Today, Wuxi Rihuan Sensing Technology Co., Ltd. will introduce optical fiber sensors to you: the technical core, application scenarios and the panoramic view of industrial development.

As an important branch derived from optical fiber technology, optical fiber sensors have become a key support for the intelligent upgrade of multiple fields due to their unique performance. The following is a detailed elaboration from the core dimensions point by point:

I. Basic Technology System

1. Core principle

Relying on the characteristics of optical fiber waveguides, total reflection transmission of light is achieved through the refractive index difference between the core and the cladding.

By means of the modulation and demodulation process of optical signals, the measured physical quantities are converted into detectable optical/electrical signals. The core performance is affected by the loss and dispersion of optical fibers.

2. Two major categories

Functional type (FF type) : The optical fiber itself is a sensitive component, featuring both perception and signal transmission functions. It has high detection sensitivity but strict requirements for optical components.

Non-functional type (NF type) : Optical fibers are only used as light transmission media, relying on external sensitive components to modulate optical signals. They have a simple structure, high reliability, and a wider range of applications.

3. Mainstream modulation methods

Light intensity modulation: By changing the light intensity through the micro-bending effect, external modulation or refractive index modulation, demodulation must ensure a high signal-to-noise ratio.

Polarization modulation: By using electro-optic, magneto-optic and other effects to change the polarization state of light, and then converting it into a change in light intensity through a polarizer to achieve detection.

Phase modulation: By using interferometry technology to convert phase changes into amplitude changes, it is suitable for high-precision measurements.

Frequency modulation: Based on the optical Doppler effect, it acquires the motion information of the object under test by detecting the frequency offset of the light.

Ii. Key Products: Fiber Bragg Grating Sensors

1. Structure and Principle

The core of the fiber is doped with single crystal germanium ions, and after being irradiated by ultraviolet light interference, a Bragg grating (FBG) with periodically changing refractive index is formed.

Precise measurement of physical quantities is achieved by detecting the grating period or effective refractive index changes caused by the measured parameters.

2. Main Types and Applications

Temperature sensor: Based on thermal expansion and contraction and thermal optical effects, it is encapsulated in a capillary steel pipe and is used for monitoring the temperature of the environment and equipment.

Strain sensor: By utilizing the elastometric effect, it deforms in coordination with the adhesive and the object being measured, and is applied in the monitoring of building structures and mechanical components.

Pressure sensor: It converts pressure into strain through encapsulation sensitization technology and is suitable for pressure detection in pipelines and equipment.

Acceleration sensor: It converts displacement into strain by means of elastic elements and is used for vibration monitoring and equipment condition diagnosis.

Iii. Diverse Application Scenarios

Industrial and engineering monitoring

Liquid level monitoring: By using the principle of total internal reflection, the liquid level position is determined through sudden changes in light intensity.

Angular velocity monitoring: Fiber optic gyroscopes based on the Sagnak effect have an accuracy far exceeding that of traditional gyroscopes and are used for navigation and attitude control.

Current monitoring: Relying on the Faraday magneto-optical effect, it realizes contactless monitoring of high-voltage power grids.

Engineering safety: Monitor parameters such as tilt, settlement and strain in metro, reservoir dam and hydropower projects to ensure structural safety.

2. Medical and health care field

Cancer early screening: The dual-wavelength fiber laser sensor has increased the sensitivity of tumor marker detection by 2-3 orders of magnitude and has been clinically verified.

Disease marker detection: The sensitivity of the sandwich structure optical fiber sensor has been increased by two orders of magnitude, enabling the detection of extremely low-content markers.

3. New Energy and Battery Monitoring

Temperature monitoring: The FBG sensor is embedded inside the battery, with a measurement accuracy of 10pm/℃, preventing thermal runaway.

Strain/stress monitoring: It reflects the charging and discharging status of the battery through wavelength shift and warns of overcharging risk.

Electrolyte and spectral monitoring: Detect changes in the refractive index of the electrolyte, track electrode phase change and the decomposition process of the electrolyte.

4. Robots and Bionic Technology

Multimodal tactile sensing soft robotic finger, capable of recognizing a contact force of 0.01N, accurately distinguishing material properties and sliding directions.

It is applicable to scenarios such as human-computer interaction and medical devices, and can skillfully grasp fragile or transparent underwater objects.

Iv. Domestic Industrial and Scientific Research Progress

1. Breakthroughs in scientific research and technology

Northeastern University: Overcoming challenges such as trace substance detection and sensitivity control, the temperature resolution of deep-sea exploration sensors reaches 0.001℃.

Jinan University: Developed the world's first navigation-grade precision hollow core fiber optic gyroscope, with zero bias instability of 0.0017°/h.

Academician Jiang Desheng's team: Breaking foreign blockades, developing fiber Bragg grating temperature-sensing fire alarm systems, equipped 20,000 kilometers of tunnels and 90% of oil depots.

2. Enterprise and industrial landing

Heqi Optoelectronics: A leading player in the power electronics field, it has received 150 million yuan in financing and its products have been selected as typical cases of safety and emergency equipment by the Ministry of Industry and Information Technology.

Bai 'an Technology: Built the first 6-inch MEMS optical fiber sensor chip production line in China, with an annual production capacity of 10,000 to 15,000 pieces.

Jikang Technology: Serving the water conservancy and energy sectors, participating in major hydropower projects, with net profit achieving positive growth for seven consecutive years.

Guangge Technology: The market leader in distributed optical fiber sensing, and has served customers in multiple fields since its listing on the STAR Market.

V. Future Development Trends

Chipization and integration: Promote the miniaturization and low cost of demodulation instruments, break the reliance on discrete chips, and facilitate large-scale application.

Multimodal and intelligent: By integrating AI and big data to achieve multi-parameter collaborative monitoring, develop an intelligent analysis system, and support fault early warning.

Deepening of application scenarios: Expand applications in special fields such as deep-sea exploration and aerospace, and promote the clinical implementation of minimally invasive medical detection and real-time monitoring.