An MPO-16 cable has one row of 16 fibres in a single connector, which gives the eight transmit and eight receive fibres that SR8 and DR8 parallel optics use. Its key sits differently from MPO-12, so the two cannot be mated. Radix Fibrotech builds MPO-16 assemblies in multimode or APC single-mode, as trunks, patch cords or breakouts.
What an MPO-16 cable is
An MPO-16 connector holds 16 fibres in a single row, numbered 1 to 16 along the ferrule. Cables carrying it are also sold as MTP-16, the branded version with a floating ferrule. The reason for 16 fibres is the lane count of the optics: eight lanes each way need eight transmit fibres and eight receive fibres, which is 16 in total. A 12-fibre connector cannot carry that on one plug, and a 24-fibre connector would leave eight fibres idle.
The connector exists to serve parallel optics at 400G and 800G. Duplex optics keep using LC connectors, and optics with four lanes each way keep using eight fibres on an MPO-12.
Optics that use a 16-fibre connector
| Optic | Fibre type | Fibres | Note |
|---|---|---|---|
| 400GBASE-SR8 | Multimode | 16 | Eight lanes each way |
| 800GBASE-SR8 | Multimode | 16 | Eight lanes each way, 850 nm |
| 800GBASE-DR8 | Single-mode | 16 | APC end face; some modules instead use two 12-fibre connectors |
The module datasheet, not the line rate, sets the connector. Some 800G modules have one MPO-16 port, others have two MPO-12 ports with eight fibres each, and other 800G optics use duplex LC. Check the port on the exact module before ordering cable. The 400G and 800G parallel optics guide compares the cabling options side by side.
MPO-16 compared with MPO-12
| Feature | MPO-12 | MPO-16 |
|---|---|---|
| Fibres in the connector | 12 | 16 |
| Rows | One | One |
| Key position | The established MPO position | Different, so it cannot be mated with MPO-12 |
| Typical parallel optics | 40G and 100G SR4, 400G DR4 (8 fibres used) | 400G and 800G SR8 and DR8 (all 16 used) |
| Guide pins | Pinned (male) or unpinned (female) | Pinned (male) or unpinned (female) |
| Adapters and cassettes | 12-fibre parts | 16-fibre parts only |
The practical effect is that existing MPO-12 adapters, panels and cassettes cannot be reused for a 16-fibre link. Existing MPO-12 trunks can still serve optics that use two 12-fibre ports, or 400G DR4-class links on eight fibres. A 16-fibre link needs 16-fibre hardware at every connection in the channel.
APC polish for single-mode MPO-16
Single-mode MPO connectors use an angled end face (APC, 8 degrees) so reflected light is steered into the cladding instead of back to the laser. DR8 channels are built on APC, and both sides of every mated pair must be APC. Multimode MPO-16 uses a flat polish. An angled and a flat ferrule do not meet properly, so the pair loses light and can be damaged.
Single-mode connectors are sensitive to dirt because the core is 9 µm across. Inspect each end face on delivery and before every mating, and clean with a tool sized for a single-row 16-fibre ferrule. The difference between flat and angled polish is explained in the UPC vs APC guide.
Fibre map and polarity at 16 fibres
On a direct parallel link, the fibre map matters more than the polarity letter. Parallel optics usually put the transmit lanes on one half of the row and the receive lanes on the other. If the transmit fibres sit at positions 1 to 8 and the receive fibres at 9 to 16 on both modules, a reversed mapping is needed: position 1 to 16, 2 to 15, and so on to 8 to 9. Each transmit fibre then lands on a receive position at the far end.
A straight mapping (1 to 1) is used where a cassette or a second reversal elsewhere in the channel corrects it. Get the transceiver's published fibre map, put the required end-to-end mapping on the drawing, and have it confirmed in the quote. A wrong mapping does not damage anything, but the link will not come up.
Breakouts and conversion assemblies
Several 16-fibre jobs are really conversions between port types. Common builds, each made to drawing:
- MPO-16 to two MPO-12. An 800G port feeds two 400G ports, each on eight fibres, usually APC for single-mode.
- MPO-16 to eight duplex LC. Splits the link into eight channels for cassettes or test sets.
- MPO-16 to MPO-16 trunk. The permanent link between 16-fibre panels or cassettes.
The leg lengths, stagger and fibre-to-position mapping must be on the drawing. See MTP MPO breakout cables for the construction options.
What to send us for a quote
- Assembly type: trunk, patch cord, or breakout, and the connector at each end.
- Fibre count (16), and the leg split for breakouts.
- Grade: OM4 or other multimode, or OS2 single-mode.
- Connector and gender: MTP or MPO, female or male at each end.
- End face: flat for multimode, APC for single-mode.
- Fibre map or polarity, with the transceiver datasheet reference.
- Length for each line, tolerance, and leg lengths.
- Jacket, colour, and outer diameter limit.
- Quantity per line, label text, and test report format.
Send the list through the quote request form, or email sales@radixfibrotech.com with a sketch of the channel.
Questions buyers ask
Is MPO-16 the same as MTP-16?
MPO is the connector type and MTP is a branded, enhanced version of it with a floating ferrule. They mate with each other. A drawing that says MPO-16 can normally be built with MTP-16 connectors.
Can an MPO-16 plug into an MPO-12 adapter?
No. The key position differs, so the two cannot be mated. Use 16-fibre adapters and cassettes, or a conversion assembly that has MPO-16 at one end and MPO-12 at the other.
Does every 800G link need MPO-16?
No. Some 800G modules use two MPO-12 ports, and others use duplex LC. MPO-16 is for modules with one 16-fibre port. Read the module datasheet and confirm the connector before ordering.
Should MPO-16 for 800G be APC or UPC?
Single-mode MPO-16 is APC, as used by DR8 optics. Multimode MPO-16 for SR8 optics has a flat polish. Never mate an angled connector with a flat one.
Can I run 800G over my existing OM4 plant?
Possibly, for multimode SR8 optics. Reach at 800G is shorter than at 100G, so check route length against the optic's datasheet and IEEE 802.3. The connectors also have to change, because MPO-12 hardware does not fit a 16-fibre port.
How do I order an MPO-16 breakout to two 400G ports?
Specify an MPO-16 on the 800G side and two MPO-12 connectors on the 400G side, with eight fibres in each. Give grade, end-face polish, gender, leg lengths and the fibre map for each leg.