Optical devices are the basic components of optical fiber communication systems. China's research and production in the field of optical devices are not too late. Whether they are active devices or passive devices, they all meet the needs of scientific research or engineering in the early development stage of optical fiber communications in China. However, over time, due to the weak industrial foundation, inadequate scientific research, and institutional and mechanical reasons, the gap between China's optical devices in terms of core technology and high-end products and foreign advanced levels has become increasingly prominent.
Optical active device 1. Development Overview Optical active devices are key components in the optical communication system that convert electrical signals into optical signals or convert optical signals into electrical signals, and are the heart of optical transmission systems. Devices that convert electrical signals into optical signals are called light sources, mainly semiconductor light emitting diodes (LEDs) and laser diodes (LDs). Devices that convert optical signals into electrical signals are called photodetectors, mainly photodiodes (PINs) and avalanche photodiodes (APDs). In recent years, optical fiber amplifiers have become a rookie of optical active devices. Currently, a large number of applications are erbium-doped fiber amplifiers (EDFAs). Raman optical amplifiers are being researched and are very promising.
The study of optical active devices in China began in the 1970s. At that time, western countries imposed high-tech blockades and embargoes against China in accordance with the so-called "Patriot rule," and light active devices were also included. So the Institute of Semiconductors, the Wuhan Institute of Posts and Telecommunications, the 44th Department of the Electronic Department, the 13th Department of the Electronic Department and other units carried forward the spirit of “self-reliance†and developed a so-called short-wavelength optical device with a wavelength of 850nm. For example, GaAlAs/GaAs materials were used. LD and LED light sources, Si-PIN detectors, etc., in the form of a kink or heterojunction. Although the performance of these devices is now poor, it also satisfies the needs of China's initial stage of optical communications.
Since then, these units have developed so-called long-wavelength devices with wavelengths of 1310 nm and 1550 nm, such as semiconductor lasers using buried InGaAsP/In buried dual-structures, PIN detectors using InGaAs/In materials, and the like. The performance of these chips has been greatly improved, but in the initial stage of development, epoxy bonding between the chip and the optical fiber is used. Therefore, the device has poor airtight properties, low bonding strength, and easy displacement of the optical fiber, and thus the entire device. The performance and reliability are poor. Later, a fully metallized coupling packaging process was adopted, which greatly improved the reliability and lifetime of the device, which met the growing needs of optical communications at that time.
Before 1993, China’s optically active components required for optical communications were basically provided by domestic manufacturers. As a result, Western countries recognized the need to use “Batumi†for technical blockade and bans in China in active devices and other areas. However, losing the big market in China was not worth the candle. Therefore, it was only necessary to announce the dissolution of "Batum" and foreign optical active devices began to flood into the Chinese market.
2. Industry Status With the rapid development of optical communication technology, the technical requirements for optical active devices have become higher and higher. Although the relevant units in China have made great efforts to track the world trend and achieved breakthroughs in quantum well semiconductor materials and device technology, the level of laboratories for advanced devices such as distributed feedback (DFB) semiconductor lasers have also greatly improved, but due to the input of human resources. The material resources are far from sufficient, and the gap with the advanced level in foreign countries is becoming increasingly prominent.
3. Market Overview According to the investigation of some manufacturers, the production and sales of China's optical active devices from 1998 to 2000 are shown in Table 1. As can be seen from the table, in 2000, the sales of optical active components of these manufacturers were 649,000 (of which about 193,000 were exported and 456 thousand were domestic sales), and the total sales amount was 470 million yuan, an increase of 94.2% over 1999. .
Regarding the market situation of the national optical active devices in 2001, there are different estimates. Some think that it is 1.1 billion yuan, of which the market share of the optical transceiver (light source-detection) integrated module is 40%, the DWDM laser is 39%, the pump laser is 20%, and the optical amplifier is 1%. Some think that it is 1.4 billion yuan, of which the market share of optical transceiver modules is 36%, 36% for DWDM lasers, 14% for pump lasers, and 14% for optical amplifiers. It is expected that light active devices will grow at a rate of 40-50% over the next few years, of which market sales in 2002 will increase by more than 70% from 2001.
