The development of artificial intelligence and Internet of things presents new challenges to the expansion of data centers, and there is often a contradiction between technology and cost. In order to realize high density and high capacity, it is important to control cost factors and reasonable wiring. In the wiring, we can choose the high-speed cable and the optical transceiver cables, so how do we choose these two products in the actual scene? What are the differences and what advantages do they have? Let's study together about the differences between 10G SFP+ DAC and 10G SFP+ transceivers.
As a transmission medium, 10G SFP+ DAC and 10G optical transceivers can be selected. What is the difference between the two?
The 10G DAC is a copper cable designed with SFP+ connectors on both ends and is less expensive than a 10G optical transceiver.
The use of 10G DAC wiring is more flexible, transmission distance up to 15 meters, in the actual construction process is less difficult to operate.
10G DAC cabling saves on connected devices, eliminating the need for patch panels, and servers and network equipment can be directly connected to TOR switches, which indirectly save on input costs.
If the vertical distance of the wiring does not exceed the cabinet, 10G DACs can be used for the connection. When the distance between the TOR switch and the network switch is greater than 15M, multimode optical fibers and fiber transceivers can be selected. Usually, OM3/OM4 LC fiber jumpers and 10G SFP+ optical transceivers are used. In other words, 10G SFP+ optical transceivers are widely used in long-distance transmission.
Gigalight provides high-speed direct connection solutions for data center interconnection, including 10G SFP+ to SFP+ high-speed cable solutions, which not only reduces power consumption, but also increases network scalability. Want to learn more about the product details? You can visit our website.
Optical transceiver consists of optoelectronic devices, functional circuits, and optical interfaces. The optoelectronic devices include transmit and receive parts. The transmitting part is: Inputting a certain bit rate of the electric signal is processed by an internal driver chip to drive a semiconductor laser (LD) or a light emitting diode (LED) to emit a corresponding rate of modulated optical signal, and an internal optical power automatic control circuit is provided therein. The output optical signal power remains stable. The receiving part is: After a certain code rate of the optical signal input transceiver is converted into an electrical signal by the light detecting diode. After the preamplifier outputs the corresponding rate of the electrical signal, the output signal is generally PECL level. At the same time, an alarm signal will be output after the input optical power is less than a certain value.
Today Gigalight will share with everyone some tips on using optical transceivers if you usually pay attention to the maintenance of the optical transceiver. Note that the following two points can help you reduce the loss of the optical transceiver and improve the performance of the optical transceiver.
1. There are CMOS devices in this chip. Pay attention to prevent static electricity during transportation and use.
2. The device grounding should be good, reduce parasitic inductance.
3. As far as possible manual welding, if you need to paste, control the reflow temperature cannot exceed 205℃.
4. Do not lay copper below the optical transceiver to prevent the impedance from changing.
5. The antenna should be away from other circuits to prevent radiation efficiency becomes lower or affect the normal use of other circuits.
6. The transceiver should be placed as far away from other low-frequency circuits, digital circuits.
7. It is recommended to use magnetic beads for the isolation power of the transceiver.
1. Do not look directly into the optical transceiver that has been inserted into the device (whether it is a long-range or short-range optical transceiver) with naked eyes, and avoid eye burns.
2. When using a long-distance optical transceiver, the transmit optical power is generally greater than the overload optical power. Therefore, it is necessary to pay attention to the length of the optical fiber and ensure that the actual received optical power is less than the overload optical power. If the length of the optical fiber is short, use a long-range optical transceiver and use it with light attenuation. Be careful not to burn out the optical transceiver.
3. To better protect the optical transceiver from cleaning, it is recommended that you plug the dust plug when it is not in use. If the optical contact is not clean, it may affect the signal quality, it may also lead to link problems and error codes.
4. Rx/Tx, or arrow in and out directions is generally marked on the optical transceiver to facilitate identification of the transceiver. Tx at one end must be connected to Rx at the other end, otherwise the two ends cannot be linked.
Read the above notes, whether do you have a new understanding of the use of optical transceivers? It is important to be helpful to everyone and thank you for your support and attention to Gigalight. For more product details, please visit our official website.
With the commercial use of cloud computing, big data and other new technologies, data center flow and bandwidth have an index incensement. According to the LightCounting forecast, by 2019, the sales volume of data center optical transceivers will be over $50 million and the market scale is hopeful to reach $4.9 billion, which will be a huge opportunity for optical transceiver vendors. At the same time, we can see that there are some difference in applications of optical transceivers between data center and Telecom. In the post, we will discuss the technology development direction of data center optical transceivers in detail.
