团队计划(YSBR-024);上海市科学技术委员会项目(2051107400,20520750200);中科院“一带一路”国际合作项目(121631KYSB20200039)

High-Power Laser and Ultra-High Thermal Conductivity Laser Crystals

ZHANG Zhen¹, FAN Zhongwei², SU Liangbi¹

1. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China;
2. Aerospace Information Research of Optoelectronics, Chinese Academy of Sciences, Beijing 100094, China

Received:2022-08-01 Online:2022-10-15 Published:2022-11-02

摘要/Abstract

摘要： 高功率固体激光技术的发展史就是一部与“废热”的斗争史,为抑制热效应对光束质量的不利影响,先后出现了热容激光器、薄片激光器、板条激光器以及光纤激光器,新的增益介质形态结合先进的散热技术将激光输出功率提升至百千瓦量级。固体激光增益介质的热学性能是限制激光功率进一步取得突破的重要瓶颈。因此,寻找具备超高热导率的激光晶体材料意义重大。本文介绍了上述四种激光器的基本原理及其在高功率激光方面取得的研究进展,从提高增益介质材料热导率的角度出发,对目前已有的方法和研究成果进行了分析与总结,对超热导激光晶体研究和高功率激光技术的发展进行了展望。

关键词: 高功率激光, 热效应, 激光晶体, 超高热导率, 热容激光器, 薄片激光器, 板条激光器, 光纤激光器

Abstract: The development of high-power solid state laser technology is a course of struggling against the "waste heat" generated with lasering. The most critical issue for the development of high-power solid-state lasers is how to suppress the thermal effect on the beam quality under high-power operating conditions. To improve this adverse effect researchers invented heat capacity laser, thin-film laser, slab laser and fiber laser. These new designs of lasers based on novel form of gain medium combined with advanced heat dissipation technology have enhanced the output power to about one hundred kilowatts. However, the thermal properties of the solid state gain medium have become the critical bottleneck restricting further breakthroughs in laser power. Therefore, it is of great significance to explore the novel laser crystal materials with ultra-high thermal conductivity. This paper introduces the basic principles of the above four lasers and their research progress in high-power lasers. From the perspective of improving the thermal conductivity of gain medium materials, the existing methods and related results are analyzed and summarized. The research on ultra-high thermal conducting laser crystals and the development of high-power laser technology are also prospected.

Key words: high-power laser, thermal effect, laser crystal, ultra-high thermal conductivity, heat capacity laser, thin disk laser, slab laser, fiber laser

中图分类号:

O734

张振, 樊仲维, 苏良碧. 高功率激光与“超热导”激光晶体[J]. 人工晶体学报, 2022, 51(9-10): 1560-1572.

ZHANG Zhen, FAN Zhongwei, SU Liangbi. High-Power Laser and Ultra-High Thermal Conductivity Laser Crystals[J]. JOURNAL OF SYNTHETIC CRYSTALS, 2022, 51(9-10): 1560-1572.

