Differences and Applications of LC / SC / ST / FC Fiber Connectors ？

1. Core Parameter Overview

2. Detailed Introduction & Application

LC Connector (Small Square)

• Structure: Compact square design with spring latch, available in duplex integrated jumpers.
• Features: Half the size of SC, highest port density, easy plug-and-play, low insertion loss.
• Application:
  1. Data centers, rack switches, SFP/SFP+/QSFP optical modules.
  2. 10G/25G/100G high-speed fiber links.
  3. High-density patch panels and server rooms.

Its products mainly include：

LC UPC to LC UPC Switchable Uniboot Duplex OS2 Single Mode LSZH 2.0mm Fiber Optic Patch Cable

LC APC Duplex OS2 Single Mode LSZH 2.0mm Fiber Optic Patch Cable

SC Connector (Large Square)

• Structure: Square push-in design, locks directly after insertion, no rotation or screwing needed.
• Features: Cost-effective, durable, simple operation, low failure rate.
• Application:
  1. Home broadband, optical modem, operator fiber access.
  2. PON fiber, FTTH access, general enterprise LAN.
  3. Ordinary fiber transceivers and weak current cabinet wiring.

Its products mainly include：

OM3 Multimode Duplex SC UPC to SC UPC OFNP Fiber Cable

Simplex OS2 Single Mode SC APC to SC APC PVC (OFNR) Fiber Optic Cable

ST Connector (Round Bayonet)

• Structure: Round shape, lock by rotating 90° after insertion.
• Features: Good tensile resistance, bulky and space-consuming, gradually phased out.
• Application:
  1. Legacy campus networks, old factories and building cabling.
  2. Security monitoring and industrial fiber points.
  3. Renovation of existing old equipment.

Its products mainly include：

Duplex OM2 Multimode LC UPC to ST UPC PVC (OFNR) Fiber Optic Cable

Duplex OS2 Single Mode LC APC to ST APC PVC (OFNR) Fiber Optic Cable

FC Connector (Round Threaded)

• Structure: Round with threaded nut, fixed by screwing tightly.
• Features: Excellent vibration resistance, stable connection, good dustproof and anti-loosening performance; slow wiring and large size.
• Application:
  1. Telecom room ODF patch panels and backbone trunk transmission.
  2. Base stations, microwave communication and outdoor high-vibration environments.
  3. Fiber optic test instruments and precision communication devices.

Its products mainly include：

SC LC FC ST Optical Fiber Patch Cable 50/125μm UPC to UPC Duplex OM2 Multimode LSZH (OFNR) 3.0mm

SC LC FC ST OS2 Switchable Optical Fiber Patch Cable Duplex Multimode LSZH (OFNR) 3.0mm Fiber Optic

3. Key Differences Summary

1. Ferrule: LC is 1.25mm; SC/ST/FC are all 2.5mm.
2. Connection Method:
   • LC / SC: Direct plug and play, fastest operation.
   • ST: Twist to lock.
   • FC: Screw tight, most stable but slowest.
3. Density Ranking: LC > SC > ST > FC
4. Vibration Resistance Ranking: FC > ST > SC > LC

4. Selection Guide

• Data center high-speed, optical module, high density → Choose LC
• Home broadband, optical modem, general office networking → Choose SC
• Legacy equipment, old campus surveillance → Choose ST
• Room patch panel, base station, precision testing, trunk line → Choose FC

Supplement: All four connectors have UPC (Blue) / APC (Green) end types, do not mix connections.