On the macro level, the data center optical transceiver market is a market that reasonably defines the life and working conditions of optical transceivers according to the actual requirements, and fully optimizes the market for the cost performance of optical modules. Due to the open trend of several networks, this market has the characteristics of positivity and open, welcoming the characteristics of new technologies and the atmosphere of exploring new standards as well as application conditions. All of these provide excellent conditions for the development of data center optical transceiver technology. Here we are trying to enumerate the development direction of some data center optical transceiver technology for your reference.
Non-hermetic Package
As the cost of optical components (OSA) accounts for over 60% of the cost of optical transceivers, and the space for cost reduction of optical chips becomes smaller and smaller, the most likely cost reduction is the packaging cost. While ensuring the performance and reliability of optical transceivers, it is necessary to promote the packaging technology from the expensive hermetic package to the low-cost non-hermetic package. The key points of the non-hermetic package include the non-air tightness of the optical device itself, the optimization of the design of the optical components, the packaging materials and the improvement of the process. Among them, optical devices, especially lasers, are the most challenging. This is because if the laser device is not hermetic, expensive hermetic package is not needed. Fortunately, in recent years several laser manufacturers have avowed that their lasers can be applied to non-airtight applications. In view of the large number of shipping data center optical transceivers, most of them are mainly non-hermetic package. It seems that the non-hermetic packaging technology has been well received by the data center optical transceiver industry and customers.
Hybrid and Integrated Technology
Under the drive of multi-channel, high speed and low power consumption demand, the same volume optical transceivers need to have more data transmission, and the photonic integration technology gradually becomes a reality. Photonic integration technology has a broader meaning: for example, based on the integration of silicon-based (planar optical waveguide hybrid integration, silicon photonics, etc.), based on the integration of indium phosphide. The hybrid and integrated technology usually refers to the integration of different materials. There are also the construction of partially free space optics and partially integrated optics called hybrid integration. The typical hybrid integrated active optical devices (laser, detector, etc.) are integrated into the passive optical path connection or some other function (points or wave, etc.) of the substrate (planar optical waveguide and silicon light, etc.). Hybrid integrated technology of optical components can be done very compactly, complying with the trend of miniaturization of optical transceivers, easy to use mature IC encapsulation process automation. It is beneficial to mass production, which is an effective technical method for recent data center optical transceivers.
Flip Chip Technology
Flip chip is a high-density chip interconnection technology from IC packaging industry. In the rapid development of optical transceivers today, the interconnection between short - shrinking chips is a valid option. It is better to weld optical chip directly onto the substrate through gold-gold welding or eutectic welding, which is much better than the high frequency effect of gold wire bonding (short distance, small resistance, etc.). In addition to the laser, the heat generated by the laser is easily transferred from the solder to the substrate due to the proximity of the source area to the solder, which is helpful for improving the efficiency of the laser at high temperature. Because the backward welding is the mature technology of IC packaging industry, there are many kinds of commercial automatic reverse welding machines used in IC packaging. Optical components require optical path coupling, so the accuracy requirements are high. These years optical components processing with high precision inversion welding machine are very eye-catching and in many cases have realized the passive light, greatly improving the productivity. Due to the characteristics of high precision, high efficiency and high quality, the flip chip technology has become an important technology in the data center optical module industry.
Chip On Board Technology
COB (chip on board) technology also comes from the IC packaging industry, whose principle is through the rubber patch technology (epoxy die bonding) to fix chips or optical components on the PCB, and then gold wire bonding (wire bonding) uses electrical connection, and lastly drip glue sealing on the top. Obviously, this is a non-hermetic package. The advantage of this process is that it can be automated. For example, the optical components can be viewed as a "chip" after it has been integrated by back loading and welding. Then the COB technology is used to fix it on the PCB. At present, COB technology has been widely adopted, especially in the use of VCSEL arrays in short distance data communication. The integrated silicon photonics can also be packaged by using COB technology.
Silicon Photonics Technology
Thh silicon photonics is a technology that discusses the technology and technique of optoelectronic devices and silicon-based integrated circuits, and a science integrated into on the same silicon substrate. Silicon photonics technology will eventually go to photoelectric integration (OEIC: Opto - Electric Integrated Circuits), making the current separated photoelectric conversion (optical transceivers) into local photoelectric conversion of photoelectric integration, further pushing the system integration. Silicon photonic technology can certainly do a lot of things, but for now it's the silicon modulator. From the industry, the threshold of a new technology into the market must be the performance and cost is competitive and the need for huge upfront costs of silicon photonics technology is really a big challenge. The data center optical transceiver market, due to the large demand concentration within 2 kilometers, with the strong requirements of low cost, high speed and high density, is suitable for a large number of applications of silicon photonics.
