Why are these connectors blue? Can they be plugged into the green (APC) connectors?
The blue color on a fiber optic patch cord connector typically signifies a PC (Physical Contact) or UPC (Ultra Physical Contact) polish.
Why are these connectors blue?
In the fiber optics industry, color coding is used to quickly identify the polish type of the connector ferrule:
- Blue: Represents PC or UPC (Physical Contact / Ultra Physical Contact). These have a flat or slightly domed end-face polish.
- Green: Represents APC (Angled Physical Contact). The end-face is polished at an 8-degree angle to minimize back-reflection.
Can they be plugged into green (APC) connectors?
No, you should never plug a blue (PC/UPC) connector into a green (APC) connector.
Doing so will cause two major issues:
- Technical Failure: Because the APC connector is angled and the UPC connector is flat, the fiber cores will not align properly. This results in extremely high insertion loss and very low return loss, which will likely cause your sensing system or network to fail.
- Physical Damage: Forcing these two different surface types together can permanently scratch or dent the delicate polished surfaces of both connectors, rendering them useless.
DCYS (OFSCN®) Solutions
At Beijing Dacheng Yongsheng Technology Co., Ltd. (OFSCN), we provide various fiber optic components and FBG sensors with customizable connector types to match your specific system requirements.
For high-performance sensing applications, we often recommend FC/APC connectors (Green) because they offer superior return loss, which is critical for the stability of Fiber Bragg Grating (FBG) signals.
Related Products:
- OFSCN® Standard Fiber Patch Cord: Available with FC, ST, LC, SC connectors in both PC/UPC and APC polishes.
- OFSCN® 300℃ Fiber Optic Connector: Specialized connectors for high-temperature environments, supporting various polish types.
Standard Product Image:
If you are using an FBG interrogator, please check the port color on the device. If the port is green, ensure you use green (APC) patch cords. If you have any specific technical questions regarding connector compatibility in your project, feel free to ask.