Fiber Optic Connector Types

The connector is the part that physically mates the fiber to the transceiver or bulkhead. It changes what looks compatible and what actually is.

There are roughly nine connector families in common use.

LC — Lucent Connector

Small form factor. Pull-latch tab, roughly half the size of an SC. The default for modern data centers because you can fit twice as many in a switch port panel. Ferrule diameter 1.25 mm.

Look for LC when: everything’s SFP+, SFP28, QSFP, QSFP28 — LC-LC is the default patch cord in modern data centers.

SC — Subscriber Connector

Square, snap-in coupling. Larger than LC. Common on older enterprise gear, GPON residential drops, and telecom infrastructure. Ferrule 2.5 mm.

Look for SC when: you’re patching to legacy panels or PON-style networks.

ST — Straight Tip

Round bayonet-lock. Twist to seat. Very common in older 1G/10G enterprise LANs and building risers built before the LC era took over.

Look for ST when: you’re bridging legacy panels — often paired with an LC on the other end for retrofits.

FC — Ferrule Connector

Round, threaded screw-on. Vibration-resistant. Popular in metrology, test equipment, and telecom trunk connections where mechanical stability matters more than swap speed.

MPO / MTP — Multi-fiber Push-On

Rectangular ferrule carrying 8, 12, 16, 24, or more fibers at once. The backbone of parallel-optics — 40G-SR4 (8 fibers), 100G-SR4 (8), 100G-SR10 (24). MTP is US Conec’s improved variant of the MPO standard — spec-compatible.

Look for MPO/MTP when: you’re deploying 40G/100G parallel optics, structured cabling with cassette breakouts, or dense trunk cables.

MU — Miniature Unit

Even smaller than LC. Common in Japanese carrier gear. 1.25 mm ferrule with a push-pull latch.

E2000

Push-pull latch with a spring-loaded shutter that closes over the ferrule when unmated. Popular in Europe and in high-power laser applications where dust ingress is a concern.

MTRJ — Mechanical Transfer Registered Jack

Small-form dual-fiber connector shaped like an RJ-45. Mostly found in older enterprise cabling.

SMA — Sub-Miniature Assembly

Screw-on connector originally from RF/microwave. Used in industrial fiber-optic sensors and some medical laser delivery systems.

Choosing the right connector

Follow the port. If the switch has SFP28 cages, you need LC. If the trunk cassette accepts MPO/MTP, you need MPO/MTP. If a legacy patch panel is ST, use LC-ST hybrid cords to bridge.