参考文献

[1] MAIMAN T H. Stimulated optical radiation in ruby[J]. Nature, 1960, 187(4736): 493-494.
[2] GOULIELMAKIS E, SCHULTZE M, HOFSTETTER M, et al. Single-cycle nonlinear optics[J]. Science, 2008, 320(5883): 1614-1617.
[3] VINCENTI H, QUÉRÉ F. Attosecond lighthouses: how to use spatiotemporally coupled light fields to generate isolated attosecond pulses[J]. Physical Review Letters, 2012, 108(11): 113904.
[4] LI W Q, GAN Z B, YU L H, et al. 339 J high-energy Ti∶sapphire chirped-pulse amplifier for 10 PW laser facility[J]. Optics Letters, 2018, 43(22): 5681-5684.
[5] AYDIN Y O, FORTIN V, VALLÉE R, et al. Towards power scaling of 2.8 μm fiber lasers[J]. Optics Letters, 2018, 43(18): 4542-4545.
[6] 雷小丽,孙玲,刘洋,等.达信公司百千瓦陶瓷激光器技术综述[J].激光与红外,2011,41(9):948-952.
LEI X L, SUN L, LIU Y, et al. Laser with 100 kW output power developed by the Textron company[J]. Laser ＆ Infrared, 2011, 41(9): 948-952(in Chinese).
[7] INJEYAN H, GOODNO G D, PENN M, et al. High-power laser handbook[M]. New York: McGraw-Hill, 2011
[8] 陈金宝,郭少锋.高能固态激光器技术路线分析[J].中国激光,2013,40(6):69-75.
CHEN J B, GUO S F. Review on technical approaches of high energy solid-state lasers[J]. Chinese Journal of Lasers, 2013, 40(6): 69-75(in Chinese).
[9] ALBRECHT G F, SUTTON S B, GEORGE E V, et al. Solid state heat capacity disk laser[J]. Laser and Particle Beams, 1998, 16(4): 605-625.
[10] WALTERS C T, DULANEY J L, CAMPBELL B E, et al. Nd-glass burst laser with kW average power output[J]. IEEE Journal of Quantum Electronics, 1995, 31(2): 293-300.
[11] YAMAMOTO R M, PARKER J M, ALLEN K L, et al. Evolution of a solid state laser[C]//Defense and Security Symposium. Proc SPIE 6552, Laser Source Technology for Defense and Security III, Orlando, Florida, USA. 2007, 6552: 24-33.
[12] YAMAMOTO R M, BHACHU B S, CUTTER K P, et al. The use of large transparent ceramics in a high powered, diode pumped solid state laser[J]. 2008: WC5.
[13] LAFORTUNE K N, HURD R L, JOHANSSON E M, et al. Intracavity adaptive correction of a 10-kW solid state heat-capacity laser[C]//Lasers and Applications in Science and Engineering. Proc SPIE 5333, Laser Resonators and Beam Control VII, San Jose, Ca, USA. 2004, 5333: 53-61.
[14] VETROVEC J. Compact active mirror laser (CAMIL)[C]//High-Power Lasers and Applications. Proc SPIE 4630, Solid State Lasers XI, San Jose, California, USA. 2002, 4630: 1-12.
[15] KALISKY Y Y, KALISKY O. The status of high-power lasers and their applications in the battlefield[C]//2010: 091003.
[16] VETROVEC J, KOUMVAKALIS A, SHAH R D, et al. Development of solid state disk laser for high-average power[C]//High-Power Lasers and Applications. Proc SPIE 4968, Solid State Lasers XII, San Jose, CA, USA. 2003, 4968: 54-64.
[17] STEWEN C, CONTAG K, LARIONOV M, et al. A 1-kW CW thin disc laser[J]. IEEE Journal of Selected Topics in Quantum Electronics, 2000, 6(4): 650-657.
[18] AVIZONIS P V, BOSSERT D J, CURTIN M S, et al. Physics of high performance YB∶YAG thin disk lasers[C]//Conference on Lasers and Electro-Optics. Optical Society of America, 2009: CThA2.
[19] RICHARDSON D J, NILSSON J, CLARKSON W A. High power fiber lasers: current status and future perspectives[J]. Journal of the Optical Society of America B, 2010, 27(11): B63-B92.
[20] STILES E. New developments in IPG fiber laser technology[C]//Proceedings of the 5th International Workshop on Fiber Lasers. 2009: 2.
[21] SHINER B. The impact of fiber laser technology on the world wide material processing market[C]//CLEO: Applications and Technology. Optical Society of America, 2013: AF2 J.1.
[22] OTTO H J, JAUREGUI C, LIMPERT J, et al. Average power limit of fiber-laser systems with nearly diffraction-limited beam quality[C]// Fiber Lasers XIII: Technology, Systems, and Applications. Proc SPIE 9728, San Jose, California, USA. 2016, 9728: 82-87.
[23] 刘兆军,高悉宝,丛振华,等.晶体光纤及晶体衍生光纤制备与应用综述[J].光子学报,2019,48(11):28-46.
