company news about Simple Guide to Distinguish MPO/MTP Polarity

                                                                      Simple Guide to Distinguish MPO/MTP Polarity

Nowadays, many data centers are migrating into the 40G and 100G transmission.

To prepare for this change, MPO/MTP technology is applied to meet the requirements of high-density patching. Typically, a fiber optic link needs two fibers for full-duplex communications. Thus the equipment on the link should be connected properly at each end. However, high-density connectivity usually requires more than two fibers in a link, which makes it more complex to maintain the correct polarity across a fiber network, especially when using multi-fiber MPO/MTP components for high data rate transmission. Therefore, many technicians would prefer to use pre-terminated MPO/MTP components designed with polarity maintenance for easier installation. This article will specifically guide you to understand the polarity of MPO/MTP products and the common polarization connectivity solutions.

Could you ensure that the signal transmitted from any of the active equipment can be directed to the receive port of the next active equipment? Or Are you crazy like explain to customers about Polarity many times, at last, they said, so sorry, I am still confused. Please follow Amerian's customer standards

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In order to ensure MPO/MTP systems work with correct polarity, experts develop three methods that will be presented in this paper. We want to introduce Polarity A and B, which are our usual standard and widely usage. 

What Is Polarity?

Keeping the right polarity is essential to the network. A transmit signal from any type of active equipment will be directed to the receive port of the second piece of active equipment and vice versa. Polarity is the term used in the TIA-568 standard to explain how to make sure each transmitter is correctly connected to a receiver on the other end of a multi-fiber cable. Once the component is connected to the wrong polarity, the transmission process will be unable to go on.

Structure of MPO/MTP Connector

When discussing about the polarity, MPO/MTP connector is an important component for you to know. An MPO/MTP connector has a key on one side of the connector body. There are two positions of the key — key up or key down. Key up position means that the key sits on top. When the key sits on the bottom, it is the key down position. Moreover, the fiber holes in the connector are numbered in sequence from left to right named as P1 (position 1), P2, etc. Each connector is additionally marked with a white dot on the connector body to designate the P1 side of the connector when it is plugged in. The MPO/MTP connector can be further divided into female connector and male connector. The former has no pins while the latter has two pins on the connector. The following picture shows the basic structure of MPO/MTP connector.

Connecting Methods of A, B

The TIA standard defines two types of duplex fiber patch cables terminated with LC or SC connectors to complete an end-to-end fiber duplex connection: A-to-A type patch cable is a cross-version and A-to-B type patch cable is a straight-through version. Based on this, there is three polarity connecting methods for MPO/MTP products. Here will introduce them in detail.

Type A is the most straight-forward method

To better understand Polarization Method A, the Type A Trunk Cable should be first introduced which is also referred to as straight cable. It is a straight-through cable with a key up MPO/MTP connector on one end and a key down MPO/MTP connector on the opposite end, which makes the fibers at each end of the cable have the same fiber position as shown in the following figure. For instance, the fiber located at position 1 (P1) of the connector on one side will arrive at P1 of the other connector, and the fiber located at P12 on one side will arrive at P12 on the other side.

As for Polarization Method A, it always works with the Type A trunk cable that is designed to connect MPO/MTP modules on each side of the link. The connectivity Method A is also shown in the following figure for your reference.

Type B is the “cross-over” occurred in the cassette.

Type B truck cable is used to connect the two modules on each side of the link. Clearly different from Type A trunk cable, Type B trunk cable uses two key up connectors on both ends of the cable, which is known as reversed cable. This mating structure results in an inversion, which means the fiber positions are reversed at each end. For example, the fiber at P1 of one end is mated with the fiber at P12 of the opposing end. From the following figure, you can learn the fiber sequences of a 12 fiber Type B cable and the connectivity Method B.

From the above screenshot, we're sure will help customers to know about MPO/MTP Systems Work with Correct Polarity, because these days many customers don't understand much about Polarity, which leads to the bulk produce progress, our engineers are confused about customers usage.

Polarity also is the meaning of the Fiber sequence. If the customers don't understand the meaning of Polarity, we also can support the scheme of fiber sequence, or through customers' usage habits. Usually, Type B is the normal standard for customers. If the customer with special demands, Type A we also can do for you.

If the customer confirms the wrong polarity, also not be worried. Just told him, change the position and direction of the LC fiber patch cord based on his usage habit.