Author: Fiber-MART.COM

by http://www.fiber-mart.com

Key words: Fiber optical media converter, industrial media converter, optical transceiver module, fiber optical cables, fiber optical jumpers

In general, the optical power of fiber media converter or optical modules is as following: multi-mode is between -10db ~ -18db; single-mode 20 kilometers is between -8db ~ -15db; and single-mode 60 kilometers is between -5db ~ -12db between. But if the optical power of the fiber media converter is between -30db ~ -45db, then it seems that there is a quality problem with the fiber optic transceiver. So, how to judge whether there is a quality problem with the fiber media converter?

First, check whether the indicator light of the optical fibermedia converter and opticaltransceivermodule and the indicator light of the twisted pair port are on

a. If the optical port (FX) indicator light of the optical media converter is off, please make sure whether the optical fiber link is cross-linked? One end of the fiber jumper is connected in parallel; the other end is connected in cross mode.

b. If the optical port (FX) indicator light of the fiber A media converter is on and the optical port (FX) indicator light of the B fiber media converter is off, the fault is at the A fiber media converter. A possibility is that the optical transmitting port of the A fiber media converter (TX) is broken because the optical port (RX) of the B fiber media converter cannot receive optical signals; another possibility is that the optical fiber link of the optical transmitting port of the A fiber media converter (TX) has a problem (optical cable or fiber jumper may be broken)

c. If the Twisted Pair (TP) indicator light is off. Please make sure whether the twisted pair connecting line is wrong or the connection is wrong? Please use a continuity tester to test (but the twisted-pair indicator light of some fiber media converter will only turn on after the fiber link is connected).

d. Some fiber media converter have two RJ45 ports: (ToHUB) indicates that the cable connecting the switch is a straight-through line; (ToNode) indicates that the cable connecting the switch is a crossover line.

e. There is an MPR optical switch on the side of some fiber media converters which means that the connection line to the switch is a straight-through line. And the DTE optical switch is means that the connection line to the switch is a crossover line.

Whether the fiber optic cable and fiber jumper are broken

a. Fiber optical cable broken test: using a fiber optical laser tester to test one end of the optical cable connector or coupler, and watching if there is visible light at the other end. If there is visible light, it indicates that the optical cable is not broken.

b. Optical fiber jumper broken test: using a Visual Fault Locator test one end of the fiber jumper, and watching if there is visible light at the other end. If there is visible light, it indicates that the fiber jumper is not broken.

Is the half/full duplex mode wrong?

There is an FDX optical switch on the side of some media converters. It means full duplex; HDX optical switch means half duplex.

4. Detect with optical power meter

The optical power of the optical fiber media converter or optical tranceiver module under normal conditions is between -10db ~ -18db for multimode; between -8db ~ -15db for single mode 20 km; between -5db ~ -12db for single mode 60 km. If the optical power of the fiber media converter is between -30db ~ 45db, then it can be judged that the fiber media converter is with quality problem.

The above is the relevant introduction on how to judge whether there is a problem on optical fiber media converter. As the optical fiber market continues to mature, the application field of optical fiber becomes more and more extensive. With the widespread use of optical fiber, it is natural that there will be failures. But as long as we find out the cause and solve it accordingly! 

by http://www.fiber-mart.com

Key words: MPO trunk cables, MTP jumper, MPO/MTP adapter, MPO/MTP patch panel

With the widespread deployment of data centers, the demand for 400G solutions is growing. The rapid increase in the number of network links will result in the data center space of traditional optical fiber cabling being cramped and difficult to manage. The application of MPO optical fiber connector/optical fiber jumper is based on this demand, which can accommodate the optical cable connection of high-speed and large-capacity optical communication system to meet the 400G high-speed transmission demand.