It is estimated that domestically produced optically active devices only account for 30-40% of the domestic market.
Optical passive device 1. Development Overview Optical passive devices are devices in the optical communication system that need to consume certain energy and have certain functions without optical-electrical or electrical-optical conversion, including optical fiber connectors, fiber couplers, wavelength division multiplexers, and optical switches. Optical attenuators and optical isolators are the joints of optical transmission systems. Optical connectors are the most widely used and most widely used devices in optical passive devices, followed by couplers and wavelength division multiplexers, and other devices use less. With the development of optical communication technologies, the demand for dense optical wavelength division multiplexers and large port number matrix optical switches will gradually increase.
Research on optical passive devices in China began in the late 1970s with the advent of fiber optic technology. At that time, the connection of optical fibers was one of the six major issues that must be resolved in optical fiber communications. In addition, problems such as shunting, switching, and wavelength multiplexing must be resolved. So, the 23rd Department of Electronics, Wuhan Institute of Posts and Telecommunications, and the 34th Institute of Electronics, and other units “started from scratchâ€, dedicated to the study of all-fiber structures and discrete component combinations (micro-optical devices), developed optical fiber medium-sized Multi-mode optical fiber connectors, splice type and fusion taper type optocouplers and mechanical optical switches meet the needs of short- and long-wavelength multimode fiber communication studies at the time.
Since then, optical communications have entered the single-mode long-wavelength phase and started to be used in large numbers. As optical passive devices are not only more technically demanding, they are also increasing in number and are urgently required for industrialization. In the optical connector, APT optical fiber connector (1.78mm diameter) connector production line was first introduced to meet the needs of the initial development of single-mode optical communication in China. Afterwards, with the success of mass production technology of ceramic casing, the quality of the optical connector has been further improved, and it is easy to assemble. Therefore, there are many companies that have assembled connectors for parts production. In the area of ​​fiber couplers, the introduction of microcomputer-controlled fusion taper devices has made coupler production simpler; more gratifyingly, through theoretical research and practical exploration, various broadband products can be produced on the same equipment. Couplers and two-wavelength wavelength division multiplexers have excellent product performance, thus forming an optocoupler industry. Most of the optical connectors and optocouplers used in current optical communication systems in China are domestically produced.
2. The current state of the industry At first glance, the industry of optical passive devices seems to develop faster than optical active devices, but behind this glory, there are still some problems. Ceramic blanks such as fiber optic connectors also need to be imported, and the proprietary intellectual property rights of fiber optic connector technology are almost zero. At the turn of the century, with the development of fiber access networks, dense wavelength division multiplexing systems, and all-optical communication networks, existing optical passive devices that can be mass-produced cannot fully meet the needs. For example, a high fiber density patch panel requires a miniaturized optical fiber connector. A fused taper device cannot produce an intensive wavelength division multiplexer, and a conventional optical switch cannot be used to connect a large number of port matrix optical switches. These problems force people to stay in the production and competition of low-end products, and must develop high-end optical passive devices to meet the needs of the development of optical fiber communications.
In response to these problems, some units have worked hard and there are already some achievements. Such as the introduction of a small optical connector assembly fixture, the use of micro-optical device structure can be reused several ways and more than a dozen roads dense DWDM. However, in order to solve the matrix optical switch problem of several tens of wavelength division multiplexing and large port numbers, only photonic integrated devices can be used. From the perspective of the production conditions of existing optical passive device production units, there is a large gap between this and foreign countries.
3. Market Overview At present, the largest market for optical passive devices in China is the single-fiber connector. With the continuous expansion of optical communication applications, especially the gradual optical fiberization of local communication networks, the total demand for optical fiber connectors in China has been continuously expanding in recent years. The average compound annual growth rate in previous years was above 30%. According to the investigation of some manufacturers, the production and sales of optical connectors in China from 1998 to 2000 are shown in Table 2. As can be seen from the table, in 1999 due to the decomposed restructuring of China Telecom, production and sales have decreased. However, in 2000, the sales volume of optical connectors of these manufacturers was 2.339 million sets (including about 1.155 million sets of exports and 1.184 million sets of domestic sales), and the total sales volume was 260 million yuan, an increase of 143% over 1999.
