What Is an MTP/MPO Cable? The Complete Beginner's Guide
An MPO cable is a fiber optic cable assembly terminated with MPO (multi-fiber push-on) connectors, which hold 8, 12, 16, 24 or more fibers in a single rectangular ferrule and connect them all in one push-pull action. MTP® is US Conec's brand of MPO connector: it complies with the MPO standards and mates with other compliant MPO connectors, but adds design refinements of its own. MTP/MPO cables are the standard way to build high-density structured cabling and parallel-optic links in data centers, from 40G SR4 to 800G DR8.
This guide explains what is inside an MPO connector, the fiber counts and formats you will see on a datasheet, how gender, polish and polarity work, and what to specify when you order MTP/MPO trunk cables or patch cords.
What Does MPO Mean?
MPO stands for "multi-fiber push-on". The connector was developed by NTT in Japan, building on the MT (mechanical transfer) ferrule that NTT introduced in 1986 for joining fiber ribbons. The MT ferrule places a row of fibers between two precision guide holes; two guide pins align one ferrule to another, so every fiber in the row lines up at the same time.
The MPO connector interface is standardized in:
- IEC 61754-7 – the international interface standard for the MPO connector family.
- TIA-604-5 (FOCIS 5) – the North American intermateability standard for MPO.
- TIA-604-18 (FOCIS 18) – the separate standard for MPO-16 connectors (16 fibers per row).
Because these documents define the mating dimensions, a compliant MPO connector from one manufacturer will mate with a compliant MPO connector from another.
MTP vs MPO: Brand vs Connector Type
MPO is the generic connector type. MTP® is a registered trademark of US Conec Ltd. for its MPO-style connector. In short: every MTP connector is an MPO connector, but not every MPO connector is an MTP connector.
US Conec lists several features that distinguish the MTP® connector from generic MPO designs:
- Removable housing – the ferrule can be re-polished, inspected interferometrically, or have its gender changed after assembly.
- Floating ferrule – helps two mated ferrules keep physical contact under side load.
- Elliptical stainless-steel guide pin tips – improve guidance and reduce wear of the guide holes.
- Metal pin clamp – retains the pins and centers the spring force.
Both connector types are used in the same networks and mate with each other. When a specification says "MTP", it is naming a specific brand of component, so decide whether genuine US Conec MTP® connectors or standard-compliant MPO connectors are required. Huawellux supplies assemblies with either. We cover the differences in more depth in MTP vs MPO: What's the Real Difference?
Anatomy of an MPO Connector
From the end face back, an MPO connector consists of:
- MT ferrule – a molded ferrule (typically a thermoplastic composite) with fibers on a 0.25 mm (250 µm) pitch. Multimode and single-mode versions exist, and precision grades are available for low-loss performance.
- Guide pins or guide holes – a male connector has two guide pins protruding from the ferrule; a female connector has two open guide holes.
- Pin clamp – holds the guide pins (male) or sits in their place (female) and seats the spring.
- Spring – pushes the ferrule forward so that the fiber end faces stay in physical contact when mated.
- Housing with key – the outer push-pull body. A raised key on one side sets the orientation; fiber position 1 is identified relative to the key.
- Boot – strain relief for round, oval or ribbon cable.
Two connectors are joined through an MPO adapter (bulkhead coupler). Inside, the guide pins of the male connector enter the holes of the female connector and align the two ferrules.
Fiber Counts and End-Face Layouts
MPO connectors are described by how many fibers they carry and how many rows they use:
| Format | Fibers | Rows | Typical use |
|---|---|---|---|
| MPO-8 | 8 | 1 (in a 12-position ferrule) | 4-lane parallel optics (SR4, DR4) |
| MPO-12 | 12 | 1 | The most common format; structured cabling and SR4/DR4 |
| MPO-16 | 16 | 1 | 8-lane optics such as 400G SR8 and 800G DR8 |
| MPO-24 | 24 | 2 × 12 | High-density trunks; one MDI option for 400G SR8 |
| MPO-32 | 32 | 2 × 16 | High-density 16-fiber systems |
Higher counts (48, 72 and beyond) exist for specialty high-density applications.
