Research Progress of Single-Crystal Optical Fiber Sensing Technology for Extreme Environments

doi:10.16553/j.cnki.issn1000-985x.2026.0059

Abstract

Abstract: Extreme environments， including aerospace， nuclear reactors， and deep-earth exploration， impose stringent requirements on reliable sensing technologies. Traditional silica-based optical fibers are prone to structural degradation under high temperatures and intense radiation. In contrast， single-crystal optical fibers， represented by sapphire and yttrium aluminum garnet （YAG）， have attracted attention as promising alternative media due to their excellent physical and chemical stability. This paper reviews the research progress of single-crystal optical fiber sensing technologies tailored for extreme environments. It summarizes the evolution of mainstream growth techniques for single-crystal optical fibers， such as laser-heated pedestal growth and the micro-pulling-down method， and discusses the improvements in mode control achieved through the development of cladding structures. Furthermore， it provides an in-depth analysis of the applications of in situ microstructure processing technologies—typified by femtosecond laser plane-by-plane inscription—in the fabrication of sensing components like high-quality fiber Bragg gratings. The paper also reviews practical monitoring applications of single-crystal optical fiber sensors under extreme operating conditions， including ultra-high temperatures， intense radiation， and high pressures. Finally， it outlines the future development trajectories of single-crystal optical fiber sensing technology， particularly focusing on material defect suppression， the preparation of specialized claddings， and anti-interference in signal demodulation.

Key words: single-crystal optical fiber; optical fiber sensing; crystal growth; femtosecond laser micromachining; fiber Bragg grating; extreme environment

CLC Number:

O436

LUO Zheyu, TONG Laiyuan, ZHANG Zhenrong, HUANG Junjia, YU Yang. Research Progress of Single-Crystal Optical Fiber Sensing Technology for Extreme Environments[J]. Journal of Synthetic Crystals, 2026, 55(7): 1060-1083.

Figures/Tables 24

Table 1 Performance parameters of single-crystal optical fiber host materials

Crystal	Crystal structure	Melting point/℃	Refractive index	Thermal expansion coefficient/（10^-6 K^-1）	Characteristic
Al₂O₃	三方晶系	2 045	1.760~1.768	5.3~7.7	高温强度高；抗辐射损伤能力强；存在本征双折射
YAG	立方晶系	1 970	1.82~1.83	7.8	结构各向同性；稀土离子掺杂适应性强
Spinel	立方晶系	2 135	1.71~1.72	7.4~7.9	透光波段宽；抗热震性好；抗中子辐照能力强
ZrO₂	立方晶系	2 780	2.15~2.18	10.3	熔点高；热化学稳定性好；适用于超高温及耐火环境
LiNbO₃	三方晶系	1 250	2.214~2.300	4.1~15.4	电光与压电效应强；适用于极端电磁场传感
LuAG	立方晶系	2 020	1.83~1.84	8.8	晶体密度大；对X射线/伽马射线阻止能力强

Fig.1 （a） Schematic diagram of the sensor；（b） side view micrograph of the sapphire capillary；（c） micrograph of the through hole；（d） photograph of the sensor；（e） encapsulation of the sensor［28］

Fig.2 Schematic of the sensing probe［29］

Fig.3 （a） Scheme diagram of the partly crystallization-sapphire derived fiber FPI；（b） microscopic image of the sensor［40］

Fig.4 （a） Experimental setup for sealing the sensor with inert gas （GPC： gas pressure controller； PU： polyurethane）；（b） scheme for the demodulation system［41］

Fig.5 Schematic diagram （a） and equipment photo （b） of the micro-pulling-down （μ-PD） technique［53］

Fig.6 Schematic representation of the LHPG technique［54］

Fig.7 Fluctuations in laser power and single-crystal optical ?ber diameter［55］

Fig.8 Far-field measurements were taken at varying diameters using laser wavelengths of 532， 783， and 983?nm. Low-order modes became visible at a sapphire fiber diameter of 6.5?μm， and measurements were consistent when the light injection angle was altered by 15°［57］

Fig.9 Transmission end view of another clad crystalline sapphire （Ti∶Al2O3/Al2O3） fiber grown using the hybrid growth method［58］

Fig.10 Microscope images of the fabricated SFBG［67］. （a） Cross-sectional view；（b） top view；（c） lateral view

Table 2 Performance comparison of femtosecond laser inscription techniques across different spatial dimensions