According to the statistical laws of foreign markets, the market for optical fiber couplers is about 1/4 of the market for optical connectors, and the market for two-wavelength multiplexers is roughly the same as for optical couplers. With respect to dense wavelength division multiplexers, it is estimated that the annual demand in China in recent years is several thousand sets. At present, the market for optical switches is small, and the annual demand is about several hundred sets. However, with the development of all-optical communications networks, the demand for matrix optical development for large port numbers will increase.
The development of China's optical devices can be seen from the above, we can see that the development of China's optical devices is not too late, with many achievements; but now the lack of investment, many problems. The author made several suggestions on how to speed up the development of China's optical devices for the reference of relevant parties.
1. Changing investment methods and increasing investment intensity Due to institutional reasons, research funding for universities, research institutes, and enterprises in China is derived from scientific research funding at all levels of the system. In view of the fact that scientific research funding is inherently inadequate, the competent authority often “sprinkles†in the name of “funding†to take care of relevant units. Although the same project of each unit can obtain some funding from different sources, it has to use part of the funds to increase the treatment of scientific researchers in order to stabilize the people. The remaining small amount of money can only be used to collect information, make several samples, write several papers, and “consider†the acceptance requirements of each “contractâ€. In the long run, it is difficult to go deep into scientific research and it is difficult to overcome key technologies, let alone mass production and industrialization.
It is proposed to change the mode of investment and the funds are relatively concentrated, and we cannot engage in “flowering everywhereâ€. All units need to behave in ways that can increase the investment intensity of the project, facilitate innovation, and deepen scientific research.
2. The intervention of large-scale enterprises and the enhancement of the driving force for development must grasp the core technologies of optical devices and develop high-end products, which require large amounts of funds. According to foreign experience, the ratio of capital investment for scientific research, small-batch production, and mass production is 1:10:100. Judging from the current operating conditions of existing optical device companies, it is extremely difficult to rely on their own accumulation to develop. This is because the competition of low-end products is fierce and sales profits have dropped to a very low level; Small, it is very difficult to accumulate funds. The industrialization of capital investment (including venture capital) should be mainly responsible for the company, which makes existing optical device companies unable to carry out the industrialization of high-end products.
Optical active device 1. Development Overview Optical active devices are key components in the optical communication system that convert electrical signals into optical signals or convert optical signals into electrical signals, and are the heart of optical transmission systems. Devices that convert electrical signals into optical signals are called light sources, mainly semiconductor light emitting diodes (LEDs) and laser diodes (LDs). Devices that convert optical signals into electrical signals are called photodetectors, mainly photodiodes (PINs) and avalanche photodiodes (APDs). In recent years, optical fiber amplifiers have become a rookie of optical active devices. Currently, a large number of applications are erbium-doped fiber amplifiers (EDFAs). Raman optical amplifiers are being researched and are very promising.
The study of optical active devices in China began in the 1970s. At that time, western countries imposed high-tech blockades and embargoes against China in accordance with the so-called "Patriot rule," and light active devices were also included. So the Institute of Semiconductors, the Wuhan Institute of Posts and Telecommunications, the 44th Department of the Electronic Department, the 13th Department of the Electronic Department and other units carried forward the spirit of “self-reliance†and developed a so-called short-wavelength optical device with a wavelength of 850nm. For example, GaAlAs/GaAs materials were used. LD and LED light sources, Si-PIN detectors, etc., in the form of a kink or heterojunction. Although the performance of these devices is now poor, it also satisfies the needs of China's initial stage of optical communications.
Since then, these units have developed so-called long-wavelength devices with wavelengths of 1310 nm and 1550 nm, such as semiconductor lasers using buried InGaAsP/In buried dual-structures, PIN detectors using InGaAs/In materials, and the like. The performance of these chips has been greatly improved, but in the initial stage of development, epoxy bonding between the chip and the optical fiber is used. Therefore, the device has poor airtight properties, low bonding strength, and easy displacement of the optical fiber, and thus the entire device. The performance and reliability are poor. Later, a fully metallized coupling packaging process was adopted, which greatly improved the reliability and lifetime of the device, which met the growing needs of optical communications at that time.