LIU Z J, GAO X B, CONG Z H, et al. Crystal fiber and crystal-derived fiber preparation and application: a review[J]. Acta Photonica Sinica, 2019, 48(11): 28-46(in Chinese).
[24] DÉLEN X, PIEHLER S, DIDIERJEAN J, et al. 250 W single-crystal fiber Yb∶YAG laser[J]. Optics Letters, 2012, 37(14): 2898-2900.
[25] DUBINSKII M, ZHANG J, FROMZEL V, et al. Low-loss ‘crystalline-core/crystalline-clad’ (C4) fibers for highly power scalable high efficiency fiber lasers[J]. Optics Express, 2018, 26(4): 5092-5101.
[26] CAHILL D G, LEE S M, SELINDER T I. Thermal conductivity of κ-Al₂O₃ and α-Al₂O₃ wear-resistant coatings[J]. Journal of Applied Physics, 1998, 83(11): 5783-5786.
[27] GRIEBNER U, PETROV V, PETERMANN K, et al. Passively mode-locked Yb∶Lu₂O₃ laser[J]. Optics Express, 2004, 12(14): 3125-3130.
[28] BERMAN R, SIMON F E, WILKS J. Thermal conductivity of dielectric crystals: the ‘umklapp’ process[J]. Nature, 1951, 168(4268): 277-280.
[29] EUCKEN A. The heat conductivity of certain crystals at low temperatures[J]. Phys Zs, 1911, 12: 1005.
[30] BERMAN R, SIMON F E, ZIMAN J M. The thermal conductivity of diamond at low temperatures[J]. Proceedings of the Royal Society of London Series A Mathematical and Physical Sciences, 1953, 220(1141): 171-183.
[31] SLACK G A. Nonmetallic crystals with high thermal conductivity[J]. Journal of Physics and Chemistry of Solids, 1973, 34(2): 321-335.
[32] SLACK G A. The thermal conductivity of nonmetallic crystals[M]//Solid State Physics. Amsterdam: Elsevier, 1979: 1-71.
[33] TROPF W J, THOMAS M E, HARRIS T J. Properties of crystals and glasses[J]. Handbook of Optics, 1995, 2: 33-61.
[34] 张召,卢文壮,左敦稳.大尺寸单晶金刚石制备的研究进展[J].人工晶体学报,2017,46(12):2417-2421+2437.
ZHANG Z, LU W Z, ZUO D W. Progress research on deposition of large size single crystal diamond[J]. Journal of Synthetic Crystals, 2017, 46(12): 2417-2421+2437(in Chinese).
[35] KANG J S, LI M, WU H, et al. Experimental observation of high thermal conductivity in boron arsenide[J]. Science, 2018, 361(6402): 575-578.
[36] KU S M. Preparation and properties of boron arsenides and boron arsenide-gallium arsenide mixed crystals[J]. Journal of the Electrochemical Society, 1966, 113(8): 813.
[37] TIAN F, SONG B, CHEN X, et al. Unusual high thermal conductivity in boron arsenide bulk crystals[J]. Science, 2018, 361(6402): 582-585.
[38] LINDSAY L, BROIDO D A, REINECKE T L. First-principles determination of ultrahigh thermal conductivity of boron arsenide: a competitor for diamond? [J]. Physical Review Letters, 2013, 111(2): 025901.
[39] WATANABE K, TANIGUCHI T, KANDA H. Ultraviolet luminescence spectra of boron nitride single crystals grown under high pressure and high temperature[J]. Physica Status Solidi (a), 2004, 201(11): 2561-2565.
[40] TANIGUCHI T, YAMAOKA S. Spontaneous nucleation of cubic boron nitride single crystal by temperature gradient method under high pressure[J]. Journal of Crystal Growth, 2001, 222(3): 549-557.
[41] SLACK G A, SCHOWALTER L J, MORELLI D, et al. Some effects of oxygen impurities on AlN and GaN[J]. Journal of Crystal Growth, 2002, 246(3/4): 287-298.
[42] WANG Q K, LEI D, HE G D, et al. Characterization of 60 mm AlN single crystal wafers grown by the physical vapor transport method[J]. Physica Status Solidi (a), 2019, 216(16): 1900118.
[43] MUTH J F, BROWN J D, et al. Absorption coefficient and refractive index of GaN, AlN and AlGaN alloys[J]. MRS Internet Journal of Nitride Semiconductor Research, 1999, 4(S1): 502-507.
[44] YOSHIDA T, IMANISHI M, KITAMURA T, et al. Development of GaN substrate with a large diameter and small orientation deviationn[J]. Physica Status Solidi B, 2017, 254(8): 1600671.
[45] KANG J S, WU H, HU Y J. Thermal properties and phonon spectral characterization of synthetic boron phosphide for high thermal conductivity applications[J]. Nano Letters, 2017, 17(12): 7507-7514.
[46] ZHENG Q Y, LI S, LI C H, et al. High thermal conductivity in isotopically enriched cubic boron phosphide[J]. Advanced Functional Materials, 2018, 28(43): 1805116.
