The function of fiber optic circulator

Fiber optic circulators are the core components in 5G base stations, providing signal isolation and ensuring bidirectional optical signal transmission. With the development of 5G Massive MIMO, its demand has significantly increased. Ringers are classified by port and polarization, and are commonly used in passive optical networks WDM、 Applications such as dispersion compensation.

1、 What is a fiber optic circulator?

Fiber optic circulator is a non reciprocal optical passive device, whose core function is to control the sequential transmission of optical signals along specific directions. Fiber optic circulator is a unidirectional device that directs optical signals from one port to another, with only unidirectional transmission at a time. Although the optical signal can be redirected as needed, it must pass through each port sequentially (i.e., before reaching port 3, it must first pass through ports 1 and 2). In addition, fiber optic circulators can be used to achieve bidirectional transmission on a single fiber optic cable. Due to its low insertion loss and high isolation of input and reflected optical power, fiber optic circulators are widely used in advanced communication systems and fiber optic sensor applications.

2、 The three core functions of a circular device

Realize bidirectional transmission of single fiber, significantly saving fiber resources

Traditional technology requires two optical fibers to be responsible for sending and receiving separately. The circulator allows for bidirectional communication within a single optical fiber, reducing fiber demand and cost by 50% directly. This is a key technology in the 5G fronthaul network (eCPRI).

Separate optical signals to protect system safety

It can strictly isolate strong emitted light from weak received light, prevent the emitted light from reflecting back to sensitive lasers or detectors, and avoid equipment burning or interference.

Recovering light energy to improve system efficiency

In fiber amplifiers, circulators can redirect and utilize underutilized residual pump light or scattered light, significantly improving amplifier efficiency and reducing overall power consumption.

3、 Product classification

Fiber optic circulators are classified based on the number of ports and polarization processing capabilities:

Classified by number of ports:

The most common type is the three port circulator, which has a compact structure and high cost-effectiveness, and is widely used in general bidirectional communication and optical amplification systems. Four port and multi port circulators provide more complex optical routing functions, with more diverse path designs, mainly used in scientific research systems and specific scenarios that require complex optical path management.

Classified by polarization characteristics:

Polarization independent (PI) circulators are insensitive to the polarization state of input light and are suitable for most general scenarios. They have become the preferred choice for mainstream applications such as telecommunications networks and data centers. Another type is polarization maintaining (PM) circulator, which can maintain the polarization state of optical signals unchanged. It is mainly used in high-end fields that are sensitive to polarization, such as coherent communication, quantum communication, and high-precision fiber optic sensing systems.

4、Applications

5G and Telecommunications Networks

5G base station (AAU): Achieving single fiber bidirectional transmission is the key to cost reduction and efficiency improvement in Massive MIMO architecture. Passive Optical Network (PON): Separate upstream and downstream optical signals between OLT and ONU to ensure stable operation of your gigabit broadband at home.

Data Center and Cloud Computing

High speed optical module: used inside 100G/400G coherent optical modules to achieve isolation of transmitting and receiving signals.

Resource scheduling: Combined with optical switches, it can achieve dynamic and flexible scheduling of optical paths, improving data center efficiency.

Cutting edge Science and Industry

Fiber optic sensing: used for distributed acoustic sensing (DAS) and temperature sensing (DTS) to accurately monitor pipeline and perimeter safety.

Quantum Communication: Building a unidirectional optical path to ensure that fragile quantum signals are not disturbed during transmission.

5、 Future prospects

With the advancement of technologies such as 5G Advanced, 6G, Eastern Digital and Western Computing, and all-optical networks, the demand for network capacity, speed, and reliability is endless. Fiber optic circulators are also evolving towards lower loss, higher isolation, smaller size, and greater integration (such as when combined with silicon optical technology), continuing to play an indispensable "core hub" in the wave of optical communication.

Choosing ZG Tech, we are committed to providing a full range of high-performance and high reliability fiber circulator solutions to safeguard your 5G, data center, and sensor network construction.

References: //en.wikipedia.org/wiki/Optical_circulator