MPO (Multi Push On) is a type of multi-core optical fiber connector. Usually 12-core optical fiber is arranged in a row. It can support one or more rows of optical fibers in the same MPO connector. According to the number of cores discharged in the connector, it is divided into one row (12 cores) and multiple rows (24 cores or more) .The size of the MPO connector is the same as that of the SC connector, but the density is increased several times, which greatly saves the space occupied by the line ports and cables, so as to achieve higher density cabling in a certain space. Great flexibility and scalability also make cabling deployment easier and more adaptable to the needs of future network upgrades, expansions and changes. It has been widely used in optical fiber communication networks, high-density data centers, transmission systems and CATV networks, and more and more applications in active optical cable assemblies, such as AOC, QSFP, etc.

fiber-mart.com also designed high-density MPO/MTP patch panels, fiber optical distribution boxes, and rack chassis to installed with MPO trunk cables. The MPO trunk cable is with push-pull rod designed. In high-density and small environments, it is very inconvenient to operate, especially for jumpers in these intermediate spaces. The push-pull rod design of MPO patch cord can solves this problem.

by http://www.fiber-mart.com

Nowadays, with the development of network technology, many friends who need to use the network will use the switch, which can realize the common use of multiple computers in a network. Nowadays, commonly used switches are mainly divided into  commercial network switches and industrial Ethernet switches. In order to meet the flexible and changeable industrial environment and anti-interference aspects, there is a particularly large gap between industrial switches and commercial switches. In contrast, the functions of industrial switches are more practical. So, what are the differences and advantages of industrial Ethernet switches compared with commercial network switches? Today, UnitekFiber will share with you some information about them.

There is no essential difference between industrial switches and commercial switches in terms of data link layer, network layer, protocol layer, etc., but for the real-time requirements of industrial control, industrial Ethernet switches solve the real-time communication, network security, and intrinsic safety. Technical issues such as safety and explosion-proof technology, and adopt some measures suitable for industrial environment, such as waterproof, anti-vibration and so on.

1. The differences in appearance between industrial switch and commercial switch

Industrial switche generally use a fanless enclosure fan mode, and basically use a metal enclosure, which has higher strength. commercial switche generally use a plastic enclosure with higher strength and use a fan cooling mode.

2. The differences in application environment between industrial switch and commercial switch

Industrial switches can adapt to a low temperature of 40°C to 85°C, and have excellent dust and humidity resistance. The protection level is above IP40. The scope of application is more common, and it can be installed and used under any dangerous conditions. Generally speaking, the operating temperature of ordinary switches is between 0°C and 50°C, and they have basically no dust and moisture resistance, poor protection level, and have POE power management functions.

3. The seivice life is different between industrial switch and commercial switch

The service life of industrial switch is generally more than 10 years, while the service life of commercial switches is only 3 to 5 years. The difference in service life is related to the maintenance of the middle of the project. Therefore, generally speaking, it is in parks and office buildings. For video transmission in network surveillance environments such as parking lots and those environments where high-definition video output is required, industrial switches or switches whose performance needs to be comparable to those of industrial grade should be used.

The operating voltage of industrial switches is different from that of commerical switches. Industrial switches can be limited to DC24V, DC110V, Marvel/AC220V, while commerical switches can only work under AC220V voltage, and industrial switches are mostly in ring network mode. Reduce line use and maintenance costs.

Conclusion: Whether in terms of components, mechanical environment, climate environment or electromagnetic environment, working voltage, power supply design, installation method, and heat dissipation method, the performance of industrial Ethernet switches is better than that of commerical switches. However, when we purchase the switch, you must consider the working environment and other aspects in detail. In short, if your industrial control site environment is very harsh, then you must use industrial grade Switch, if the environmental requirements are not high, you can choose commercial ordinary switches.

by http://www.fiber-mart.com

To realize the internal optical network interconnection of data centers, optical transceivers are indispensable. As the number of ports and density increase, half of the cost of optical networks in data centers will be occupied by optical transceivers. At present, 100G interconnection technology has been widely adopted in the newly-built data centers of major Internet companies, and 400G interconnection technology will be commercially available on a large scale in the next 2 to 3 years. Therefore, the implementation technology of 400G optical transceiver has become the focus important part of the industry.

