MPO connector is a multi-core connector. Its core component ferrule is different from ordinary single-core connectors such as SC, LC, FC, and ST. It use a multi-core MT ferrule.
MT ferrule is a multi-core, plastic optical communication passive device (6.4×2.5 mm square end face, 0.25 mm hole pitch), widely used in MTP MPO Cable assembly and AOC cable, 12 core and 24 core are the most commonly used type.
MT ferrule types
There are many types of MT ferrules. In addition to the number of cores, they are also divided into single-mode, multi-mode, low-loss, and brand. The MT ferrules used for 40G optical modules or 100G optical modules are all multi-mode ferrules.
As the most commonly used MT ferrule in the market, SENKO 12F MT ferrule has the advantages of ease of use and ultra-low insertion loss. Industrial-grade low loss, single-mode/multi-mode insertion loss is ≤0.25dB (typical value <0.1dB), exceeding the IEC 61755-3-31 Class B standard. Quality, price, durability and easy assembly make the 12F solution your best choice.
The 8-core ferrule indeed is a 12-core ferrule, and the middle 4 cores are dummy fibers and not used. The 8-core multimode ferrule is widely used in 40G, 1 core is 10G, and 8 cores are 40G. Because the optical module has both receiving and transmitting, the 8-core optical fiber are divided into 4 cores for transimitting signals, and 4 cores receiving signals. So 1 core is 10G transimission rate and 4 cores are 40G transimission rate. The same structure for 100G optical transceivers.
The 24F MT ferrule adopts a double-row 12-hole high-precision structure to achieve industry-leading high-density connection and ultra-low insertion loss performance. It is available in single-mode (SM), multi-mode (MM) and low-loss multi-mode (Low Loss MM) versions, and is an ideal choice for 100G/400G parallel optical platforms. SM 24F and MM 24F must be used with a 20N high-force spring. 100G transmission system is always use a 20-core multi-mode MT ferrule.
With the demand for high-speed upgrades, the latest MT 16/32F ferrule has emerged by SENKO. Its design meets the new TIA604-18 standard, which is for the MPO 16 connector hole pitch specification. There are two specifications: single-row 16F and 32F (2X16F). The multimode version can be used for 100G/400G parallel optical applications, requiring the use of special guide pins designed for 16F and 32F, using the new standard of 5.3mm guide pin spacing.
MT Ferrule Optical Parameters
| MT | MM Standard | MM Low Loss | SM Standard | SM Low Loss |
| Insertion Loss | ≤ 0.75dB | ≤ 0.35dB | ≤ 0.75dB | ≤ 0.35dB |
MT ferrule application in optical modules
If it is a 40G QSFP+ SR4 MPO patch cord, it is generally pre-terminated with a MPO 12 fiber connector or 8 fiber MPO connector (MT multimode ferrule). 4 Channels for optical transmission, 4 channels for optical signal receving.
| Fiber number | Lane assignment |
| 1 | RX0 |
| 2 | RX1 |
| 3 | RX2 |
| 4 | RX3 |
| 5 | Not used |
| 6 | Not used |
| 7 | Not used |
| 8 | Not used |
| 9 | TX3 |
| 10 | TX2 |
| 11 | TX1 |
| 12 | TX0 |
If it is a QSFP28 SR4 100G MPO cable, it is generally pre connectorized with a MPO 24 connector (24 cores MT ferrule). And the optical transceivers connected will be 100GBASE SR4 QSFP transceiver. The channels that are not used are left blank, and are generally described as Unused in English.