Inscription technique

Typical

reflectivity

Typical linewidth

（3 dB bandwidth）

Processing time and

inscription efficiency

Applications and technical characteristic

截面覆盖高；模式对称性好；适合大芯径/多模光纤

Fig.11 Interferogram before and after rapid heat treatment［68］

Fig.12 Design and picture of the sensor packaging［75］

Fig.13 Provides a schematic representation of the fs-laser system and the proposed SFBGs fabricated through the line-by-line scanning method， the red dashed boxes within the figure draw attention to micrographs showcasing the splice joint between the MMF and sapphire fiber， as well as featuring 30°polished end facet of the sapphire fiber［78］

Fig.14 Schematic diagram of the temperature measurement system［80］

Fig.15 Delay data and waveforms at different temperatures［80］

Fig.16 （a） Schematic diagram of all sapphire FP sensor heads［81］；（b） schematic diagram of the sapphire based fiber-optic EFPI sensor［82］

Fig.17 （a） Schematic diagram of the MFPTP；（b） schematic of beam propagation through a microsphere-lensed fiber；（c） model of dual-FP-cavity deflection for temperature and pressure［83］

Fig.18 Sapphire optical fiber vibration sensor［84］. （a） Configuration；（b） physical layout；（c） ceramic base；（d） ceramic plate；（e） ceramic assembly

Fig.19 System architecture of proposed high temperature Raman DTS［85］

Fig.20 As-grown LuAG∶Ce-LuAG SSCF with detection-transmission integrated performance［88］

Fig.21 （a） Integrated radioluminescence peaks intensity of STE+F++AD and Ce3+ at different positions；（b） integrated radioluminescence peak intensity in the initial region； “U-R”， uniform region；“I-R”， initial region； “T-R”， transmission region［88］

Table 3 Performance comparison of single-crystal optical fiber sensors in extreme environments

Research team	Sensor type and core mechanism	Maximum operating/Calibration temperature	Sensitivity or accuracy of parameters （Strain/pressure/acceleration， etc.）	Continuous operation/stability test duration
Li等^［72］	SFBG斜端面降反射	1 100 ℃	1.6 $p m$ / $μ ε$ （1 100 ℃下）	4 h
He等^［73］	充Ar封装SFBG+梯度退火	1 800 ℃	41.2 $p m$ /℃（1 800 ℃下）	1 600 ℃稳定20 h
Yang等^［75］	WDM-SFBG阵列+管套管封装	1 000 ℃	26.3 $p m$ /℃	燃煤锅炉42 d；燃气锅炉48 d
Alla等^［76］	级联SFBG+电子多模扰相	1 612 ℃	热漂移在±2 ℃以内	陶瓷炉22 h；钢水浸入30 min
Mumtaz等^［77］	三级联SFBG+多模扰相	1 600 ℃	温度波动±1 ℃	1 600 ℃连续24 h
Mumtaz等^［78］	重合a-SFBG/p-SFBG双参量解耦	1 600 ℃	a-SFBG：0.4 $p m$ / $μ ε$ ， p-SFBG：1.8 $p m$ / $μ ε$	24 h（承受1 000 $μ ε$ 与1 600 ℃高温双重施加）
Eisermann等^［79］	S-FBG/热辐射/热电偶混合传感	1 600 ℃	长期服役后漂移小于0.5 ℃	超3周（连续约500 h），覆盖25个工业硅凝固生产周期
Wang等^［80］	多节点蓝宝石超声温度传感	1 600 ℃（标定）；740 ℃（铝液）	动态测温误差小于1 ℃	55.65 s达热平衡，未明确长周期具体时长
Shao等^［81］	全蓝宝石FP压力传感器	1 200 ℃	约25 $n m$ /MPa；非线性度0.96%F.S.	稳定运行
Liao等^［82］	双FP腔EFPI+温度补偿	1 500 ℃	压力精度0.86%F.S.	重复性误差1.73%F.S.；未给出长时数据
Liu等^［83］	MgO双FP复合腔+温度解耦	800 ℃	约0.20 $μ m$ /MPa压力测量精度 2.01%F.S.	0.5 MPa静态标定；未给出长效数据
Cui等^［84］	蓝宝石光纤高温振动传感	1 500 ℃	20.91 $n m$ /g（室温）15.6 $n m$ /g（600 ℃）	0~10 g线性标定；未测长效
Liu等^［85］	YAG拉曼DTS+2D图像复原/NLM去噪算法	1 400 ℃	单毫秒平均温度标准差降至7.89 ℃；1 s采集分辨率0.62 ℃	毫秒级动态响应验证

