Månadsvis arkiv: februari 2018
The continuous and rapid development of the Internet as well as the desire of people for higher speed optical networks facilitated the vigorous development of the entire optical communications industry and strongly promoted the independent R & D and innovation in many core technologies including optoelectronic devices technologies. 100g optical transceiver is regarded as the product of this big data era.
The first generation of 100G optical modules is CFP optical module with very large volume, then CFP2 and CFP4 optical modules appears. CFP4 optical module is the latest generation of 100G optical module, the width is only 1/4 of CFP optical module. Its package size is not same as the QSFP + optical module. The QSFP28 optical module has a smaller package size than the CFP4 optical module, which means the QSFP28 optical module has a higher port density on the switch. The following are several 100G QSFP28 series optical modules:
Main Types of QSFP28 Optical Transceivers
100G QSFP28 LR4 is a 100Gb/s transceiver module designed for optical communication applications compliant to 100GBASE-LR4 of the IEEE P802.3ba standard.
100G QSFP28 SR4 is a four-channel, pluggable, parallel, fiber-optic QSFP+ SR4 optical transceiver module for 100/40 Gigabit Ethernet, Infiniband DDR/EDR and 32GFC applications.
100G QSFP28 PSM4 is a four-channel, pluggable, parallel, fiber-optic QSFP28 PSM4 optical transceiver module for 100/40 Gigabit Ethernet and Infiniband DDR/EDR Applications.
100G QSFP28 CWDM4 is a 100Gb/s transceiver module which is designed for optical communication applications compliant with the QSFP MSA, CWDM4 MSA and portions of IEEE P802.3bm standard.
Of course, QSFP28 series also includes 100G QSFP28 active optical cables; these products have played an important role in the development of 100G.
Advantages of 100G QSFP28 Optical Transceivers
1. Power Consumption
The power consumption of QSFP28 typically is no more than 3.5W, while the power consumption of other 100G optical modules typically is between 6W and 24W. From this, the power consumption of QSFP28 optical modules is much lower power than other 100G optical modules.
Now the data center is mainly 10G network architecture, in which the interconnection solutions are mainly 10GBASE-SR optical module and duplex LC multimode fiber jumper. If the existing 10G network architecture based on the direct is upgraded to 40 / 100G network, it will save a lot of time and cost. Therefore, one of the major interconnection trends in data centers is to upgrade from 10G networks to 40 / 100G networks without changing existing duplex multimode infrastructure. In this case, the MPO / MTP branchable cable is undoubtedly the ideal solution for a 10G upgrade to 40 / 100G.
The QSFP28 uses the advanced 100G transport technology to provide the data center with a connection between the chassis switch and the core network, providing up to 150% greater panel bandwidth density than the 40G QSFP solution
Optical Module Test
When using optical modules, test performance is an essential step. Optical module is composed of transmitter and receiver, so when we test, it is generally divided into four steps, which mainly includes the transmitter and receiver test.
First, the transmitter part:
When testing, pay attention to the wavelength and shape of the transmitter output waveform, as well as the receiver’s jitter tolerance and bandwidth. When testing the transmitter, note the following:
1. The quality of the input signal used to test the transmitter must be good enough. In addition, the quality of the electrical measurements must also be confirmed by jitter and eye measurements. Eye diagram measurements are a common way to check the transmitter’s output waveform because the eye diagram contains a wealth of information that reflects the overall performance of the transmitter.
2.The output optical signal of the transmitter must be measured by the optical quality index such as eye pattern test, optical modulation amplitude and extinction ratio.
Second, the receiver part:
Unlike test transmitters, the quality of the optical signal must be sufficiently poor when testing the receiver that a light pressure eye pattern representing the worst signal must be created. This worst case optical signal must pass through jitter measurements and light Power test to calibrate.
1. Eye pattern test, this will ensure that the eye ”eye” is open. Eye diagram testing is usually done at the depth of the bit error rate;
2. Jitter test to test different types of jitter;
3. Jitter Tracking and Tolerance, testing the internal clock recovery circuit to track the jitter.
All in all, testing light modules is a complex undertaking, but it is also an indispensable step in ensuring good performance. Eye diagram measurement is a widely used measurement method that can effectively test the transmitter of an optical module. The optical module receiver test is more complex, but also requires more testing methods.
CWDM optical module adopts CWDM technology, which can combine optical signals with different wavelengths through an external wavelength division multiplexer. It saves fiber resources by transmitting through one optical fiber. At the same time, the receiving end needs to use the wave-demultiplexer to decompose the complex optical signal. In addition, CWDM optical modules can be plugged into switch or router SFP ports. This article will describe in detail what CWDM optical modules are and what are the differences between CWDM optical modules and other modules.
The Main Form Factors and Type of CWDM Optical Modules
There are three types of CWDM optical module form factors: SFP, SFP + and XFP. The transmission distance is generally as follows: 40KM, 80KM, 100KM, and 120KM.
CWDM optical modules can be divided into: CWDM SFP optical module, CWDM GBIC optical module, CWDM SFP + optical module, CWDM XFP optical module, CWDM X2 optical module, CWDMXENPAK optical module and CWDM LX-4 optical module.
