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首页 > Home > Application Notes > How To Select MPO Patch Cords And MPO Adapters For 40G & 100G Parallel Transmission Optical ModulesHow To Select MPO Patch Cords And MPO Adapters For 40G & 100G Parallel Transmission Optical Modules
Time: 2024-01-17
Common 40G and 100G multimode & single-mode parallel transmission optical modules on the market include 40G-SR4/PSM4 and 100G-SR4/PSM4. After purchasing these modules, how should customers select MPO patch cords and MPO adapters for network deployment? In practical applications, how do we manage and match the polarity of MPO patch cords for these optical modules?
The TIA-568 standard provides clear definitions for MPO patch cord and MPO adapter types.
MPO Patch Cord Types
There are three wiring sequence definitions for MPO patch cords (Array Connector Cable Type): Type A, Type B, and Type C.
Figure 1 MPO Patch Cord Types A/B/C
• Type A (Key up–Key down): Straight-through patch cord using a straight fiber bundle. The two ends have MPO connectors (one key up, one key down), with identical fiber positions at both ends.
• Type B (Key up–Key up): Full-cross patch cord using a reversed fiber bundle. Both ends use key-up MPO connectors, with completely reversed fiber positions at the two ends.
• Type C (Key up–Key down): Pair-wise cross patch cord using a cross-pair fiber bundle. The two ends have MPO connectors (one key up, one key down), with each adjacent fiber pair at one end reversed at the other end.
MPO Adapter Types
MPO adapters (Array Adapter Type) are used to connect two MPO patch cords and are available in Type A and Type B:
• Type A: Key up–Key down matching at both ends
• Type B: Key up–Key up matching at both ends
Figure 2 Connection Diagram for Parallel Signals – Method 1
When networking with parallel transmission optical modules such as 40G‑SR4/PSM4 and 100G‑SR4/PSM4, MPO patch cords are connected from the modules, then linked to external MPO backbone cables through MPO adapters for transmission. There are two common connection methods, with corresponding fiber configurations shown in the table below:
Table 1 Line Configuration
|
Connection Method
|
MPO Backbone Cable Type
|
MPO Adapter type
|
MPO Patch Cord Type
|
|
1
|
Type A
|
Type A
|
One Type A and one Type B
|
|
2
|
Type B
|
Type B
|
Type B
|
Connection Method 1
A typical connection diagram is shown below. Two MPO-interfaced optical modules can be connected as transceiver endpoints on the left. The modules connect to a Type A MPO adapter via one Type A and one Type B MPO patch cord respectively, then link into the Type A MPO backbone cable to complete optical polarity management.
The end-face type of MPO patch cords can be 0° flat (UPC) or APC angled, depending on and matching the end-face type of the MPO interfaces on the optical modules.
Figure 3 Connection Diagram for Parallel Signals – Method 1
Connection Method 2
A typical connection diagram is shown below. Fiber polarity management in this method is simpler: only Type B MPO patch cords, Type B backbone cables, and Type B adapters are used.
Important note: Since Type B adapters use a key up‑to‑key up structure, the MPO patch cords at both ends must have 0° flat end faces and cannot be APC angled.
Figure 4 Connection Diagram for Parallel Signals – Method 2
In short, when networking with QSFP‑SR4 or QSFP‑PSM4 parallel modules:
• Option 1: Use Type A backbone cables + Type A MPO adapters + one Type A and one Type B patch cord
• Option 2: Use all Type B patch cords and backbone cables + Type B MPO adapters
Polarity matching in the first method can be confusing to manage, while the second method is much more convenient. For this reason, most customers choose Type B MPO patch cords for parallel optical modules.
Two simplified interconnection schemes can also be derived for QSFP‑SR4 / QSFP‑PSM4 parallel optical modules:
1. Direct interconnection between two modules using only one patch cord: A Type B patch cord is mandatory.
2. Interconnection between two modules using two patch cords + one MPO adapter:
• Two Type B patch cords + one Type B adapter
• Two Type A patch cords + one Type B adapter
• One Type A patch cord + one Type B patch cord + one Type A adapter
Moduletek provides a full series of 40G and 100G multimode & single-mode parallel transmission optical modules, as well as multimode & single-mode MPO patch cords in all wiring sequence types. Welcome to inquire and place orders.
For further inquiries about the above content, please contact us at: sales@moduletek.com
