The Internet of things (IOT) is a monumental intelligent information infrastructure of the 21st century. Optical fiber sensing technology, signal transmission technology and intelligent information processing technology are the technical basis of IOT. With the advantages of large capacity, long-distance transmission, low energy consumption, and multi-parameter sensing, optical fiber sensing technology has become a new wave of information technology which promotes the application of information technology in all walks of life. The exploration of the physical mechanism and further development of core technologies of optical fiber sensing, such as novel sensing mechanisms, high-quality laser light sources, new types of optical fibers, innovative detection methods, as well as the pump or signal modulation and demodulation methods, have undoubtedly proven to be a fundamental driving force to push the deep development of optical fiber sensing technology. In this regard, Opto-Electronic Engineering launched a special issue on "Key optical fiber sensing technologies and frontiers". The essence of this special issue is to present innovative optical fiber sensing technology and its future development trend based on the review of the core technologies. Hopefully, this special issue will trigger new discoveries for optical fiber sensing technology improvements.
This special issue includes ten reviews and two research papers. The review article "Laser sources for optical fiber sensing" focuses on the high-quality laser source employed in the optical fiber sensing technology, and mainly reviews the development status and the key technologies of narrow-linewidth laser, tunable laser and broadband light source. From the perspective of the demand for new special optical fibers by optical fiber sensing technology, the review article "Progress and prospect of novel specialty fibers for fiber optic sensing" introduces the development progress of specialty optical fibers, the major techniques of specialty fiber fabrication, and the new optical fiber sensing mechanisms derived from specialty fibers. The review article "Hollow-core photonic bandgap fibers: properties and sensing technology" outlines the basic properties of air-core photonic bandgap fiber and various novel sensing technologies developed on this basis. "Advances of key technologies on optical reflectometry with ultra-high spatial resolution" summarized the research status on state-of-art optical reflectometry technologies and reviewed the advances of key technologies on optical reflectometry with ultra-high spatial resolution and long measurement range, and finally introduces several innovative methods to improve the sensing performance. “Advances of key technologies in long-range distributed Brillouin optical fiber sensing” discussed several long-distance Brillouin fiber sensing technologies based on time-division multiplexing, frequency division multiplexing, pulse coding, wide-bandwidth frequency modulation and image processing methods. The review article " Advances of key technologies on distributed fiber system for multi-parameter sensing" presents the theoretical basis of optical time domain reflectometry based on various scattering mechanisms, and introduced wide-frequency vibration measurement based on Rayleigh scattering, dynamic strain measurement based on Brillouin scattering and multi-parameter measurement based on multiple scattering mechanisms. " Recent progress of accurate measurement for distributed polarization crosstalk of fiber optic polarization component and device" reviewed the research progress of distributed polarization crosstalk of fiber optic polarization components and devices based on optical coherence domain polarimetry. The article "High-resolution fiber Bragg grating sensor and its applications of geophysical exploration, seismic observation and marine engineering "focuses on the core devices and key techniques required for high-precision FBG sensing system and their applications in geophysical exploration, seismic observations and ocean observations. "Recent advances in fiber optofluidic sensors" reviews the recent advances in fiber optofluidic lasers and passive fiber optofluidic sensors. The review article "Optical Fiber Acoustic Sensors" presents the theoretical basis and performance of several optical fiber acoustic sensing technologies. In short, these reviews and research papers inevitably grants the author an intensive understanding of the research status, trends and application prospects of the optical fiber sensing technology and equally provide useful help for researchers in related research fields.