LC Connector
Direct Answer
The LC connector (Lucent Connector, TIA-604-10 / FOCIS-10) is a small form-factor (SFF) optical connector utilizing a 1.25 mm ceramic ferrule and an RJ45-style push-pull latching clip, widely used in enterprise datacenters and optical transceivers (SFP/SFP+/SFP28).
Source: TIA-604-10-B (FOCIS-10) / IEC 61754-20
Specs
| Standard / FOCIS | TIA-604-10-B (FOCIS-10) / IEC 61754-20 |
| Ferrule Diameter | 1.25 mm |
| Ferrule Material | Zirconia ceramic |
| Latching Mechanism | Push-pull with retention clip (RJ45-style) |
| Fiber Modes Supported | Single-Mode (OS1/OS2) and Multi-Mode (OM1–OM5) |
| Typical Insertion Loss | 0.10–0.25 dB |
| Polish Types Available | UPC (Ultra Physical Contact, Blue) and APC (Angled, Green) |
| Duplex Clip Pitch | 6.25 mm |
Small Form Factor (SFF) Dominance
Developed by Lucent Technologies, the LC connector cut the standard 2.5mm ferrule size in half to 1.25mm. By matching the footprint of standard RJ45 copper jacks and transceiver cages, duplex LC connectors enabled double the density of SC connectors on patch panels and line cards.
UPC vs APC Polishing
LC connectors are available in two optical end-face polishes:
- UPC (Blue housing): Flat/dome contact with return loss > -50 dB, standard for enterprise datacenters and multi-mode fiber.
- APC (Green housing): 8-degree angled contact reflecting stray back-reflections into the fiber cladding, achieving return loss > -65 dB (essential for FTTH, RF video, and DWDM single-mode systems).