Before 1993, China’s optically active components required for optical communications were basically provided by domestic manufacturers. As a result, Western countries recognized the need to use “Batumi†for technical blockade and bans in China in active devices and other areas. However, losing the big market in China was not worth the candle. Therefore, it was only necessary to announce the dissolution of "Batum" and foreign optical active devices began to flood into the Chinese market.
2. Industry Status With the rapid development of optical communication technology, the technical requirements for optical active devices have become higher and higher. Although the relevant units in China have made great efforts to track the world trend and achieved breakthroughs in quantum well semiconductor materials and device technology, the level of laboratories for advanced devices such as distributed feedback (DFB) semiconductor lasers have also greatly improved, but due to the input of human resources. The material resources are far from sufficient, and the gap with the advanced level in foreign countries is becoming increasingly prominent.
3. Market Overview According to the investigation of some manufacturers, the production and sales of China's optical active devices from 1998 to 2000 are shown in Table 1. As can be seen from the table, in 2000, the sales of optical active components of these manufacturers were 649,000 (of which about 193,000 were exported and 456 thousand were domestic sales), and the total sales amount was 470 million yuan, an increase of 94.2% over 1999. .
Regarding the market situation of the national optical active devices in 2001, there are different estimates. Some think that it is 1.1 billion yuan, of which the market share of the optical transceiver (light source-detection) integrated module is 40%, the DWDM laser is 39%, the pump laser is 20%, and the optical amplifier is 1%. Some think that it is 1.4 billion yuan, of which the market share of optical transceiver modules is 36%, 36% for DWDM lasers, 14% for pump lasers, and 14% for optical amplifiers. It is expected that light active devices will grow at a rate of 40-50% over the next few years, of which market sales in 2002 will increase by more than 70% from 2001.
It is estimated that domestically produced optically active devices only account for 30-40% of the domestic market.
Optical passive device 1. Development Overview Optical passive devices are devices in the optical communication system that need to consume certain energy and have certain functions without optical-electrical or electrical-optical conversion, including optical fiber connectors, fiber couplers, wavelength division multiplexers, and optical switches. Optical attenuators and optical isolators are the joints of optical transmission systems. Optical connectors are the most widely used and most widely used devices in optical passive devices, followed by couplers and wavelength division multiplexers, and other devices use less. With the development of optical communication technologies, the demand for dense optical wavelength division multiplexers and large port number matrix optical switches will gradually increase.
Research on optical passive devices in China began in the late 1970s with the advent of fiber optic technology. At that time, the connection of optical fibers was one of the six major issues that must be resolved in optical fiber communications. In addition, problems such as shunting, switching, and wavelength multiplexing must be resolved. So, the 23rd Department of Electronics, Wuhan Institute of Posts and Telecommunications, and the 34th Institute of Electronics, and other units “started from scratchâ€, dedicated to the study of all-fiber structures and discrete component combinations (micro-optical devices), developed optical fiber medium-sized Multi-mode optical fiber connectors, splice type and fusion taper type optocouplers and mechanical optical switches meet the needs of short- and long-wavelength multimode fiber communication studies at the time.
Since then, optical communications have entered the single-mode long-wavelength phase and started to be used in large numbers. As optical passive devices are not only more technically demanding, they are also increasing in number and are urgently required for industrialization. In the optical connector, APT optical fiber connector (1.78mm diameter) connector production line was first introduced to meet the needs of the initial development of single-mode optical communication in China. Afterwards, with the success of mass production technology of ceramic casing, the quality of the optical connector has been further improved, and it is easy to assemble. Therefore, there are many companies that have assembled connectors for parts production. In the area of ​​fiber couplers, the introduction of microcomputer-controlled fusion taper devices has made coupler production simpler; more gratifyingly, through theoretical research and practical exploration, various broadband products can be produced on the same equipment. Couplers and two-wavelength wavelength division multiplexers have excellent product performance, thus forming an optocoupler industry. Most of the optical connectors and optocouplers used in current optical communication systems in China are domestically produced.
