Optical Fiber Technology and various access networks (1)

1. Mainstream Optical Network Technology

1. New Optical Fiber Technology

The optical fiber production technology is now mature and is now in mass production. Today, single-mode optical fiber with zero dispersion wavelength λ 0 = 1.3 μm is widely used, the single-mode optical fiber with a zero-dispersion wavelength of λ 0 = 1.55 μm has been developed and has entered the practical stage. Its attenuation at the wavelength of 1.55 μm is very small, which is about 0.22dB/km, therefore, it is more suitable for long distance and large capacity, and is the preferred transmission medium for long distance backbone networks. To meet different development requirements of trunk lines and local area networks, a new type of optical fiber, such as non-scattered optical fiber, low dispersion slope optical fiber, large effective area optical fiber, and anhydrous peak optical fiber, has been developed. However, in the research of ultra-long wave optical fiber, the transmission distance can reach thousands of kilometers theoretically, which can reach the non-relay transmission distance, but it is still in a theoretical discussion stage.

. Optical Fiber Amplifier

1550nm bait-doped Er) fiber amplifier (EDFA), the bait-doped fiber amplifier is a digital, analog, and coherent optical communication repeater. It can transmit different bit rates and transmit optical signals of several wavelengths at the same time. During the update of the optical fiber network, the system converts analog signals to digital signals and from low bit rate to high bit rate. When the system uses the light wave multiplexing technology for expansion, it does not need to change the lines and equipment of the bait-doped amplifier. Bait-doped amplifiers can be used as front amplifiers of optical receivers, post amplifiers of optical transmitters, and compensation amplifiers of optical source devices.

1. 3. Broadband Access

There are various broadband access solutions for commercial and residential users in different environments. The access system provides three main functions: high-speed transmission, multiplexing/routing, and network extension. Currently, the mainstream technologies of the access system include ADSL technology, which can economically transmit several megabits of information per second on the twisted pair copper line. It supports traditional voice services, it also supports data-Oriented Internet access. After the local ADSL Access multiplexing device multiplexing data traffic, it selects a route to the group network to transmit the voice traffic to the PSTN, ISDN, or other group networks.

Cable modem can provide high-speed data communication in a fiber-optic coaxial hybrid network. It divides the coaxial Cable transmission bandwidth into upstream and downstream channels, thus providing VOC online entertainment, Internet access, and other services, it also provides PSTN services. The Fixed Wireless Access System uses many high-tech technologies in smart antennas and receivers. It is an innovative method of access technology and the most uncertain method of access technology, further exploration is required in future practices. However, the optical access system can provide sufficient bandwidth to support a variety of services that are currently foreseeable. However, there are still technical and economic issues that need further product development and technological innovation, to make it a mainstream technology for network access systems in the 21st century.

1. 4. Silicon Technology

The innovation of optical network technology further requires a complete set of components, including lasers, sensors, and modem, from Z optical fiber to composite semiconductor devices. To meet these broad functional requirements, the silicon technology developed for low-cost electronic devices is advancing into the field of opto-electronics. Currently, the silicon-based optical processing is following two silicon optical laboratory SIOB) and micro-electro-mechanical systems (MEMS.

SIOB technology is on a silicon chip. Passive Devices and lasers and sensors can be integrated on the active-character support frame, which is connected to a variety of components. For small modules, optical integrated circuits manufactured using SIOB technology have sufficient density. SIOB technology has been applied to integrated lasers, Photoelectric Sensors, passive wave splitters, WDM filters, non-Optical Fiber suction spherical lenses, Rotating Mirrors, optical steering elements, and electric product metals.

MEMS is a tiny, robust mechanical component, typically smaller than 1mm in size. MEMS has an amazing array of functions and can be integrated with complex chips. Currently, MEMS technology is still in the research stage. Scientists try to use the silicon chip itself to create elements with removable components for optical communication, this technology has broad development prospects and will make a qualitative leap in optical networks.

The Development and Innovation of optical networks require a complete set of components, from Z fiber to composite semiconductor devices. The silicon technology is advancing into the field of opto-electronics and is continuously innovating in this field, the "Silicon optoelectronic technology" is now an interdisciplinary science that lays the theoretical foundation for the development of silicon optoelectronic technology and has become the driving force for the rapid development of optical networks.

Since the middle of 1980s, silicon substrates and their processing technologies have matured. Because silicon has many physical properties that people desire, such as its stable refractive index and easy to control, on a silicon wafer, passive devices can be integrated with lasers and sensors on the support frame. The optical integration circuit manufactured by SioB technology has sufficient density. A large number of chips can be produced after processing a single chip, multiple features have been integrated into the chip. SioB technology has been widely used in integrated lasers, photoelectric sensors, optical fiber splitters, WDM filters, non-optical fiber cables, spherical lenses, Rotating Mirrors, optical steering elements, and electric product metals.

Since the middle of 1990s, Integrated Optoelectronic technology has been applied to communication networks, such as Dragone routers, an optical integrated circuit that combines and routes wavelength channels in the DWDM System, now it has grown from 8 channels to 72 channels, while the micro-motor system MEMS) is a tiny and robust mechanical component. The micro-motor system can be manufactured by means of extended growth, its pattern formation and etching processing, the Integrated Circuit manufacturing technology has been completed on the substrate. We are confident that the innovative technology in the silicon photoelectric field of micromotor systems in the 21st century will be applied to the next generation optical network in the near future.