According to this progress, ultra-large-scale data centers are expected to start deploying 400G Ethernet in 2020, and 400G Ethernet will enter the large-scale deployment phase in about 2022.

Early 400G optical transceivers used 16-channel 25Gbps NRZ implementations (such as 400G-SR16), and used CDFP or CFP8 packages. The advantage is that it can borrow the mature 25G NRZ technology on 100G optical transceivers, but the disadvantage is that 16 signals are required for parallel transmission, and the power consumption and volume are relatively large, which is not suitable for data center applications.

In the current 400G optical transceiver, 8 channels of 53Gbps PAM4 (400G-SR8, FR8, LR8) or 4 channels of 106Gbps PAM4 (400G-DR4, FR4, LR4) are mainly used on the optical port side to achieve 400G signal transmission, and used on the electrical port side 8 channels of 53Gbps PAM4 electrical signals, using OSFP or QSFP-DD packaging. Both OSFP and QSFP-DD packages can provide 8 electrical signal interfaces. In comparison, the QSFP-DD package size is smaller (similar to the QSFP28 package of the traditional 100G optical transceiver), which is more suitable for data center applications; the OSFP package size is slightly larger, because it can provide more power consumption, so it is more suitable for telecommunications application.

In terms of optical wavelength, 400G optical transceiver can be divided into multi-mode (MM) and single-mode (SM); in terms of signal modulation methods, they are divided into NRZ and PAM4 modulation (currently PAM4 is the mainstay); distinguished from transmission distance, 400G optical transceivers can be divided into SR, DR, FR, LR; from the packaging form, 400G optical transceivers can be divided into CDFP, CFP8, OSFP, QSFP-DD, etc.

400G CFP8 Optical transceiver

CFP8 is an expansion of CFP4, the number of channels is increased to 8 channels, and the size is correspondingly increased to 40*102*9.5 mm^3. Using 16x25G parallel signals to quickly complete the market and application of 400G products. However, the cost is relatively high, and 16x25G lasers are needed, or a PLC splitter is used to reduce the number of lasers, but the LOSS of the splitter is too high, which directly causes the laser’s emission power to be relatively large, and the cost will also be high. The power consumption is also high, the panel interface density is too low, and the size is large.

400G OSFP Optical Transceiver

The full English name of OSFP is Octal Small Formfactor Pluggable, Octal refers to 8, which means that 56G electrical signals, 8*56GbE are used directly, but 56GbE signals are formed by 25G DML lasers under PAM4 modulation . This standard is a new interface standard and is not compatible with the existing photoelectric interface. OSFP comes with a heat sink, its size is 100.4*22.58*13 mm^3, which is much smaller than CFP8, and its power consumption is relatively low. The maximum is only 15W, but it is slightly larger than QSFP-DD, which requires a larger area PCB board.

400G QSFP-DD optical Transceiver

Q in QSFP-DD refers to “Quad”, which means 4 channels, each QSFP56 is 4*56Gbe, forming a 200G signal; DD refers to “Double Density”, there are two QSFP56 in parallel, 2*200G generation The 400Gbe signal, the full name is Quad Small Form Factor Pluggable-Double Density, this solution is an expansion of QSFP, adding one row to the original 4-channel interface to 8 channels. It is smaller in size than OSFP and compatible with existing 40GbE QSFP and 100GbE QSFP28 interfaces. The original QSFP28 transceiver can still be used. You only need to insert another transceive to achieve a smooth upgrade. Due to the addition of 4 channels, the pins of the upper and lower sides of the electrical interface are increased by one row.

400G COBO Optical Transceiver

COBO is the abbreviation of “consorTIum for on board opTIcs”. The reflector module is directly placed on the PCB board, no longer limited by the front panel interface density. At the same time, the heat dissipation problem can be greatly relieved by reusing the powerful heat sink between the PCB boards. This optical transceiver is small in size. Since t is not hot-swappable, once a optical transceiver fails, the entire board business needs to be stopped and the board need to be taken out, which is very inconvenient.