In my opinion, the traditional 100G optical transceivers have been very successful, and they are not easy to get a lot of silicon photons. However, at the rate of 200G or 400G, since the traditional direct modulation type is close to the limit of bandwidth, the cost of EML is relatively high, which will be a good opportunity for the silicon photonics. The large number of applications of silicon photons also depends on the openness and acceptance of technology in the industry. If taking into account the characteristics of silicon photonics when setting the standards and agreements or relaxing some indicators (wavelength, extinction ratio, etc.) on the premise of meeting the transmission condition, they will greatly promote the development and application of silicon photonics.
On Board Optics
If OEIC is the ultimate photoelectric integration scheme, on board optics is a technology between OEIC and optical transceivers. On board optics moves the photoelectric conversion function from the panel to the motherboard processor or to the associated electrical chip. By saving space and increasing the density, it also reduces the distance of the high frequency signal, thus reducing the power consumption. On board optics is primarily focused on the short-range multimode fiber used in the VCSEL array, but recently there is a scheme for using silicon photonic technology in single-mode fiber. In addition to the composition of the simple photoelectric conversion function, there are also the forms (co-package) that encapsulate the photoelectric conversion function (I/O) and the associated electrical chip (processing). Although on board optics has the advantages of high density, the manufacturing, installation and maintenance costs are relatively high, and are currently used in the field of supercomputing. It is believed that with the development of technology and the need of the market, on board optics will gradually enter into the field of optical interconnection of data center.
In the past few years, Telecom operators have already upgraded their LTE networks by using additional spectrum, carrier aggregation and LTE-A, and have added Small Cell in Macrocell coverage area to drive the increasement of fronthaul bandwidth requirements. In the current, many operators and equipment vendors have standardized the multi-rate transceivers that support 10Gb/s for all fronthaul requirements. Because they are able to meet most of different transmission speed requirement by one device and decrease the complexity of the specific site design and spare part inventory. Many operators, especially those that lease their fronthaul fiber, also deployed WDM system in their fronthaul networks.
5G Fronthaul Will Need Faster Optical Products, But How Fast?
With the emergence of 5G mobile network, the fronthaul demand will also change. The target peak bandwidth of 5G is 20Gb/s, which will require a higher spectrum than LTE to realize the requirement. That is to say, the shorter wavelength can realize the smaller antenna in the millimeter wave range, thus allows the use of higher order MIMO antenna arrays. In LTE area, 4*8 and 8*8 MIMO have been top. But in 5G area, 64*64 MIMO is also possible. The number of MIMO is higher; the bandwidth required for the corresponding fronthaul link is larger. In the case that other conditions are same, the second way for 5G to increase bandwidth is to use 100 GHz frequency (LTE uses 20GHz), so that can produce a single radio transmission from cellular site to the core network for more than 5 times of bandwidth.
Given the fronthaul bandwidth required to support 5G radio may be have a substantial growth, mobile device manufacturers update the CPRI specification to "eCPRI" (released in August 2017). One key factor of eCPRI is to transfer some physical layer signal processing from the baseband unit to the radiofrequency pull head (RRH), which in many cases reduces the fronthaul bandwidth to one in ten.
When all the different factors that influence the bandwidth of the 5G fronthaul add up (some drive its growth, some drive it down), the expected bandwidth fall in the 14 Gb/s to 30 Gb/s range, depending on the eCPRI implementation details, base stations, and etc. If the old CPRI scheme is adopted, all physical layer signal processing will remain in the baseband unit, and similar 5G network configuration will require 236Gb/s fronthaul bandwidth. As a result, the 5G base station will generate 160Gb/s or more in nominal terms, and with eCPRI, the actual fronthaul bandwidth required will be 14-30Gb/s.
Just like that 10G optical transceivers can become the actual standard for LTE fronthaul, the next generation of higher standard Ethernet speeds will be applied to 5G fronthaul, which means that 5G deployment will require a large number of 25GbE devices. Even though some components are industrial temperature and/or bidirectional versions specially designed for fronthaul application.
5G Network Will Also Need Higher-speed Optics Products( 25Gb/s or above)
Mobile fronthaul or backhaul need 50G, 100G or even 400G optical transceivers. CPRI alliance has defined fronthaul for a long time, but there is no a consistent definition for wireless backhaul. LightCounting defines the backhaul as the first optical link that begins in BBU and carries the flow from the core network. Other broader definitions include access, aggregation, and core networks. Naturally, if the data flow from BBU to the core network flows to 25Gb/s, then 50G, 10G, or even 400Gb/s transfers may be needed.