Fiber optic sensing systems have become indispensable in monitoring critical infrastructures such as power substations, oil and gas pipelines, tunnels, railways, and perimeter security. As these systems continue expanding in scale and complexity, ensuring the stability, reliability, and efficiency of optical paths becomes increasingly important. Optical switches play a central role in this process, safeguarding signal integrity, enabling multi-channel management, supporting system scalability, and reducing deployment and maintenance costs.

1. Optical Path Switching and Protection

In fiber optic sensing systems, the stability and reliability of the optical path are directly related to the monitoring accuracy and data integrity of the system. However, due to Rayleigh scattering of the fiber itself, reflections from fiber connectors or fusion splices, and the influence of external environmental factors, reflected optical waves are inevitably generated in the system. These reflected waves interfere with the normal operation of the system and reduce monitoring accuracy. Optical switches can rapidly switch optical paths to ensure that when a fiber link failure occurs, the optical signal can be quickly switched to a backup path, thereby achieving network protection switching.

Taking distributed fiber temperature sensing systems as an example, when a section of fiber in the system experiences signal attenuation or interruption due to environmental changes or physical damage, the optical switch can immediately detect the abnormality and switch to a backup fiber path, ensuring the continuity and reliability of monitoring data. This protection mechanism is particularly important in the monitoring of critical infrastructure such as substations, oil pipelines, and tunnels, as it can effectively prevent monitoring blind spots and safety risks caused by fiber failures.

The protection function of optical switches is not only reflected in the switching of physical paths but also in the isolation at the signal level. Mechanical optical switches provide an isolation mechanism composed of a polarizer, rotator, and analyzer, which can generate more than 35 dB of loss against reflected light and effectively suppress the impact of reflected light on the system. This high-isolation characteristic makes optical switches indispensable protective components in fiber optic sensing systems.

2. Multi-Channel Signal Management and Distribution

Fiber optic sensing systems usually need to monitor multiple physical quantities or cover large-scale areas, thus requiring multi-channel signal processing capabilities. Optical switches can distribute different wavelengths or different intensities of optical signals to different sensing channels at the same time, achieving multi-path signal interconnection and distribution. This capability not only improves monitoring efficiency but also reduces system complexity and cost.

For example, in distributed fiber temperature sensing systems, embedding a 1×4 optical switch can expand the original single sensing fiber into four paths, increasing the total sensing fiber length to four times the original—achieving a monitoring distance of 120 km (the original system was only 30 km). In practical applications, the driver interface of the optical switch is controlled by a microcontroller. The computer sends switching commands through a serial port, and the driver interface converts these commands into corresponding electrical level signals to control the optical switch to switch to different channels. After completing the switching, the system can perform temperature measurements on the corresponding channel, achieving synchronized multi-channel monitoring.

The application of optical switches in signal distribution is not limited to temperature sensing systems. In vibration sensing, acoustic field monitoring, and other systems, optical switches can also achieve flexible switching and management of multi-path signals. Through the time-division multiplexing characteristics of optical switches, the optical signal from the same light source can be distributed to different sensing channels for multi-point and multi-parameter synchronous monitoring, greatly enhancing monitoring efficiency and coverage.

3. System Flexibility and Scalability

With the continuous development of fiber optic sensing technology, systems need greater flexibility and scalability to adapt to changes in different scenarios and requirements. Optical switches can dynamically adjust the transmission path of optical signals according to system needs, enabling flexible configuration and expansion of sensing systems. This capability allows fiber sensing systems to better adapt to complex and variable application environments.

In large-scale distributed fiber sensing networks, optical switches can be cascaded and combined to form complex optical path topologies, enabling flexible connections and switching between different areas and channels. For example, in oil and gas pipeline vibration monitoring systems, optical switches can cooperate with time-slicing technology to rapidly collect and analyze vibration signals from multiple pipeline sections, effectively improving monitoring efficiency and positioning accuracy.

The scalability of optical switches is also reflected in their ability to support configurations ranging from simple 1×2 and 2×2 to complex 1×N and M×N matrix structures. By reasonably designing the cascading and combination methods of optical switches, it is possible to build sensing systems of different scales, meeting various needs from small laboratory experiments to large-scale industrial deployments. This flexibility allows fiber sensing systems to perform optimally in different application scenarios and provides users with more economical and efficient solutions.

4. Reducing System Complexity and Cost

The deployment and maintenance costs of fiber optic sensing systems are important factors affecting their widespread application. Optical switches can effectively reduce the number and complexity of fiber connectors in the system, lower system costs, and improve reliability. In traditional distributed fiber sensing systems, multi-path signal management usually requires a large number of fiber connectors, which not only increases system cost but may also cause signal attenuation and instability due to poor contact or contamination.

By introducing optical switches, the management of multiple signals can be centralized inside the optical switch, reducing the number of external fiber connectors. For example, in distributed fiber temperature sensing systems, the switching function of optical switches allows multiple sensing channels to be integrated between a single light source and detector, significantly reducing the number of physical connection points and lowering deployment and maintenance costs. Meanwhile, the high isolation and low return loss characteristics of optical switches can effectively reduce signal interference caused by reflected light, improving system stability.

In practical applications, the introduction of optical switches not only reduces system cost but also enhances maintainability. When a fault occurs in a certain channel, the system only needs to control the optical switch to switch to a backup channel without replacing the entire fiber link, greatly simplifying the maintenance process and reducing maintenance expenses.

GLSUN is a high-tech enterprise specializing in the R&D and manufacturing of passive optical communication components, established in 2001. The company’s core competitiveness lies in the optical design, manufacturing, testing, and packaging technologies of passive optical devices. Its main products include mechanical optical switches, MEMS optical switches, wavelength division multiplexers, optical isolators, optical circulators, and others. These products are widely used in fiber optic sensing, communication networks, and optical testing fields.