Two compatibility points matter in practice:
- MPO-16 is not compatible with MPO-12/24. FOCIS 18 uses the same ferrule footprint but a different guide-pin diameter and spacing, and an offset key, so it will not mate with a standard MPO-12 or MPO-24.
- MPO-12 and MPO-24 can physically mate, but will not work. The housings are the same size, so a mismatched pair can be plugged together even though half of the fibers have no partner. Label fiber count clearly on every assembly.
Male vs Female and Key Orientation
Unlike LC or SC connectors, every MPO connector has a gender:
- Male (pinned) – guide pins installed.
- Female (unpinned) – guide holes open.
A mated pair must always be one male and one female. Two male connectors cannot seat correctly and the pins can damage the end faces; two female connectors have no alignment pins, which gives high and unstable loss. As a common convention, transceiver ports are pinned, so the cable connector that plugs into a transceiver is usually female; check the equipment documentation.
MPO adapters come in two styles:
- Key-up to key-down (often called a Type A adapter).
- Key-up to key-up (Type B adapter).
The combination of adapter type and cable construction determines polarity, the mapping from fiber positions at one end to positions at the other.
MPO Polarity in Brief
TIA-568.3-D defines three polarity methods for MPO cabling:
- Type A (straight-through): position 1 to position 1, key up to key down.
- Type B (reversed): position 1 to position 12, key up to key up.
- Type C (pair-flipped): adjacent pairs swapped (1 to 2, 2 to 1, and so on).
Each component in a channel has its own polarity, and the full channel must deliver every transmitter to a receiver. For wiring diagrams and selection guidance, see our MPO polarity guide: Type A, B and C.
Polish and Fiber Type
End-face polish is specified per connector:
- Multimode MPO is normally a flat physical-contact (PC) polish, often listed as UPC.
- Single-mode MPO is normally an APC polish at 8°, which reduces back reflection. APC connectors are commonly green.
APC and flat-polished connectors must never be mated together: the angled and flat end faces do not make proper contact.
Fiber type follows the application:
- OM3 / OM4 multimode (jacket typically aqua) for short-reach SR links.
- OM5 wideband multimode (jacket typically lime green) where SWDM is planned.
- OS2 single-mode (jacket typically yellow) for DR/FR links and longer reach.
Types of MTP/MPO Cable Assemblies
The term "MPO cable" covers several assembly types:
- MPO trunk cable – MPO connectors on both ends, used for the permanent backbone between racks or rooms. Fiber counts range from 8 to 144 and above, with several MPO legs per end on high-count trunks.
- MPO patch cord – a short MPO-to-MPO jumper between a panel and a transceiver, or between two panels.
- MPO harness (fan-out / breakout) – MPO on one end and several LC duplex (or smaller MPO) connectors on the other, for example to break a 400G DR4 port into four 100G links.
- MPO-LC cassette – a module that converts MPO trunk ports to LC duplex front ports inside a patch panel.
Not sure which one you need? Read our comparison of MPO trunk cables vs patch cords, or browse MTP/MPO trunk cables and MTP/MPO patch cords.
Where MTP/MPO Cables Are Used
MPO connectors are the media interface for most parallel optics, where several fibers carry lanes at the same time:
| Application | Connector | Fibers used |
|---|---|---|
| 40GBASE-SR4 / 100GBASE-SR4 | MPO-12, multimode | 8 (4 Tx + 4 Rx, centre 4 unused) |
| 400GBASE-DR4 | MPO-12 APC, single-mode | 8 (Tx 1–4, Rx 9–12) |
| 400GBASE-SR8 | MPO-16 or MPO-24, multimode | 16 |
| 800GBASE-DR8 | MPO-16 APC, single-mode | 16 |
They are also used in structured cabling even when the equipment is duplex: a high-count MPO trunk is pulled once, then cassettes or harnesses break it out to LC at each rack. This lowers installation time and pathway fill compared with many individual duplex cables.
