Basic Definition
LC: Lucent Connector, a small form-factor fiber connector with 1.25mm ceramic ferrule, widely used for SFP/SFP+ optical modules in high-density ports.
UPC / APC refer to fiber end-face polishing types:
- LC UPCFull name: Ultra Physical ContactEnd face: 0° flat with slight convex dome polishing

- LC APCFull name: Angled Physical ContactEnd face: 8° angled bevel polishing

Core Differences
| Item | LC UPC | LC APC |
|---|---|---|
| End-face Angle | 0° vertical convex | 8° angled slope |
| Housing Color | Blue | Green |
| Return Loss (RL) | ≥ -50 dB | ≥ -60 ~ -65 dB |
| Insertion Loss (IL) | 0.2 ~ 0.3 dB | Slightly higher ~ 0.3 dB |
| Reflection Feature | Reflected light returns along the original path | Reflected light deflects into cladding and dissipates |
| Application Scenarios | Data center, enterprise network, multi-mode fiber (OM3/OM4/OM5), general single-mode short/medium transmission | CATV, PON/FTTH, WDM/DWDM, long-haul transmission, reflection-sensitive optical systems |
| Compatibility | Cannot mate with APC directly | Must connect APC to APC only |
Selection Rules
Choose LC UPC (Blue)
- Data center, switch-to-server connection, ordinary fiber transceivers
- OM3/OM4/OM5 multimode fiber links
- Common single-mode links without WDM or analog video signals
Choose LC APC (Green)
- CATV & IPTV broadcast systems
- PON / FTTH fiber access networks
- WDM/DWDM long-distance transmission
- Systems with strict requirements for low reflection and laser service life
Important Note
Do not mix UPC and APC connectors; mismating blue and green connectors will cause severe loss degradation and even damage optical modules. The entire link (patch cord, adapter, device port) must use the same polishing type.
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LC UPC Simplex Field Assembly Mechanical Connector, OM2/OM3/OM4/OM5 Multimode Quick Field Termination Connector 