The Differences between CWDM Optical Modules and Ordinary Optical Modules
CWDM optical modules are passive modules that do not emit laser. They generally use optical planar waveguide (PLC) technology; just a beam of light is divided into several beams of light. The ordinary optical modules belong to the photoelectric conversion device, which are active optical modules. Each module has two ports for receiving and transmitting, and the launch port inside is a laser.
CWDM Optical Modules VS DWDM Optical Modules: Which One to Choose?
The principle of DWDM optical modules is similar to CWDM optical modules, except that DWDM optical module are optical modules for dense wavelength division multiplexing, and has 40 common channels to choose from.
CWDM optical modules are widely used in schools, data centers, FTTH (Fiber to the Home), 1G and 2G Fiber Channel, metro Ethernet, security and protection systems and other fields.
DWDM optical modules are mainly used in long-distance optical synchronous digital transmission networks, such as Ethernet / Fiber Channel with 200km links and 80km links.
From a cost point of view, CWDM optical modules are cheaper than DWDM optical modules. CWDM optical modules provide a convenient and cost-effective solution for using Gigabit Ethernet and Fiber Channel.
DWDM optical modules, on the other hand, typically use denser channel spacing and are used for large optical networks over longer distances. If you want long-distance SFP modules, DWDM optical modules are the ideal choice.
The Differences between CWDM4 and PSM4
CWDM4 optical module transmission rate is 103.1Gbp, mainly used in computing, high frequency trading and other fields. Its cost is significantly higher than QSFP28 PSM4.
1. The optical transmitter: PSM4 needs four integrated silicon photonic modulator and a distributed feedback laser, and CWDM4 needs four CWDM direct modulation laser;
2. The connector: PSM4 needs a MPO connector with 8 fibers, CWDM4 needs duplex LC connector;
3. The optical fiber: PSM4 is a ribbon SMF (8 core), CWDM4 is a duplex SMF;
4. The transmission distance: PSM4 is 500 meters, CWDM4 is 2000 meters
5. The four wavelength of CWDM multiplexer: PSM4 does not need, but CWDM4 needs.
CWDM optical modules are multi-rate optical modules with 20-40km, 40-80km and 80-120km transmission distances. The optical modules of different wavelengths are marked with different colors to better meet customer requirements.
With the development of science and technology, the application of optical communications products in real life is becoming more and more widespread. The demand for network technology is also getting higher and higher. Therefore, 100G optical transceivers are gradually appearing on the market. The development of 5G and Data Center further make the 100G optical transceivers become the mainstream of the optical transceiver market gradually. Perhaps you have had a certain understanding of 100G optical transceivers, but if we analysis 100G optical transceivers from another point of view, you will find something different.
Development Background of 100G Optical Transceivers
For the earliest developed 100G optical transceiver, the form factor is CFP, developed in 2010. At that time, IEEE launched 100G optical transceiver SR10, LR4 and ER4 three standards, separately aiming at the 100m, 10Km and 40Km transmission. Followed by that, the IEEE standard added the new 100G SR4 project, but in 2013 did not reach consensus and vacancies. By 2016, the 100G optical transceivers used by various data centers were mostly the 25Gbps Serdes program, and the 100G optical transceivers that use the 50Gbps Serdes planned slowly appeared.
The Facing Problems for 100G Optical Transceivers
1. Channel Distance: The DWDM system supporting the 50GHz wavelength distance is very extensive. The 100G optical transceiver needs to meet the condition of supporting the 50GHz wavelength distance, therefore, the pattern of high spectral power should be used.
2. OSNR (optical signal-to-noise ratio): Under the same pattern, 100G optical transceivers requires10dB higher than 10G optical transceivers and 4dB higher than 40G optical transceivers. Therefore, a low OSNR tolerance code and high coding gain FEC algorithm are needed.
3. CD Margin: Under the same conditions, 100G optical transceiver dispersion tolerance only needs 1/100 of 10G optical transceiver, accounting for 16/100 of 40G optical transceiver. Therefore, 100G optical transceivers can use dispersion compensation technology, in the electric field or the optical domain compensation to complete the dispersion compensation for each wavelength.
4. PMD Tolerance: Under the same conditions, PMD (polarization mode dispersion) tolerance of 100G optical transceiver is 1/10 of 10G optical transceivers, accounting for 4/10 of 40G optical transceiver, so you need to choose coherent reception plus digital signal processing.
5. Nonlinear Effects: Compared with 10G / 40G optical transceiver, the nonlinear effects of 100G optical transceivers are messier.
The Types and Advantages of 100G Optical Transceivers
The main form factors of 100G optical transceiver include: CFP, CFP2, CFP4 and QSFP28. To compare their advantages, the main factor to consider is the costs and power consumption for Data Centers.
1. CFP optical transceiver supports all C-band wavelengths tunable and can complete the link detection, which use a common optical dual-binary modulation format ODB, convenient layout, power consumption is less than 24W.
2. The volume of CFP2 optical transceiver is one-half of CFP, its integration is 2 times CFP. It can complete the wide dynamic input range based on SOA to achieve stable admission sensitivity, support a full CFP optical transceiver, its low power consumption is lower than 9W.