Performance and Quality Factors
Insertion loss. TIA-568.3-D allows up to 0.75 dB per mated connector pair in a channel loss budget, including MPO connections. Component makers offer low-loss grades with tighter limits; for example, US Conec specifies its low-loss MT ferrules at 0.35 dB maximum per mated fiber pair. With 400G and 800G optics, low-loss connectors leave more headroom in the channel budget. Huawellux's specification for MPO and MTP® assemblies (identical for both) is insertion loss ≤0.35 dB for single-mode and multimode, with return loss >60 dB single-mode (OS2, APC) and >30 dB multimode (OM3/OM4/OM5).
End-face geometry and cleanliness. Every fiber on the ferrule must make physical contact, so polish geometry (fiber height and ferrule angle) is controlled during production and checked by interferometry. Dust on any one fiber can raise loss on that lane, so clean and inspect MPO end faces before every mating; IEC 61300-3-35 is the common reference for end-face inspection criteria.
Testing. A properly built assembly is tested for insertion loss (and return loss for single-mode) on every fiber, with polarity verified. Every Huawellux product receives end-face visual inspection under a 400x video microscope and is tested for insertion loss (IL) and return loss (RL) before it ships. Interferometric end-face geometry (fiber height, coplanarity, end-face angle and radius) is checked by sample-based testing in standard production, and 100% interferometer testing of a batch is available on request. A formal test report is provided on request; state it in your RFQ.
How to Specify an MTP/MPO Cable
When you request a quote, include:
- Assembly type – trunk, patch cord, harness or cassette.
- Fiber count and format – MPO-8/12/16/24, legs per end.
- Fiber type – OM3, OM4, OM5 or OS2.
- Connector – MTP® brand or standard MPO, and loss grade.
- Gender per end – male (pinned) or female (unpinned).
- Polish – flat PC/UPC (multimode) or APC 8° (single-mode).
- Polarity – Type A, B or C.
- Length and jacket rating – e.g. LSZH, OFNR or OFNP.
- Labeling and test report requirements.
Frequently Asked Questions
What is an MPO cable used for?
An MPO cable connects 8 to 24 or more fibers in one connector. It is used for high-density data center backbones and for parallel-optic transceivers such as 100G SR4, 400G DR4, 400G SR8 and 800G DR8.
What does MPO stand for?
MPO stands for multi-fiber push-on: a connector that terminates a row (or rows) of fibers in one rectangular MT ferrule and latches with a push-pull action. For MTP® versus MPO, see MTP vs MPO.
Are MPO cables single-mode or multimode?
Both. MPO assemblies are built on OS2 single-mode and on OM3, OM4 and OM5 multimode fiber. Single-mode MPO is normally APC polished; multimode MPO-12 is normally flat polished. See OS2 vs OM3/OM4/OM5 and APC vs UPC.
Where can I read about MPO gender, fiber counts and polish?
Gender (pinned vs unpinned) is covered in male vs female MPO connectors, MPO-12/MPO-16 compatibility in MPO fiber counts, and polish in APC vs UPC.
Get MTP/MPO Cables Built to Your Specification
Huawellux manufactures MPO trunk cables, harnesses and patch cords at our factory in Shenzhen, with genuine US Conec MTP® or standard MPO connectors, each built to your fiber count, gender, polish, polarity and length, with per-assembly test reports. Send us your bill of materials or link design and our engineering team will check it for gender, polish and polarity consistency before production.
Dust caps are fitted on every connector, and a formal test report is available on request.
Huawellux replies to inquiries within 24 hours. Custom orders typically take 1–5 business days to complete production, with final timing confirmed case by case in the quotation. For special/custom requirements, MOQ is 2 km of fiber length. Standard listed patch cords have no formal MOQ. The sample fee is credited against the bulk order.
- Estimate quantities and lengths: Cable Estimator
- Ready to order: Request a Quote
MTP® is a registered trademark of US Conec Ltd.