In the optical communication industry, especially high-rate optical modules, great attention is paid to the high performance and stable quality of the device, as the core components in the field of communication and data communication, laser diodes, optical components (OSA), optical modules and other optical components in the transmission, collection, display, storage and processing of information play a crucial role. Among them, multiple optical components in the optical module, including fiber array units, coupled lenses, optical isolators, collimators, couplers and separators, and other focusing and switching optical devices must be precisely calibrated, while each component must be highly integrated and permanently bonded to each other to ensure long-term reliability, through multiple processes throughout the production process. The need to use a variety of adhesives and thermal conductivity materials, which requires very high material expertise.

1. Chip mounting

The packaging process of optical modules Can be roughly divided into three types: TO Can, Box and COB. Among them, COB (Chip on Board) package sticks the bare chip to the interconnect substrate with conductive adhesive or non-conductive adhesive, and then performs lead bonding to achieve electrical connection and drive the chip to work. This kind of package is also widely used in data center optical modules. Conductive adhesives (silver adhesives) are widely used in the optical communication industry for chip-level assembly. The compact structure design of the optical module and the iteration of high-power chips and lasers, multiple devices gather together to generate heat dissipation challenges, and the temperature rise of the device will affect the stable operation of the chip and laser, and eventually lead to the failure of the optical module. According to statistics, the higher the operating temperature of the optical module, the higher the failure rate, so the heat dissipation capacity, working temperature, bonding performance, etc. of the conductive adhesive will affect the reliability of the chip and laser.

2. Lens coupling

Optical device coupling is to divide or combine the optical power of the same wavelength. It is mainly used to transmit signals and realize photoelectric conversion of models. It can also be understood as aligning light with certain devices, such as coupling light into an optical fiber or coupling different lights. Optical coupling is a key process in the packaging process of optical devices and optical modules, which controls the loss of optical power and affects the performance of optical modules. The laser chip emits the light, turns it into focused light through the optical lens, and introduces the Z-maximum light energy into the fiber to achieve fiber transmission. However, the optical module space is small, in order to ensure the consistency of the optical module performance, the optical fiber and the optical path must complete the high-precision coupling. Since the optical coupling accuracy is often required to be within 3 microns, the curing shrinkage, moisture absorption and thermal expansion coefficient of the glue are critical.

3, optical path packaging

The optical path adhesive is used to bond and fix the splitter plate and part of the lens surface in the optical module, and it requires good optical performance. Optical modules often run uninterrupted during the working process, especially for 400G high-rate optical modules, optical path transmission requirements, low volatiles of devices and equipment and long-term, stable and efficient operation requirements are higher. Therefore, the packaging material requires excellent bond strength, low curing shrinkage, low CTE, etc., to meet the harsh environment such as high and low temperature cycle and cold and thermal shock, to prevent the expansion or contraction of chemical materials from causing stress damage to the optical module, which affects the skew of the optical module device or excessive optical path loss.

4. Pigtail assembly

Pigtails are also called bare optical fibers. One end of the pigtails has an optical fiber connector, and the other end is a broken end of the optical fiber core. The end of the optical fiber connector is used to connect the device, and the broken end of the optical fiber core is fused with the broken end of other optical fiber cores to achieve minimum insertion loss.

5. Fill the bottom

The bottom of the BGA chip on the optical module mainboard needs to be filled with glue to seal and protect the solder joints, so that the BGA package has higher mechanical reliability. The process requires that the bottom filling glue curing speed is fast, less than 10min, high solid content, low VOC volatilization, to prevent volatiles from causing optical path abnormalities.

6. Electromagnetic shielding

With the development of high-rate optical modules in the direction of miniaturization, low power consumption, high speed, long distance and intelligence, low-rate optical modules have gradually failed to meet the daily data transmission needs, and the transmission rate requirements of data centers and telecom operators are becoming higher and higher. The higher the speed of the optical module, the higher the frequency of the electromagnetic wave radiated out, the electromagnetic environment of the optical module is complex, and the need to avoid electromagnetic interference in the work can not be ignored.

7. Thermal management

As the pace of 5G gets closer and closer, the development of user needs and data centers, low speed has slowly been unable to meet the daily data transmission needs, optical modules as the core optical electronic equipment, the two most important development directions in the future, high speed and miniaturization, will face increasing heat dissipation problems. Optical fiber communication has become the main transmission way of network information because of its advantages of large transmission capacity and good confidentiality. As one of the most important devices in optical fiber communication system, optical module is widely used in wide area network (WAN), metropolitan area network (MAN), local area network (LAN) and other fields. As a core optical electronic device, optical modules are also facing increasing requirements in terms of their complexity and diversity, two of which are important aspects, namely, high speed and miniaturization. The miniaturization of optical modules will bring one of the thorniest problems, which is heat dissipation. Too many devices are accumulated together, which will inevitably bring the heat of the device is difficult to dissipate, and the heat dissipation difficulty causes the device to heat up, resulting in changes in the working state of the chip, and in serious cases, it will cause the chip to stop working.