[47] NWAGWU U. Flux growth and characteristics of cubic boron phosphide[D]. Manhattan, Kansas: Kansas State University, 2013: 37-59.
[48] KUMASHIRO Y, YAO T, GONDA S. Crystal growth of boron phosphide by high pressure flux method[J]. Journal of Crystal Growth, 1984, 70(1/2): 515-518.
[49] WEBER M J. Handbook of optical materials[M]. Boca Raton, FL: CRC Press, 2002
[50] RICHMAN D. Vapor phase growth and properties of aluminum phosphide[J]. Journal of the Electrochemical Society, 2019, 115(9): 945.
[51] MONEMAR B. Determination of band gap and refractive index of AIP from optical absorption[J]. Solid State Communications, 1970, 8(16): 1295-1298.
[52] GOLDBERG Y A. Gallium phosphide (Gap)[M]//LEVINSHTEIN M, RUMYANTSEV S, SHUR M. Handbook Series on Semiconductor Parameters. Singapore: World Scientific Pub Co Inc, 1996: 104-124.
[53] YOUNG M, LIU X, ZHANG D, et al. Latest developments in vertical gradient freeze (VGF) technology: GaAs, InP, and GaP[J]. Materials Science and Engineering: B, 1999, 66(1/2/3): 1-6.
[54] MARINOPOULOS A G, VILÃO R C, VIEIRA R B L, et al. Defect levels and hyperfine constants of hydrogen in beryllium oxide from hybrid-functional calculations and muonium spectroscopy[J]. Philosophical Magazine, 2017, 97(24): 2108-2128.
[55] MASLOV V A, RYLOV G M, MAZURENKO V G, et al. Conditions of growth, structure, spectral and luminescent properties of crystals BeO[C]//Proceedings of the 6th International Conference on crystals growth, Institute of Crystallography, Moscow. 1980: 268-269.
[56] VLASKINA S I, SHIN D H. 6H to 3C polytype transformation in silicon carbide[J]. Japanese Journal of Applied Physics, 1999, 38(Part 2, No. 1A/B): L27-L29.
[57] POWELL A R, SUMAKERIS J J, KHLEBNIKOV Y, et al. Bulk growth of large area SiC crystals[C]//Materials Science Forum. Trans Tech Publications Ltd, 2016, 858: 5-10.
[58] 戴小林,常青.450 mm IC级硅单晶的制备[J].中国材料进展,2010,29(10):21-24+58.
DAI X L, CHANG Q. Growth of 450 mm Cz Si single crystal of IC grade[J]. Materials China, 2010, 29(10): 21-24+58(in Chinese).
[59] BORMASHOV V S, TARELKIN S A, BUGA S G, et al. Electrical properties of the high quality boron-doped synthetic single-crystal diamonds grown by the temperature gradient method[J]. Diamond and Related Materials, 2013, 35: 19-23.
[60] VINS V G, PESTRYAKOV E V. Color centers in diamond crystals: their potential use in tunable and femtosecond lasers[J]. Diamond and Related Materials, 2006, 15(4/5/6/7/8): 569-571.
[61] GROTJOHN T A, TRAN D T, YARAN M K, et al. Heavy phosphorus doping by epitaxial growth on the (111) diamond surface[J]. Diamond and Related Materials, 2014, 44: 129-133.
[62] NISHITANI-GAMO M, YASU E J, XIAO C Y, et al. Sulfur-doped homoepitaxial (001) diamond with n-type semiconductive properties[J]. Diamond and Related Materials, 2000, 9(3/4/5/6): 941-947.
[63] EKIMOV E A, KONDRIN M V. Vacancy-impurity centers in diamond: prospects for synthesis and applications[J]. Physics-Uspekhi, 2017, 60(6): 539-558.
[64] TCHERNIJ S D, HERZIG T, FORNERIS J, et al. Single-photon-emitting optical centers in diamond fabricated upon Sn implantation[J]. ACS Photonics, 2017, 4(10): 2580-2586.
[65] JAMISON K D, SCHMIDT H K. Doped diamond laser: US5504767[P]. 1996-04-02.
[66] SHIOMI H, NISHIBAYASHI Y, SHIKATA S I. Semiconductor lasers comprising rare earth metal-doped diamond: US5812573[P]. 1998-09-22.
[67] RAND S C, DESHAZER L G. Visible color-center laser in diamond[J]. Optics Letters, 1985, 10(10): 481-483.
[68] WILLIAMS R J, ONDREJ K, BAI Z X, et al. High power diamond Raman lasers[J]. IEEE Journal of Selected Topics in Quantum Electronics, 2018, 24(5): 1-14.
[69] TAIROV Y M, KHLEBNIKOV I I, TSVETKOV V F. Investigation of silicon carbide single crystals doped with scandium[J]. Physica Status Solidi (a), 1974, 25(1): 349-357.
[70] KOZANECKI A, JANTSCH W, LANZERSTORFER S, et al. 1.54 μm Luminescence in Er and Er+O Implanted 6H SiC[C]//Materials Science Forum. Trans Tech Publications Ltd, 1997, 258: 1545-1550.
