Tag Archives: fiber optic

Fiber Optic Connectors – Standards to Ensure Physical Contact

As we know, physical contact is most important to ensure low IL and high RL for fiber connection. The evolution of endface polishing types experiences physical contact (PC), ultra physical contact (UPC) and angled physical contact (APC), as shown in Fig.1. All the endfaces are spherically polished. The UPC connector has a smaller radius of curvature than the PC connector. For the APC connector, the sphere surface is usually tilted by an angle of 8°. The RL guaranteed by PC, UPC and APC is 40dB, 55dB and 65dB, respectively.

Fig.1 Polish types for the endfaces of fiber optic connectors
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Fiber Optic Connectors—Basics for Optical Fiber Connection

Fiber optic connectors are the most basic optical passive components for optical fiber communication systems. The basic specification requirements for them are low insertion loss (IL) and high return loss (RL), i.e. low back reflection (BR). However, as the most widely employed components, low cost and easy connection are equal important as the specifications.

Alignment of Optical Fibers
The core size of the single mode fiber (SMF) is about 8~10μm. The two connected fibers must be precisely aligned to ensure low loss. Fig.1 shows how much the lateral offset between two optical fibers influence the IL. The curve is exponential. A small lateral offset such as 2.4μm will introduce IL of 1dB. Thus the lateral offset between the two fibers must be kept <0.5μm for SMF fiber optic connectors.

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