Table 3 Performance comparison of single-crystal optical fiber sensors in extreme environments

Research team	Sensor type and core mechanism	Maximum operating/Calibration temperature	Sensitivity or accuracy of parameters （Strain/pressure/acceleration， etc.）	Continuous operation/stability test duration
Li等^［72］	SFBG斜端面降反射	1 100 ℃	1.6 $p m$ / $μ ε$ （1 100 ℃下）	4 h
He等^［73］	充Ar封装SFBG+梯度退火	1 800 ℃	41.2 $p m$ /℃（1 800 ℃下）	1 600 ℃稳定20 h
Yang等^［75］	WDM-SFBG阵列+管套管封装	1 000 ℃	26.3 $p m$ /℃	燃煤锅炉42 d；燃气锅炉48 d
Alla等^［76］	级联SFBG+电子多模扰相	1 612 ℃	热漂移在±2 ℃以内	陶瓷炉22 h；钢水浸入30 min
Mumtaz等^［77］	三级联SFBG+多模扰相	1 600 ℃	温度波动±1 ℃	1 600 ℃连续24 h
Mumtaz等^［78］	重合a-SFBG/p-SFBG双参量解耦	1 600 ℃	a-SFBG：0.4 $p m$ / $μ ε$ ， p-SFBG：1.8 $p m$ / $μ ε$	24 h（承受1 000 $μ ε$ 与1 600 ℃高温双重施加）
Eisermann等^［79］	S-FBG/热辐射/热电偶混合传感	1 600 ℃	长期服役后漂移小于0.5 ℃	超3周（连续约500 h），覆盖25个工业硅凝固生产周期
Wang等^［80］	多节点蓝宝石超声温度传感	1 600 ℃（标定）；740 ℃（铝液）	动态测温误差小于1 ℃	55.65 s达热平衡，未明确长周期具体时长
Shao等^［81］	全蓝宝石FP压力传感器	1 200 ℃	约25 $n m$ /MPa；非线性度0.96%F.S.	稳定运行
Liao等^［82］	双FP腔EFPI+温度补偿	1 500 ℃	压力精度0.86%F.S.	重复性误差1.73%F.S.；未给出长时数据
Liu等^［83］	MgO双FP复合腔+温度解耦	800 ℃	约0.20 $μ m$ /MPa压力测量精度 2.01%F.S.	0.5 MPa静态标定；未给出长效数据
Cui等^［84］	蓝宝石光纤高温振动传感	1 500 ℃	20.91 $n m$ /g（室温）15.6 $n m$ /g（600 ℃）	0~10 g线性标定；未测长效
Liu等^［85］	YAG拉曼DTS+2D图像复原/NLM去噪算法	1 400 ℃	单毫秒平均温度标准差降至7.89 ℃；1 s采集分辨率0.62 ℃	毫秒级动态响应验证