2. The current state of the industry At first glance, the industry of optical passive devices seems to develop faster than optical active devices, but behind this glory, there are still some problems. Ceramic blanks such as fiber optic connectors also need to be imported, and the proprietary intellectual property rights of fiber optic connector technology are almost zero. At the turn of the century, with the development of fiber access networks, dense wavelength division multiplexing systems, and all-optical communication networks, existing optical passive devices that can be mass-produced cannot fully meet the needs. For example, a high fiber density patch panel requires a miniaturized optical fiber connector. A fused taper device cannot produce an intensive wavelength division multiplexer, and a conventional optical switch cannot be used to connect a large number of port matrix optical switches. These problems force people to stay in the production and competition of low-end products, and must develop high-end optical passive devices to meet the needs of the development of optical fiber communications.
In response to these problems, some units have worked hard and there are already some achievements. Such as the introduction of a small optical connector assembly fixture, the use of micro-optical device structure can be reused several ways and more than a dozen roads dense DWDM. However, in order to solve the matrix optical switch problem of several tens of wavelength division multiplexing and large port numbers, only photonic integrated devices can be used. From the perspective of the production conditions of existing optical passive device production units, there is a large gap between this and foreign countries.
3. Market Overview At present, the largest market for optical passive devices in China is the single-fiber connector. With the continuous expansion of optical communication applications, especially the gradual optical fiberization of local communication networks, the total demand for optical fiber connectors in China has been continuously expanding in recent years. The average compound annual growth rate in previous years was above 30%. According to the investigation of some manufacturers, the production and sales of optical connectors in China from 1998 to 2000 are shown in Table 2. As can be seen from the table, in 1999 due to the decomposed restructuring of China Telecom, production and sales have decreased. However, in 2000, the sales volume of optical connectors of these manufacturers was 2.339 million sets (including about 1.155 million sets of exports and 1.184 million sets of domestic sales), and the total sales volume was 260 million yuan, an increase of 143% over 1999.
According to the statistical laws of foreign markets, the market for optical fiber couplers is about 1/4 of the market for optical connectors, and the market for two-wavelength multiplexers is roughly the same as for optical couplers. With respect to dense wavelength division multiplexers, it is estimated that the annual demand in China in recent years is several thousand sets. At present, the market for optical switches is small, and the annual demand is about several hundred sets. However, with the development of all-optical communications networks, the demand for matrix optical development for large port numbers will increase.
The development of China's optical devices can be seen from the above, we can see that the development of China's optical devices is not too late, with many achievements; but now the lack of investment, many problems. The author made several suggestions on how to speed up the development of China's optical devices for the reference of relevant parties.
1. Changing investment methods and increasing investment intensity Due to institutional reasons, research funding for universities, research institutes, and enterprises in China is derived from scientific research funding at all levels of the system. In view of the fact that scientific research funding is inherently inadequate, the competent authority often “sprinkles†in the name of “funding†to take care of relevant units. Although the same project of each unit can obtain some funding from different sources, it has to use part of the funds to increase the treatment of scientific researchers in order to stabilize the people. The remaining small amount of money can only be used to collect information, make several samples, write several papers, and “consider†the acceptance requirements of each “contractâ€. In the long run, it is difficult to go deep into scientific research and it is difficult to overcome key technologies, let alone mass production and industrialization.
It is proposed to change the mode of investment and the funds are relatively concentrated, and we cannot engage in “flowering everywhereâ€. All units need to behave in ways that can increase the investment intensity of the project, facilitate innovation, and deepen scientific research.
2. The intervention of large-scale enterprises and the enhancement of the driving force for development must grasp the core technologies of optical devices and develop high-end products, which require large amounts of funds. According to foreign experience, the ratio of capital investment for scientific research, small-batch production, and mass production is 1:10:100. Judging from the current operating conditions of existing optical device companies, it is extremely difficult to rely on their own accumulation to develop. This is because the competition of low-end products is fierce and sales profits have dropped to a very low level; Small, it is very difficult to accumulate funds. The industrialization of capital investment (including venture capital) should be mainly responsible for the company, which makes existing optical device companies unable to carry out the industrialization of high-end products.
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