C-Light transceivers: Guaranteed Material

·All material BOMs used are subject to system control and customer supervision, eliminating arbitrary changes and replacements.

·Both core drivers and optical chip suppliers are large listed companies both domestically and internationally.

·Only authorized agents from top brands such as Murata are selected for electronic materials.

PON stick is a network communication device. It is mainly used for access to the broadband network in the home or enterprise, and is one of the main equipment for optical fiber access to the home. The function of the PON stick is to convert the optical signal transmitted by the optical fiber into an electrical signal, and then connect to the computer, router, TV and other equipment through the network cable to achieve network access and transmission.

There are two main types of PON sticks: GPON and EPON. GPON stick is a kind of PON stick based on GPON technology, which can provide more stable and high-speed network transmission, and is widely used in China. EPON stick is a PON stick based on EPON technology, which has a slightly lower transmission rate compared to GPON, but its cost is lower.

The installation and use of PON stick is relatively simple, only need to plug in the optical fiber interface, power supply, network cable can be used. However, it should be noted that the ONU needs to be fixed on the wall or the location of the fixed place during installation, and it is necessary to avoid direct light to the ONU, so as not to affect its normal work.

In short, PON stick is a necessary network access equipment, it can provide users with more high-speed, stable network transmission services, for the user's home or enterprise network construction is of great significance.

Can PON Stick replace ONU dial-up

PON stick and ONU dial-up are both connected to the network through optical fiber, but their working principle and use are different, so they cannot be completely replaced. After connecting to the network through optical fibers, you need to connect an optical modem to convert optical signals into electrical signals, and then connect to a computer or router through a network cable to access the Internet. The PON stick integrates the functions of the ONU into a small device, which can be directly connected to a computer or router through a USB interface, so as to achieve Internet access.

PON stick has certain advantages over ONU dial-up Internet, such as small size, easy to carry, easy to use and so on. However, the performance and function of the PON stick is relatively weak, suitable for some simple Internet access needs, and for high-speed, large traffic network applications, ONU dial-up Internet access is still a more stable and reliable choice.

Therefore, PON stick and ONU dial-up Internet have their own advantages and disadvantages, can not be completely replaced. The Internet access method depends on the actual requirements and usage scenarios.

If it is in the optical broadband access mode, some operators provide PON stick this device, can replace the traditional ONU dial-up Internet access, to achieve direct optical access to the computer or router. The working principle of the PON stick is similar to that of the ONU, but because of its small size and good portability, it can access the optical fiber network and provide network services anytime and anywhere, which is very convenient to use. At the same time, the PON stick can also be connected to a wireless router to achieve wireless network coverage.

However, it is important to note that not all operators offer PON sticks, and the performance and functionality of PON sticks are also different from traditional ONU, and may not be able to meet some special needs. Therefore, when choosing to use PON stick or ONU dial-up Internet access, you need to choose according to your actual situation.

In addition, it should be noted that when using PON stick or ONU dial-up Internet access, you need to comply with the network usage regulations of the operator and relevant laws and regulations to avoid network anomalies or penalties caused by illegal operations.

PON ONU Stick's Application

PON ONU Stick refers to a miniaturized ONU product packaged in SFP/SFP+, Built-in optical modem switching chip, supporting MAC address configuration management and communication protocol conversion. Mainly used on the Ethernet optical port of Ethernet switches to achieve interconnection and interoperability between Ethernet switches and ONT networks. After connected, the Ethernet switch where the optical modem is located becomes an ONT terminal device in the OLT network.

The advantage of using ONU stick is that it can save the space and power supply conditions of traditional optical modem access. Due to the SFP encapsulation of the ONU stick, flexible networking of Ethernet protocol switches, routers and other terminal equipment such as CPE can be easily and quickly implemented through the PON ONT network.

Through testing and verification, C-Light's XGSPON and XGPON ONU stick series products can effectively realize the interconnection and interoperability of OLT equipment such as ZTE, Huawei, FiberHome, BDCOM, Bell,CALIX, ADTRAN and other brands of Ethernet optical terminal equipment.

PON ONU Stick's typical application case

This case is that the XGSPON/GPON combo PON service card on a domestic 6xx series OLT switch is interconnected with the XGSPON optical ONU stick and XPON ONU stick in the 10G/1G optical port of a foreign 2900 series Ethernet switch through the OLT SFP and splitter. The application case of connecting CPE 2900 series Ethernet device to PON broadband network through uplink OLT device is realized. At this time, the C-Light's XGSPON and XPON ONU slicks must first be compatible with the 2900 series switching device, and at the same time, they must be found and recognized by the 6xx OLT that is linked, and then registered into the OLT system. Then C-Light's ONU stick also needs to support the common network application functions of customers, such as Sn management registration; Omcc; MOCl; Imgpv2; Vlan.