In today’s world of rapid information transmission, optical fiber communication has become the cornerstone of modern communication networks with its advantages of high speed and long-distance transmission. As key components in optical fiber communication systems, optical fiber end faces and connectors play a vital role.

I  Optical fiber end faces: PC, UPC, APC

1. PC (Physical Contact)

– Definition: The PC end face adopts physical contact. The end face is precisely ground and slightly spherical. The optical fiber core is located at the highest point of the bend, reducing the air gap and making the two optical fiber end faces physically contact.

– Features: simple manufacturing process, low cost, good stability, suitable for general data transmission, video transmission and voice transmission.

– Application scenarios: widely used in network environments such as data centers, local area networks, and metropolitan area networks, and commonly used in optical fiber connectors such as SC, FC, and ST.

– Standard: The return loss is -40dB.

2. UPC (Ultra Physical Contact)
– Definition: The UPC end face is optimized on the basis of PC, with better end face polishing performance and surface finish, and is dome-shaped.
– Features: Higher return loss (close to -50dB or higher), reducing the impact of reflected light and improving signal transmission quality.
– Application scenarios: Suitable for scenarios with high requirements for return loss, such as telecommunications networks, cable TV networks, and data centers.
– Standard: Return loss is -50dB.

3. APC (Angled Physical Contact)
– Definition: The APC end face is an 8° bevel, and the reflected light is reflected into the cladding at a certain angle to reduce return loss.
– Features: The highest return loss (-60dB or higher), reducing reflected light interference and improving signal transmission stability.
– Application scenarios: Suitable for scenarios with extremely high requirements for reflection loss, such as single-mode optical fiber communication systems, DWDM systems, and optical fiber sensors.
– Standard: Return loss is -60dB.

II  Mainstream fiber optic connectors and application scenarios

1. MPO (Multi-fiber Push-On)

– Definition: High-density, multi-fiber connector, supporting parallel connection of 8, 12, 24 and other multi-core optical fibers.

– Features: High density, scalability, fast speed, high efficiency.

– Application scenarios: Data centers, telecommunications, broadcasting, high-performance computing.

2. LC connector

– Definition: Miniaturized connector, the pin and sleeve size is 1.25mm.

– Features: Miniaturization, easy operation, stable performance.

– Application scenarios: Routers, switches and other equipment.

3. ST connector

– Definition: The shell is round and the fastening method is screw buckle.

– Features: Simple structure and good stability.

– Application scenarios: Fiber distribution frames, optoelectronic converters and other equipment.

4. FC connector

– Definition: The external reinforcement method uses a metal sleeve and the fastening method is a screw buckle.

– Features: High reliability and wide application.
– Application scenarios: fiber distribution frames, optical terminals and other equipment.

5. SC connector
– Definition: standard square connector, rectangular shell.
– Features: low price, small insertion loss fluctuation, high installation density.
– Application scenarios: transmission equipment side optical interface, routers, switches and other equipment.

6. MU connector
– Definition: the world’s smallest single-core fiber connector.
– Features: high-density installation, multiple series.
– Application scenarios: optical cable connection, bottom board connection, connection of LD/PD module and plug.

7. E2000 connector
– Definition: push-pull locking setting, the shell is made of engineering plastic.
– Features: easy to install densely, with dust cover.
– Application scenarios: single-mode fiber connection, high-density installation occasions.

III. Summary

Fiber optic connectors are devices for detachable connection between optical fibers, and they precisely dock the fiber end faces to ensure that the light energy is coupled to the receiving fiber to the maximum extent. The fiber end face type (such as PC, UPC, APC) and connector type (such as MPO, LC, ST, etc.) jointly determine the performance and reliability of the fiber optic communication system. Choosing the right end face and connector is crucial to building an efficient and stable fiber optic communication network.