References 88

[1]	ZHANG Q W， LIU Y， LI H F， et al. A review of SiC sensor applications in high-temperature and radiation extreme environments［J］. Sensors， 2024， 24（23）： 7731. DOI URL
[2]	ROVERA A， TANCAU A， BOETTI N， et al. Fiber optic sensors for harsh and high radiation environments in aerospace applications［J］. Sensors， 2023， 23（5）： 2512. DOI URL
[3]	杨杭洲，刘　鑫，南朋玉，等. 光纤高温应变传感器研究进展［J］. 光子学报， 2022， 51（10）： 1006002.
	YANG H Z， LIU X， NAN P Y， et al. Progress in research of optical fiber high temperature and strain sensor［J］. Acta Photonica Sinica， 2022， 51（10）： 1006002 （in Chinese）. DOI URL
[4]	BORZYCKI K， JAWORSKI M， KOSSEK T. High temperature effects in fused silica optical fibers［J］. Journal of Telecommunictions and Information Technology， 2021， 3（2021）： 56-71.
[5]	BAO Y， CHEN G D. High-temperature measurement with Brillouin optical time domain analysis of an annealed fused-silica single-mode fiber［J］. Optics Letters， 2016， 41（14）： 3177-3180. DOI PMID
[6]	WARREN-SMITH S C， NGUYEN L V， EBENDORFF-HEIDEPRIEM H， et al. High temperature sensing with single material silica optical fibers［C/OL］//CHUNG Y， JIN W， LEE B， et al. 25th International Conference on Optical Fiber Sensors. Jeju， Korea， Republic of， 2017： 103233M ［2026-04-07］. http：//proceedings.spiedigitallibrary.org/proceeding.aspx doi=10.1117/12.2265205.
[7]	ONO M， AOYAMA S， FUJINAMI M， et al. Significant suppression of Rayleigh scattering loss in silica glass formed by the compression of its melted phase［J］. Optics Express， 2018， 26（7）： 7942. DOI PMID
[8]	MAXWELL G， PONTING B， GEBREMICHAEL E， et al. Advances in single-crystal fibers and thin rods grown by laser heated pedestal growth［J］. Crystals， 2017， 7（1）： 12. DOI URL
[9]	WANG T， ZHANG J， ZHANG N， et al. Single crystal fibers： diversified functional crystal material［J］. Advanced Fiber Materials， 2019， 1（3）： 163-187. DOI
[10]	BURIC M， LIU B， HUANG S， et al. Modified single crystal fibers for distributed sensing applications［C/OL］//BALDWIN C S， PICKRELL G， DU H H. SPIE Commercial + Scientific Sensing and Imaging. Anaheim， California， United States， 2017： 102080C ［2026-04-07］. http：//proceedings.spiedigitallibrary.org/proceeding.aspx doi=10.1117/12.2262992.
[11]	KEFER S， ZETTL J， ESEN C， et al. Femtosecond laser-based micromachining of rotational-symmetric sapphire workpieces［J］. Materials， 2022， 15（18）： 6233. DOI URL
[12]	LIU H， JIA P G， SU C X， et al. High-temperature fiber-optic Fabry-Perot vibration sensor based on single-crystal sapphire［J］. Sensors， 2023， 23（10）： 4952. DOI URL
[13]	HE J， LI Z D， XU X Z， et al. High-temperature strain sensor based on sapphire fiber Bragg grating［J］. Optics Letters， 2024， 49（3）： 446-449. DOI PMID
[14]	GUO Q， JIA Z X， PAN X P， et al. Sapphire-derived fiber Bragg gratings for high temperature sensing［J］. Crystals， 2021， 11（8）： 946. DOI URL
[15]	WANG M H， SALTER P S， PAYNE F P， et al. Single-mode sapphire fiber Bragg grating［J］. Optics Express， 2022， 30（9）： 15482. DOI PMID
[16]	SHI G N， SHURTZ R， PICKRELL G， et al. Point-by-point inscribed sapphire parallel fiber Bragg gratings in a fully multimode system for multiplexed high-temperature sensing［J］. Optics Letters， 2022， 47（18）： 4724-4727. DOI PMID
[17]	XIAO H， DENG J D， PICKRELL G， et al. Single-crystal sapphire fiber-based strain sensor for high-temperature applications［J］. Journal of Lightwave Technology， 2003， 21（10）： 2276-2283. DOI URL
[18]	MIHAILOV S J， GROBNIC D， SMELSER C W. High-temperature multiparameter sensor based on sapphire fiber Bragg gratings［J］. Optics Letters， 2010， 35（16）： 2810-2812. DOI PMID
[19]	SHEN Y H， TONG L M， WANG Y Q， et al. Sapphire-fiber thermometer ranging from 20 to 1800 ℃［J］. Applied Optics， 1999， 38（7）： 1139-1143. DOI URL
[20]	YE L H， ZHANG J F， SHI Y. Growth and characteristics of Cr³⁺∶YAG crystal fiber for fluorescence decay temperature sensor［J］. Review of Scientific Instruments， 2006， 77（5）： 054901.
