PC vs UPC vs APC Connector: How to choose?

    When choosing fiber optic cables or fiber connectors, the most common questions one might focus on based on their fiber installation. But an often overlooked question is: “Which fiber connector polish should I use, and What’s the difference between these fiber connector polishes? ”Continue reading this article and I am sure your question will be answered. .

     First, we will mention the three most common polish types. There are three main types of fiber connector polishes used in today’s fiber optic applications.

• PC (Physical Contact

• UPC (Ultra Physical Contact) 

• APC (Angled Physical Contact)

 Introduction to Different Connector Types

    In brief, PC, UPC, and APC define the type of polish used on the fiber optic connector end face or ferrule. 

    The ferrule secures the bare fiber tip, letting you link one fiber to another, or plug the fiber into light transmitters and receivers.Once you fit a connector to the fiber end, some light bounces back to the light source and messes up the signal.To make fiber transmission work better, engineers polished the fiber’s contact surface, creating today’s ferrule polishing technologies.

    We will get back to the 3 fiber connector polish types in more detail in the following sections.

PC Fiber Connector

    A PC fiber connector features a Physical Contact polishing profile, the most widely used finish for OM1 and OM2 multi-mode fiber jumpers.The PC design was developed to solve a key flaw of early flat-end connectors: tiny surface defects would leave an air gap between two mated fiber ends.The PC connector was invented to fix this issue: its gently curved fiber end face greatly reduces or removes those air gaps.Nevertheless, this polishing type is now obsolete, having been superseded by its upgraded iteration — the UPC polishing standard.

UPC Fiber Connector

    UPC, short for Ultra Physical Contact, is the upgraded iteration of the PC fiber connector and currently the most widely adopted polishing standard for fiber optic deployments.It keeps PC’s curved end face and uses longer polishing to form a smoother surface, cutting back reflection greatly for steady signals in data, telephone and TV transmission, covering most fiber application demands.

    UPC’ s bad performance seldom comes from its design. Poor fiber cutting and polishing are the main causes, and fiber cleave quality directly affects its return loss even for factory pre-polished products. Besides, frequent plugging and unplugging will scratch the end face and degrade its overall performance.

APC Fiber Connector

    Out of the pursuit of lower back reflection, APC fiber connectors were developed. APC refers to Angled Physical Connect, the ferrule endface radius of which is polished at an 8°angel, minimizing the back reflection as a result. Since adding the angled endface, the reflected light will leak out into the cladding instead of staying in the fiber core. It should be noted that APC connectors should only be mated with other angled-polished connectors rather than non-angled polished connectors, or it will cause very high insertion loss. The optical return loss of APC connectors is -60dB or higher, better than the other connector types.

PC vs. UPC vs. APC: What Are Their Differences?

     Once we clarify the three mainstream fiber connector polishing types.Below is a detailed comparison covering physical appearance, optical transmission performance and typical application scenarios.

Appearance

A. Fiber Endface Polishing: The core visual distinction lies in fiber endface geometry:

• PC & UPC adopt 0° flat polishing; UPC features a mild spherical curved endface for tighter core contact, while PC has a fully flat surface.
• APC uses an 8° angled endface to deflect reflected light.

 B. Connector Housing Color Coding (Universal Industry Standard)Shell color serves as a quick visual identifier for polishing grades:

• Single-mode LC APC: Green housing
• Single-mode LC UPC: Blue housing
• Supplement: Legacy single-mode PC connectors are gray;multi-mode LC UPC typically uses beige/black shells.

Performance

A. Insertion Loss

    Early APC connectors suffered high insertion loss due to air gaps from fiber core offset at the tip. Thanks to upgraded connector design and manufacturing techniques, modern APC products deliver much better performance. The insertion loss gap between APC and UPC has been greatly narrowed.

 B. Return Loss

    APC’ s 8° angled endface effectively diverts reflected light, giving it the weakest back reflection among PC, UPC and APC types.Industry standard return loss benchmarks:

• PC: ~ -40 dB
• UPC: ~ -50 dB
• APC: ≥ -60 dB

    A higher return loss value means less reflected light and superior signal stability. This makes APC the highest-performance polishing type for anti-reflection scenarios.

Application

A. Fields that demand strict control of return loss — APC connectors are the first choice.

Common specific scenarios:

• RF video signal transmission (long wavelength signals)
• FTTX fiber access projects
• Passive Optical Networks (PON)
• Single-mode WDM systems with long-wavelength signals

 B. Fields with low requirements for return loss — UPC or PC connectors are adopted.

Specific usage breakdown:

• PC connectors: Widely applied in traditional telecom operator equipment
• UPC connectors: Mainly used for digital TV, telephone communication and general data transmission systems

Conclusion

    There is no single "best" polish type among PC, UPC and APC fiber connectors.Selection depends on project cost, on-site operability and actual signal demands:

•     Pick APC for high-precision optical systems sensitive to reflected light.
•     Choose PC or UPC for regular digital transmission systems with low reflection requirements.