3. The volume of CFP4 optical transceiver is one-half of CFP2, its integration is twice that of CFP2, front panel port density is also doubled compared with CFP2. CFP4 optical transceiver follows the MSA protocol, support the same rate as CFP/CFP2. Its transmission power increases significantly, but the power consumption drops significantly, only about half of the original, the system cost is lower than the CFP2. In addition, CFP4 optical transceiver uses 4 * 25 forms, through the 4 * 25G channel, complete 100G transmission. The transmission power is higher with higher stability.
4. The form factor of QSFP28 optical transceiver is smaller than the CFP4 optical transceiver. QSFP28 optical transceiver power consumption is generally not more than 3.5W, the use of QSFP28 optical transceiver can directly upgrade from 25G to 100G not through 40G, and therefore the cost is lower.
|Types||Standard||The Largest Transmission Distance||Connector||Channel||Wavelength||Fiber Types|
(CFP4 doesn’t support SR10)
Learning the contents of the 100G light module, above, do you have any further information? From the development trend, QSFP28 optical transceiver and CFP series optical transceiver are 100G network hot solutions, and the use of CXP will be less and less. Gigalight, as a veteran optical transceiver manufacturer with professional technology, advanced R & D capability and stable manufacturing capability, not only has many popular 100G optical transceiver products, like 100G QSFP28 CWDM4, 100G QSFP28 PSM4, CFP2 100G LR4, and etc. but also will release more new 100G optical transceivers in the first quarter of this year. More information about 100G optical transceivers, please visit the official website.
Mobile communication is an important driving force for the development of optical networks. It is also self-evident that the development of optical modules is of great importance. We know that the optical module market can be subdivided into the Telecom market, the Datacom market and the Access market. Among them, the Telecom market is the ”main battlefield” competed by the optical module industry. The biggest surprise for the future Telecom market is the evolution of 5G technology. Based on the requirement of 5G higher rate, higher capacity and higher base station density, there will be greater new demand and market space for high rate optical modules.
The Demands of Optical Transceivers for 5G Network
Although the current 5G is still in the standard stage, major equipment manufacturers have actively carried out joint trials with operators to strive to achieve 5G commercial use by 2020. ”5G is commercial, carrying is the first.” It is predicted that the future number of 5G base stations will exceed 10 million, which will bring the surge in demand for optical modules in quantity. Compared with 4G technology, 5G data transmission rate is 10 to 100 times that of 4G, which means that the number of optical modules used by a single base station will increase substantially when the optical module rate remains unchanged.
We simply use a formula to represent the demand of a 5G optical module: optical module requirement (F) = base station number (m) * single base station module requirement (n). In the 5G era, compared with 4G, m and n will be significantly improved. Therefore, under the 5G construction period, the optical module will become one of the most flexible segments in the 5G industry chain. In addition, the demand for optical modules for the construction of large-scale data centers will also increase with the outbreak of 5G traffic.
To sum up, it is helpful for optical module suppliers to get ahead in the 5G era when they grasp the demand for optical modules in 5G networks in advance. So what are the specific demands of 5G optical modules? What are the mature products in the industry can initially meet the needs of 5G load? We try to analyze in the following parts.
Why Will the 100G Optical Transceivers Become the Mainstream for 5G Network?
Compared with 4G networks, 5G rebuilds the BBU into a separate architecture of CU (Centralized Unit) and DU (Distributed Unit), so its bearer needs an additional layer of intermediate network. Fronthaul – middlehaul – backhaul, the three carrier network requirements for optical modules are different. For 5G fronthaul, the CPRI bandwidth per 10MHz single-antenna port is about 614.4Mbps under ideal transmission conditions. The typical 5G wireless bandwidth is 100M ~ 1G, the peak is 20G, the antenna port may be 64 or 128. After a simple conversion, 5G fronthaul network granularity should be 25Gbps, which has been generally accepted by the industry. It can be inferred that the future 50Gbps and 100Gbps of the 5G pre-transmission modules will be the mainstream. For 5G middlehaul, it will use DWDM ring network structure, transmission distance 10 ~ 40km, n * 25G technology. This means that 100G optical modules are highly likely candidates for 5G messenger. For 5G backhaul, either with the network can be merged, but also separate. According to the future OTN networking, n * 100G technology will be adopted; if there is no OTN networking and 200G / 400G optical module technology. But no matter what kind of technology, 100G and above ultra-high-speed optical module must become the mainstream for the 5G market.
In conclusion, the demand of the 100G optical module by the 5G network is very urgent. At present, there are many kinds of mature 100G optical transceivers in the market, like 100G QSFP28 CWDM4, 100G QSFP28 PSM4 and 100G CFP / CFP2 / CFP4 optical modules provided by Gigalight. They cover the mainstream form factors: CFP / CFP2 / CFP4 / QSFP28 and can be used for a variety of optical network bearer demand. In particular, 100G QSFP28 and 100G CFP4 have the advantages of more compact, high module integration, transmission efficiency, power consumption and cost-effectiveness.