[71] WILSON R G, SCHWARTZ R N, ABERNATHY C R, et al. 1.54-μm photoluminescence from Er-implanted GaN and AlN[J]. Applied Physics Letters, 1994, 65(8): 992-994.
[72] MARTIN R. Rare Earth doped Ⅲ-nitrides for optoelectronic and spintronic applications: rare earth doped Ⅲ-nitrides for optoelectronic and spintronic applications[M]. Dordrecht: Springer, 2010: 189-219.
[73] MEZDROGINA M M, DANILOVSKII E Y, KUZ’MIN R V. Emission from rare-earth ions in GaN wurtzite crystals[J]. Inorganic Materials, 2011, 47(13): 1450-1469.
[74] LORENZ K, ALVES E, MONTEIRO T, et al. Optical doping of AlN by rare earth implantation[J]. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions With Materials and Atoms, 2006, 242(1/2): 307-310.
[75] YANG S, EVANS S M, HALLIBURTON L E, et al. Electron paramagnetic resonance of Er³⁺ ions in aluminum nitride[J]. Journal of Applied Physics, 2009, 105(2): 023714.
[76] PARK J H, STECKL A J. Laser action in Eu-doped GaN thin-film cavity at room temperature[J]. Applied Physics Letters, 2004, 85(20): 4588-4590.
[77] PARK J H, STECKL A J. Site specific Eu³⁺ stimulated emission in GaN host[J]. Applied Physics Letters, 2006, 88(1): 011111.
[78] USOV I, ARENDT P N. Method for implantation of high dopant concentrations in wide band gap materials: US20060286784[P]. 2006-12-21.
[79] ISHIKAWA R, LUPINI A R, OBA F, et al. Atomic structure of luminescent centers in high-efficiency Ce-doped w-AlN single crystal[J]. Scientific Reports, 2014, 4: 3778.
[80] SLACK G A, TANZILLI R A, POHL R O, et al. The intrinsic thermal conductivity of AIN[J]. Journal of Physics and Chemistry of Solids, 1987, 48(7): 641-647.
[81] AGGARWAL R L, RIPIN D J, OCHOA J R, et al. Measurement of thermo-optic properties of Y₃Al₅O₁₂, Lu₃Al₅O₁₂, YAIO₃, LiYF₄, LiLuF₄, BaY₂F₈, KGd(WO₄)₂, and KY(WO₄)₂ laser crystals in the 80-300K temperature range[J]. Journal of Applied Physics, 2005, 98(10): 103514.
[82] GAUMÉ R, VIANA B, VIVIEN D, et al. A simple model for the prediction of thermal conductivity in pure and doped insulating crystals[J]. Applied Physics Letters, 2003, 83(7): 1355-1357.
[83] SU L B, GUO X S, JIANG D P, et al. Highly-efficient mid-infrared CW laser operation in a lightly-doped 3at.% Er∶SrF₂ single crystal[J]. Optics Express, 2018, 26(5): 5558-5563.
[84] 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, 2018, 43(8): 1726-1729.
[85] 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, 2018, 43(17): 4300-4303.
[86] WEI L, KUO P K, THOMAS R L, et al. Thermal conductivity of isotopically modified single crystal diamond[J]. Physical Review Letters, 1993, 70(24): 3764-3767.
[87] OZHOGIN V I, INYUSHKIN A V, TALDENKOV A N, et al. Isotope effect in the thermal conductivity of germanium single crystals[J]. Journal of Experimental and Theoretical Physics Letters, 1996, 63(6): 490-494.
[88] INYUSHKIN A V, TALDENKOV A N, YU YAKUBOVSKY A, et al. Thermal conductivity of isotopically enriched 71 crystal[J]. Semiconductor Science and Technology, 2003, 18(7): 685-688.
[89] KREMER R K, GRAF K, CARDONA M, et al. Thermal conductivity of isotopically enriched ²⁸Si: revisited[J]. Solid State Communications, 2004, 131(8): 499-503.
[90] CHEN K, SONG B, RAVICHANDRAN N K, et al. Ultrahigh thermal conductivity in isotope-enriched cubic boron nitride[J]. Science, 2020, 367(6477): 555-559.
[91] JULIAN C L. Theory of heat conduction in rare-gas crystals[J]. Physical Review, 1965, 137(1A): A128-A137.
[92] BROIDO D A, MALORNY M, BIRNER G, et al. Intrinsic lattice thermal conductivity of semiconductors from first principles[J]. Applied Physics Letters, 2007, 91(23): 231922.
[93] LI S, ZHENG Q Y, LV Y C, et al. High thermal conductivity in cubic boron arsenide crystals[J]. Science, 2018, 361(6402): 579-581.
[94] QIAN X, ZHOU J W, CHEN G. Phonon-engineered extreme thermal conductivity materials[J]. Nature Materials, 2021, 20(9): 1188-1202.