[21]	GUO Y Q， XIA W， HU Z Z， et al. High-temperature sensor instrumentation with a thin-film-based sapphire fiber［J］. Applied Optics， 2017， 56（8）： 2068-2073. DOI URL
[22]	WANG A B， WANG G Z， MURPHY K A， et al. Birefringence-balanced polarimetric optical fiber sensor for high-temperature measurements［J］. Optics Letters， 1992， 17（19）： 1391-1393. PMID
[23]	PENG W. High-temperature fiber optic cubic-zirconia pressure sensor［J］. Optical Engineering， 2005， 44（12）： 124402. DOI URL
[24]	WU D， KABIR M， CHOU K T， et al. Growth of multifunctional electro-optic Yb∶LiNbO₃ crystalline fibers by laser heated pedestal growth （LHPG） method［C/OL］//YIN S， GUO R. Photonic Fiber and Crystal Devices： Advances in Materials and Innovations in Device Applications XVIII. San Diego， United States： SPIE， 2024： 10 ［2026-02-09］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/13140/3027561/Growth-of-multifunctional-electro-optic-Yb-LiNbO3-crystalline-fibers-by/10.1117/12.3027561.full.
[25]	CHEN N， ZHANG X B， ZHANG Q， et al. Ultrasensitive all-fiber microphone with in-line beam and 45° tilted optical fiber fabricated by laser micromachining［J］. Optics Express， 2025， 33（26）： 54257. DOI URL
[26]	GAO S， LIU Y， YANG J， et al. Ultracompact Fabry-Perot interferometer based on femtosecond laser-assisted wet etching for high-temperature sensing［J］. Optics Express， 2025， 33（12）： 24350. DOI URL
[27]	ZHU Y Z， WANG A B. Surface-mount sapphire interferometric temperature sensor［J］. Applied Optics， 2006， 45（24）： 6071-6076. PMID
[28]	ZHANG Y T， JIANG Y， YANG S W， et al. All-sapphire fiber-optic sensor for the simultaneous measurement of ultra-high temperature and high pressure［J］. Optics Express， 2024， 32（8）： 14826. DOI PMID
[29]	ZHAO S， JIANG Y， DENG H， et al. High sensitivity all-sapphire fiber diaphragm-based extrinsic Fabry-Perot interferometric pressure sensor for ultra-high temperature environments［J］. Optics Express， 2025， 33（18）： 37322. DOI URL
[30]	GUO K K， WU H， LIANG Y H， et al. Highly birefringent FBG based on femtosecond laser-induced cladding stress region for temperature and strain decoupling［J］. Photonics， 2025， 12（5）： 502. DOI URL
[31]	ACETI P， CALERVO L， BETTINI P， et al. Measurement and decoupling of hygrothermal-mechanical effects with optical fibers： development of a new fiber Bragg grating sensor［J］. Sensors， 2025， 25（4）： 1037. DOI URL
[32]	HUANG Q S， TANG Y， ZHANG Y M， et al. Strain and temperature cross-sensitivity decoupling method via a single glass fiber-reinforced polymer encapsulated chirped fiber Bragg grating［J］. Optics Express， 2026， 34（2）： 2901. DOI URL
[33]	WANG Z C， XU W J， WANG L N， et al. High-temperature stability and demodulation techniques analysis of sapphire fiber Bragg grating sensor［J］. Journal of Lightwave Technology， 2025， 43（5）： 2312-2320. DOI URL
[34]	MIHAILOV S J. Fiber Bragg grating sensors for harsh environments［J］. Sensors， 2012， 12（2）： 1898-1918. DOI PMID
[35]	HE J， LI Z， QIN Z， et al. Etched single-crystal sapphire fiber Bragg gratings for simultaneous temperature and strain sensing at 1 500 ℃［C/OL］//LOPEZ-AMO SAINZ M， SANTOS J L， SUN T. 29th International Conference on Optical Fiber Sensors. Porto， Portugal： SPIE， 2025： 487 ［2026-03-07］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/13639/3062888/Etched-single-crystal-sapphire-fiber-Bragg-gratings-for-simultaneous-temperature/10.1117/12.3062888.full.
[36]	MA S N， XU Y P， PANG Y X， et al. Optical fiber sensors for high-temperature monitoring： a review［J］. Sensors， 2022， 22（15）： 5722. DOI URL
[37]	刘铁根，于　迅，王　双，等. 高温环境下光纤法布里-珀罗微腔传感技术研究进展［J］. 激光与光电子学进展， 2021， 58（13）： 1306002.
	LIU T G， YU X， WANG S， et al. Fiber-optic Fabry-Perot sensing technology in high-temperature environments： a review［J］. Laser & Optoelectronics Progress， 2021， 58（13）： 1306002 （in Chinese）.