The optical interconnection network of the data center is facing the transition from 100G to 400G, and technologies for different application scenarios are also competing with each other. As a key hardware device for optical network interconnection in future data centers, 400G optical transceiver also faces challenges in terms of speed, power consumption, volume, and cost.

by http://www.fiber-mart.com

In the 5G era, the demand for optical cables is the most prominent problem encountered in the deployment of 5G fronthaul networks. The demand for 5G fronthaul bearer solutions is growing rapidly. In order to reduce the consumption of optical fiber resources, passive wavelength division schemes have been widely used.

Wavelength division multiplexing (WDM), including CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing), etc. Refers to the coupling of multiple signals of different wavelengths on a single fiber for simultaneous transmission. It has multiplexers and demultiplexers. The multiplexer (MUX) combines multiple signal wavelengths in one optical fiber at the transmitting end; the demultiplexer (DEMUX) transmits multiple wavelengths in one optical fiber at the receiving end. The signals of each wavelength are separated. The main purpose of wavelength division multiplexing is to increase the available bandwidth of optical fibers, which can be expanded through WDM without the need to lay more optical fibers. Therefore, it is widely adopted by telecommunications companies.

What is the difference between CWDM and DWDM?

Tje wavelength intervals of CWDM and DWDM is different

CWDM: Wavelength interval ≥ 20nm, usually 8 bands from 1260~1620nm, 20nm interval;

DWDM: Wavelength interval <10nm, usually 1528~1560nm band, wavelength interval is 200GHz (1.6nm), 100GHz (0.8nm) or 50GHz (0.4nm),

The Modulated lasers of CWDM and DWDM are different

Under normal circumstances, CWDM modulated lasers use uncooled lasers, while DWDM uses refrigerated lasers. Cooled lasers use temperature tuning, and uncooled lasers use electronic tuning.

What are the advantages of CWDM vs DWDM?

Compared with DWDM, the biggest advantage of the CWDM system is its low cost. The cost of the device is mainly reflected in filters and lasers. The wide wavelength interval of 20nm makes CWDM have low requirements on the technical indicators of the laser. The structure of the optical multiplexer/demultiplexer is simplified, so the cost is lower.

DWDM is suitable for long-distance transmission. Compared with CWDM, DWDM with tighter wavelength spacing can carry 8 to 160 wavelengths on an optical fiber, which is more suitable for long-distance transmission. With the help of EDFA (Erbium doped fiber amplifier), DWDM system can work within thousands of kilometers.

What is CCWDM?

After knowing what is CWDM and DWDM, let us understand a mini version of CWDM-CCWDM. What is the difference between it and CWDM?

CCWDM is called a compact coarse wavelength division multiplexer, which is a mini version of CWDM. It is based on the wavelength division multiplexing technology of TFF (thin film filter) and works in the same way as CWDM. The difference is that adjacent channels of CCWDM use parallel beams to cascade in free space instead of optical fibers. Without the optical fiber used for cascading, the size of the CCWDM package box is 10 times smaller than the standard CWDM package.

What is the difference between CWDM and CCWDM?

The CWDM system uses a low-cost, non-cooling distributed feedback (DFB) laser, while the CCWDM’s collimator and filter are welded on a common substrate, and the cascade structure of the two is different.

A three-port filter used for a specific wavelength of CWDM. Its wavelength channel is composed of two lenses and a TFF matched to the specific wavelength. The reflection port of each filter is connected to the common port of the next filter, and the filters are connected by optical fiber connectors, which is a CWDM multiplexer.

The principle of CCWDM is to use the input lens to focus the optical signal with wavelength λ1, λ2…λn on the input fiber to the first filter; the optical signal with wavelength λ1 passes through the first filter and is coupled to the first output lens In the first output fiber, the optical signal with a wavelength of λ1 is separated; the remaining optical signals are reflected by the first glass slide to the next slide for optical signal separation; and so on, until all the signals are separated. The coupling between the wavelength channels is realized in the form of straight rays that follow the “Zigzag” route.