There is an interesting phenomenon that multimode fibers are more expensive than single-mode fibers but the transceivers are the reverse. That is because the multimode core diameter is large and easy to align with VCSEL lasers and detectors while the single mode fiber cable is very hard to build and align transceiver components with and requires very expensive alignment equipment. Therefore, multi-mode transceivers are less expensive than single-mode transceivers. Now the 100G Ethernet network has been widely applied in data centers and there are various types of 100G fiber optic transceivers available on the market. Is there a type of 100G single-mode transceiver which can provide a low-cost solution for long-reach data center optical interconnects? The answer is Yes. The 100GBASE-PSM4 (parallel single-mode 4-lane) QSFP28 transceiver can do that.
Overview of 100GBASE-PSM4 QSFP28 Transceiver
The 100GBASE-PSM4 QSFP28 transceiver supports 100G link over eight single-mode fibers (four fibers for transmit and four fibers for receive) with data transmission distance up to 500 meters. It uses four parallel lanes for each signal direction and each lane carries 25G optical signal. In addition, the 100GBASE-PSM4 QSFP28 transceiver is structured with MTP/MPO interface, so it is usually used with single-mode fiber ribbon cable with MTP/MPO connector.
Working Principle of 100GBASE-PSM4 QSFP28 Transceiver
The figure below shows the working principle of the 100GBASE-PSM4 QSFP28 transceiver. The transmitter side accepts electrical input signals compatible with common mode logic (CML) levels, wile the receiver side converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels. All data signals are differential and support a data rate up to 25Gbps per channel.
Applications of 100GBASE-PSM4 QSFP28 Transceiver
The 100GBASE-PSM4 QSFP28 transceiver can be used for 100G to 100G connection. As the following figure shows, two 100GBASE-PSM4 QSFP28 transceivers are plugged into Host IC, then these two transceivers are connected by MTP/MPO patch cord and MTP/MPO patch panel.
From an optical transceiver module structure viewpoint, PSM uses a single uncooled CW laser which splits its output power into four integrated silicon modulators. Therefore, the 100GBASE-PSM4 QSFP28 transceiver can be used for 100G to 4x25G connection. As the following figure shows, the 100GBASE-PSM4 QSFP28 transceiver and four 25G-LR SFP28 transceivers are connected by MTP-LC breakout cable.
The 100GBASE-PSM4 QSFP28 transceiver meets the requirement for low-cost 100G connections at reaches of 500 meters in applications that fall in between the IEEE multi-wavelength 10 kilometers 100GBASE-LR4 single-mode fiber approach and its multimode-fiber based 100GBASE-SR10 short reach specifications. It can support a link length of 500 meters over single mode fiber cable, which is sufficient for data center interconnect applications.
As high density cabling system has been widely deployed, MTP/MPO cable can be easily found in network deployment. But when you buy MTP/MPO cable in the online store, you must have been encountered with the situation where you not only have to select single-mode or multimode, 12 fibers or 24 fibers, but also have to consider the outer jacket of the cable which can protect the cable from damage. According to different cabling environment, there are different types of outer jackets, among which CMP, LSZH, CMR, CM are mostly used. How much do you know about them? This article will decode outer jacket of MTP/MPO cable and I hope it will be helpful for you when buying MTP/MPO cable.
CMP (plenum-rated) cable complies the IEC (International Electrotechnical Commission) 60332-1 flammability standard. It has passed stringent burn testing and is suitable for installation into air plenum spaces, where environmental air is transported. Typical plenum spaces are between the structural ceiling and the drop ceiling or under a raised floor. CMP cable is designed to restrict flame propagation no more than five feet as well as limit the amount of smoke emitted during the fire. In spite of this, for safety reason, any high-voltage equipment is not allowed in plenum space because the fresh air can greatly increase the danger of rapid flame spreading if the equipment is on fire. Because it has high fire-retardant, it usually costs more than other types.
The LSZH (low smoke zero halogen, also refers to LSOH or LS0H or LSFH or OHLS) has no exact IEC code equivalent. The LSZH cable is based on the compliance of IEC 60754 and IEC 61034. It is the newest in a family of ratings and it is sometimes refereed to as low toxicity cable. Containing no halogen type compounds that forms these toxic substances, LSZH cable gives of very little smoke and does not produce a dangerous gas/acid combination when exposed to flame. LSZH cable is suitable to be used in place where air circulation is poor such as aircraft, rail cars or ships. However, it is less fire-retardant than CMP.
CMR And CM
CMR (riser-rated) complies IEC 60332-3 standards. CMR cable is designed to prevent fires from spreading floor to floor in vertical installations. It can be used when cables need to be run between floors through risers or vertical shafts. CM (in-wall rated) cable is a general purpose type, which is used in cases where the fire code does not place any restrictions on cable type. Some examples are home or office environments for CPU to monitor connections.
To select a suitable MTP/MPO cable for your network deployment, it is necessary to learn about the relevant details of cable ratings, which is as important as other factors. As a professional MTP patch cable supplier, FS.COM provides high quality plenum and LSZH MTP/MPO patch cord at affordable prices.