[38]	ZHU K S， ZHOU H L， QIU J R， et al. Optical temperature sensing characteristics of Sm³⁺ doped YAG single crystal fiber based on luminescence emission［J］. Journal of Alloys and Compounds， 2022， 890： 161844. DOI URL
[39]	ZHU K S， ZHOU H L， WANG J， et al. Optical temperature sensing characteristics of Yb³⁺/Nd³⁺ co-doped YAG single crystal fiber based on up-conversion luminescence［J］. Journal of Luminescence， 2024， 267： 120347. DOI URL
[40]	ZHANG P H， ZHANG L， MOURELATOS Z P， et al. Crystallization-sapphire-derived-fiber-based Fabry-Perot interferometer for refractive index and high-temperature measurement［J］. Applied Optics， 2018， 57（30）： 9016-9021. DOI URL
[41]	CHEN X， ZHANG J D， JIANG J F， et al. Direct-bonding sapphire fiber microcavity sensor for ultra-high-temperature measurement［J］. Journal of Lightwave Technology， 2026， 44（5）： 1993-2001. DOI URL
[42]	LI R， LIU X M， CHEN Y R， et al. Ultra-high sensitivity microwave-photonic sapphire fiber Fabry-Perot interferometry based on the Vernier effect［J］. Optics Express， 2023， 31（15）： 25047. DOI PMID
[43]	MUMTAZ F， TEKLE H， ZHANG B， et al. Distributed sapphire fiber sensors for steel-making industrial applications［C/OL］//SANDERS G A， LIEBERMAN R A， BURIC M P. Optical Waveguide and Laser Sensors III. National Harbor， United States： SPIE， 2024： 6［2026-03-11］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/13044/3014035/Distributed-sapphire-fiber-sensors-for-steel-making-industrial-applications/10.1117/12.3014035.full.
[44]	TAN Q M， UNIVERSITY S， LI Z D， et al. Sapphire fiber Bragg gratings array demodulated with the multi-peak auto-tracking algorithm for quasi-distributed high-temperature measurement［J］. Optics Express， 2025， 33（1）： 414. DOI PMID
[45]	WUENSCHELL J K， BERA S， LIM G， et al. Development of a single crystal fiber probe for Raman distributed temperature sensing above 1 000 ℃［C/OL］//SOSKIND Y， BUSSE L E. Photonic Instrumentation Engineering IX. San Francisco， United States： SPIE， 2022： 45 ［2026-03-11］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/12008/2610352/Development-of-a-single-crystal-fiber-probe-for-Raman-distributed/10.1117/12.2610352.full.
[46]	LIU X， CAI K D， GUO S Q， et al. Physical model-assisted hybrid neural network enabling high spatial resolution distributed high-temperature sensing with single-crystal fiber［J］. IEEE Transactions on Instrumentation and Measurement， 2025， 74： 7009912.
[47]	XU Y， WANG R L， XUE X H， et al. High spatial resolution Raman distributed fiber sensing based on neural network dispersion compensation［J］. Optics Express， 2025， 33（15）： 31139. DOI URL
[48]	YAN Z H， DU B， LI Z D， et al. High-resolution Raman-OTDR distributed temperature sensors based on fast-non local means denoising algorithm［J］. Journal of Lightwave Technology， 2025， 43（19）： 9465-9473. DOI URL
[49]	NEHARI A， DUFFAR T， GHEZAL E A， et al. Chemical segregation of titanium in sapphire single crystals grown by micro-pulling-down technique： analytical model and experiments［J］. Crystal Growth & Design， 2014， 14（12）： 6492-6496. DOI URL
[50]	BERA S， LIU B， WUENSCHELL J K， et al. Fabrication and evaluation of sapphire fiber cladding via magnesium aluminate spinel sol-gel based approaches［C/OL］//SANDERS G A， LIEBERMAN R A， SCHEEL I U. Fiber Optic Sensors and Applications XVI. Baltimore， United States： SPIE， 2019： 19 ［2026-04-04］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/11000/2518506/Fabrication-and-evaluation-of-sapphire-fiber-cladding-via-magnesium-aluminate/10.1117/12.2518506.full.
[51]	DING J M， MENG F C， ZHAO X T， et al. All-solid anti-resonant single crystal fibers［J］. Frontiers of Optoelectronics， 2022， 15（1）： 3. DOI
[52]	LIU B， OHODNICKI P R. Fabrication and application of single crystal fiber： review and prospective［J］. Advanced Materials Technologies， 2021， 6（9）： 2100125. DOI URL
