Optical Fiber Connector end-face Contact Method: PC, UPC, APC

1. There are three types of fiber connector end-face contact: PC, UPC, and APC.

2. PC - The end face of the pin body is a physical end face;

UPC - The end face of the pin body is super physical end face;

APC - The end face of the pin body is an angle physical end face;

3. In addition to the physical difference, the difference between the three is return loss, that is, the reflection loss is different. The difference is that the return loss is: PC ≥40dB, UPC ≥50dB, APC ≥60dB.

4. Three common optical fiber connectors:

FC / PC:

FC, round head pigtail connector. PC, the ceramic cross-section is flat;

SC / PC:

SC, square head pigtail connector. PC, the ceramic cross-section is flat;

FC / APC: 

FC, round head pigtail connector. APC, with the center of the section as the center of the circle, inclined outward by 80 degrees.

5. The difference between LC, SC, FC

LC, SC, FC, etc. refer to the overall size of the pigtail.

LC fiber optic connector

The LC connector is researched and developed by the famous Bell Research Institute and is made of a modular jack (RJ) door lock mechanism that is easy to operate. The size of the pins and sleeves used is half the size of ordinary SC, FC, etc., which is 1.25mm. This can increase the density of optical fiber connectors in the optical fiber distribution frame. At present, in terms of single-mode SFF, LC-type connectors have actually occupied a dominant position, and their applications in multi-mode have also grown rapidly.

1) LC-APC

Features:

Small size, high dimensional accuracy

1.25mm ceramic ferrule

Low insertion loss

High return loss

Single-core/dual-core structure is optional

Comply with IEC874 standard

application:

Telecommunications and data communications

LAN

Wide area forget

Device terminal

2) LC-PC

Insertion loss (dB) ≤ 0.20

Maximum insertion loss (dB) ≤0.30

Return loss (dB) ≥ 45

Repeatability (dB) 0.1

Mating times 1000 times

Fiber Type Corning SMF-28TM 9/125um

Working temperature (℃) -40 ~ +75

Working standard IEC60874

3) LC-UPC

Insertion loss (dB) ≤ 0.20

Maximum insertion loss (dB) ≤0.30

Return loss (dB) ≥ 50

Repeatability (dB) 0.1

Mating times 1000 times

Fiber Type Corning SMF-28TM 9/125um

Working temperature (℃) -40 ~ +75

Working standard IEC60874

According to different classification methods, optical fiber connectors can be divided into different types. According to different transmission media, it can be divided into single-mode fiber optic connectors and multi-mode fiber optic connectors. According to the different structures, it can be divided into various types of connectors such as FS, SC, ST, D4, DIN, Biconic, MU, LC, and MT. According to the pin end face of the connector, it can be divided into FC, PC (UPC), and APC. According to the number of fiber cores, it is divided into single-core and multi-core.

6. The difference between fiber optic adapter PC, APC, and UPC

PC, UPC, and APC all refer to the pin end face of the optical fiber connector.

The common fiber optic connectors in the laboratory mainly include FC / PC and FC / APC. The FC here refers to the foot ferrule contactor, which is a metal sleeve made of steel (the difference between optical fiber connectors and cable connectors is the metal texture. Cable connectors are mostly made of copper, mainly for good conductivity. And optical fiber connectors is no electrical conductivity. Besides, copper is soft, expensive, and rusty). For connectors that are all metal, these two abbreviations are often ignored. For example, FC / PC can be conventionally called PC, and APC refers to FC / APC.

PC refers to physical contact. The same is close contact. According to the difference in return loss, the connectors are divided into PC, SPC, UPC, and APC. SPC refers to super physical contact, and UPC refers to ultra physical contact. PC, SPC, and UPC industry standards specify the return loss of -35dB, -45dB, and -50dB respectively (Return loss refers to the proportion of light reflected by the end face of the connector. The smaller the return loss, the better. In other words, do not consider negative numbers, the larger the value, the better). Different connectors cannot be mixed in principle, but the fiber end faces of PC, SPC, and UPC are all flat, the difference lies in the quality of the model. Therefore, the mixed connection of PC, SPC, and UPC will not cause permanent physical damage to the connector.

APC is completely different. Its end face is ground to an 80-degree angle to reduce reflection. The industry standard return loss is -60dB. The APC connector can only be connected with APC. Since the structure of APC is completely different from that of PC, if a flange is used to connect these two connectors, the fiber end face of the connector will be damaged. The way to connect APC to PC: It is realized by fiber jumper for PC to APC conversion. Another thing to note is that the APC connector is usually green (and the yellow fiber is only a single-mode fiber), and the human eye can see the tilt of the fiber end face.

Therefore, in order to avoid the confusion of the use of connectors during the experiment (to avoid damaging the input ports of the spectrometer), when purchasing lasers, jumpers, etc., manufacturers should be required to provide APC connectors. FC / PC, FC /UPC, FC / APC can be connected in a mixed manner, and the signal attenuation will not be very large. According to the national standard, the insertion loss should be less than 0.5 dB. The application mainly depends on the type of adapter. Generally, FC is used for ODF frame, SC is used for optical port of equipment, and ST is used for LAN and broadcasting.