[53]	WANG A Y， ZHANG J， YE S， et al. Optimized growth and laser application of Yb∶LuAG single-crystal fibers by micro-pulling-down technique［J］. Crystals， 2021， 11（2）： 78. DOI URL
[54]	CAMPOS R V B， HERNANDES A C， BORISKINA S V， et al. High-performance piezoelectric generator based on a monocrystalline LiNbO₃ fiber［J］. Crystal Growth & Design， 2025， 25（3）： 672-679. DOI URL
[55]	GAO X B， WANG S C， LIU B， et al. Machine learning enhanced single crystal fiber fabrication via laser heated pedestal growth［J］. IEEE Photonics Technology Letters， 2025， 37（18）： 1017-1020. DOI URL
[56]	CHEN H， BURIC M， OHODNICKI P R， et al. Review and perspective： sapphire optical fiber cladding development for harsh environment sensing［J］. Applied Physics Reviews， 2018， 5： 011102.
[57]	HILL C， HOMA D， YU Z H， et al. Single mode air-clad single crystal sapphire optical fiber［J］. Applied Sciences， 2017， 7（5）： 473. DOI URL
[58]	KABIR M A， WU K C， CHOU K T， et al. Hybrid growth of clad crystalline sapphire fibers for ultra-high-temperature （>1500 ℃） fiber optic sensors［J］. Photonics， 2025， 12（4）： 299. DOI URL
[59]	HILL C， HOMA D， LIU B， et al. Submicron diameter single crystal sapphire optical fiber［J］. Materials Letters， 2015， 138： 71-73. DOI URL
[60]	YANG S， HOMA D， PICKRELL G， et al. Fiber Bragg grating fabricated in micro-single-crystal sapphire fiber［J］. Optics Letters， 2018， 43（1）： 62-65. DOI PMID
[61]	WANG T， LIU L， WU Y F， et al. Anisotropic growth and characterizations of large length-diameter ratio sapphire fibers via laser-heated pedestal growth technique［J］. Journal of Crystal Growth， 2023， 620： 127363. DOI URL
[62]	WANG T， GUO Q， ZHANG J， et al. Size-unlimited sapphire single-crystal fiber growth and the anisotropic & size-dependent mechanical and thermometry performance［J］. CrystEngComm， 2024， 26（40）： 5726-5733. DOI URL
[63]	GUO Q， LIU S R， PAN X P， et al. Femtosecond laser inscribed helical sapphire fiber Bragg gratings［J］. Optics Letters， 2021， 46（19）： 4836-4839. DOI PMID
[64]	HE J， XU X， HE J， et al. Single-mode helical sapphire fiber Bragg grating sensors fabricated by femtosecond laser direct writing technology［C/OL］//LOPEZ-AMO SAINZ M， SANTOS J L， SUN T. 29th International Conference on Optical Fiber Sensors. Porto， Portugal： SPIE， 2025： 479 ［2026-04-04］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/13639/3062877/Single-mode-helical-sapphire-fiber-Bragg-grating-sensors-fabricated-by/10.1117/12.3062877.full.
[65]	MIHAILOV S J， GROBNIC D， HNATOVSKY C， et al. Extreme environment sensing using femtosecond laser-inscribed fiber Bragg gratings［J］. Sensors， 2017， 17（12）： 2909. DOI URL
[66]	XU X Z， HE J， LIAO C R， et al. Sapphire fiber Bragg gratings inscribed with a femtosecond laser line-by-line scanning technique［J］. Optics Letters， 2018， 43（19）： 4562-4565. DOI PMID
[67]	WU J， HE J， XU X， et al. Femtosecond laser plane-by-plane inscription of high-quality fiber Bragg gratings［C/OL］// 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings （ACP/POEM）. Wuhan， China： IEEE， 2023： 1-3 ［2026-02-07］. https：//ieeexplore.ieee.org/document/10369278/.
[68]	MUMTAZ F， TEKLE H， ZHANG B H， et al. Boosting SNR of cascaded FBGs in a sapphire fiber through a rapid heat treatment［J］. Optics Letters， 2023， 48（21）： 5703-5706. DOI PMID
[69]	LIU X， ZHANG Z K， WANG J X， et al. Future development directions of high-temperature strain gauges： a comprehensive review of structure and performance characteristics［J］. Nanoscale Advances， 2025， 7（14）： 4232-4251. DOI URL
[70]	CONTANGELO R， FERRO C G， BAGNASCO A， et al. Preliminary thermo-mechanical evaluation of fiber Bragg grating sensors for structural monitoring： toward application in generation IV nuclear reactors［J］. Micromachines， 2025， 16（11）： 1204. DOI URL
[71]	WILLSCH M， BOSSELMANN T， FLOHR P， et al. Design of fiber optical high temperature sensors for gas turbine monitoring［C/OL］//JONES J D C. 20th International Conference on Optical Fibre Sensors. Edinburgh， United Kingdom， 2009： 75037R ［2026-03-16］. http：//proceedings.spiedigitallibrary.org/proceeding.aspx doi=10.1117/12.835875.
[72]	LI Z， HE J， XU X， et al. A sapphire fiber Bragg grating strain sensor operating in high temperature environment［C/OL］// YANG Y. Fourteenth International Conference on Information Optics and Photonics （CIOP 2023. Xi’an， China： SPIE， 2023： 279 ［2026-03-16］. https：//www.spiedigitallibrary.org/conference-proceedings-of-spie/12935/3008137/A-sapphire-fiber-Bragg-grating-strain-sensor-operating-in-high/10.1117/12.3008137.full.
[73]	HE J， XU X Z， CHEN R X， et al. Femtosecond laser direct writing of fiber Bragg gratings for multiparameter sensing in extreme environments［J］. APL Photonics， 2025， 10（12）： 120902. DOI URL
[74]	HE J， XU X Z， DU B， et al. Stabilized ultra-high-temperature sensors based on inert gas-sealed sapphire fiber Bragg gratings［J］. ACS Applied Materials & Interfaces， 2022， 14（10）： 12359-12366.
[75]	YANG S， HOMA D， HEYL H， et al. Application of sapphire-fiber-Bragg-grating-based multi-point temperature sensor in boilers at a commercial power plant［J］. Sensors， 2019， 19（14）： 3211. DOI URL
[76]	ALLA D R， NEELAKANDAN D P， MUMTAZ F， et al. Cascaded sapphire fiber Bragg gratings inscribed by femtosecond laser for molten steel studies［J］. IEEE Transactions on Instrumentation and Measurement， 2024， 73： 7000608.
[77]	MUMTAZ F， TEKLE H W， ZHANG B H， et al. Distributed sapphire fiber Bragg grating-based thermal profiling of submerged entry nozzles［J］. IEEE Transactions on Instrumentation and Measurement， 2025， 74： 9530112.
[78]	MUMTAZ F， ZHANG B H， DEY K， et al. Discrimination of temperature and strain by characterizing two femtosecond laser-written coincident sapphire fiber Bragg gratings for harsh environment applications［J］. IEEE Transactions on Instrumentation and Measurement， 2025， 74： 7004309.
[79]	EISERMANN R， KRENEK S， HABISREUTHER T， et al. Metrological characterization of a high-temperature hybrid sensor using thermal radiation and calibrated sapphire fiber Bragg grating for process monitoring in harsh environments［J］. Sensors， 2022， 22（3）： 1034. DOI URL
[80]	WANG G， QIAN C Y， SUN P， et al. A liquid metal temperature detection system based on multi-node sapphire fiber sensor［J］. Sensors， 2023， 23（9）： 4318. DOI URL
[81]	SHAO Z Q， WU Y L， WANG S， et al. All-sapphire fiber-optic pressure sensors for extreme harsh environments［J］. Optics Express， 2022， 30（3）： 3665. DOI PMID
[82]	LIAO Y K， LIU J， DAI Y T， et al. Temperature-compensated fiber-optic Fabry-Perot pressure sensor based on sapphire MEMS technology for high temperature environment up to 1 500 ℃［J］. Optics Express， 2025， 33（9）： 19453. DOI URL
[83]	LIU J， ZHANG L， WANG Z Y， et al. Extreme dual-parameter optical fiber sensor composed of MgO Fabry-Perot composite cavities for simultaneous measurement of temperature and pressure［J］. Applied Sciences， 2025， 15（16）： 8891. DOI URL
[84]	CUI Y， JIANG Y， ZHANG Y T， et al. Sapphire optical fiber high-temperature vibration sensor［J］. Optics Express， 2022， 30（2）： 1056. DOI PMID
[85]	LIU X， JIE R M， BERA S， et al. High-speed and high-resolution YAG fiber based distributed high temperature sensing system empowered by a 2D image restoration algorithm［J］. Optics Express， 2023， 31（4）： 6170. DOI PMID
[86]	ZHANG J， XIANG Y D， WANG C， et al. Recent advances in optical fiber enabled radiation sensors［J］. Sensors， 2022， 22（3）： 1126. DOI URL
[87]	PETRIE C M， BIRRI A， BLUE T E. Optical transmission and dimensional stability of single-crystal sapphire after high-dose neutron irradiation at various temperatures up to 688 ℃［J］. Journal of Nuclear Materials， 2022， 559： 153432. DOI URL
[88]	WANG X B， LI X， DENG M X， et al. A couple-free structured LuAG： Ce-LuAG scintillating single crystal fiber grown by a laser-heated pedestal growth method［J］. Crystal Growth & Design， 2024， 24（8）： 3333-3341. DOI URL