Optical fiber communication is an indispensable communication method in modern life, but not everyone knows enough about optical fiber communication. In order to improve everyone’s understanding of optical fiber communication, this article will introduce optical fiber communication based on two points: 1. Selection of optical fiber communication devices, 2. Development trend of optical fiber communication technology.
1. Selection of optical fiber communication devices
A basic fiber optic communication system is very simple: an LED transmitter converts an electrical signal into an optical signal and couples it into a transmission fiber. The optical signal travels through the fiber to an optical receiver, which restores the received optical signal to its original state. electrical signal output.
Choice of fiber optic cable: Generally, silica glass fiber is used for long-distance communication links due to its low loss and high bandwidth. For example, the Ethernet and FDDI standards specify the use of multimode 62.5/125 μm silica glass fiber. These fine-core fibers require high-precision connectors to reduce coupling losses, and for industrial applications, low-cost cables and connectors. Therefore, 1mm POF (PlymerOpTIcalFibers) and 200μm HCS (HardCladSilica) fibers are the best choices, both of which are multimode fibers with a step index of refraction.
The typical loss value of 1mmPOF is 0.2dB/m at 650nm wavelength, while the typical loss value of 200μm HCS fiber is only 8dB/km at 650mm wavelength and less at 820nm wavelength. The core of HCS fiber is quartz glass, and the cladding is a patented high-strength polymer, which not only increases the strength of the fiber, but also prevents moisture and pollution. The outer sheath is 2.2mm polyvinyl chloride. HCS optical fiber can work in the temperature range of -40℃～+85℃, and the erection temperature range is -20℃-+85℃, which meets the system requirements in terms of performance and price.
Selection of working wavelength: The design of optical fiber communication system must consider the influence of fiber loss and dispersion on the system. Since both loss and dispersion are related to the working wavelength of the system, the selection of working wavelength has become a major problem in system design.
Considering the system’s index requirements and the selected fiber, selecting the 820nm wavelength can make the HCS fiber loss as low as 6dB/km, and at the same time, the chromatic dispersion can be minimized.
Choice of light source: At 820m wavelength, LED is the best light source that can be selected. Compared with semiconductor laser, the driving circuit of LED is simple and the cost is low.
To sum up, 200μm HCS fiber is selected for the optical cable, and the HFBR-0400 series of 820nm wavelength of HP company is selected for the optical transceiver. The HFBR-14X2/HFBR-24X2 in this series can reach a rate of 5MBd within a distance of 1500m, and the operating temperature range is -40°C to +85°C. There are ST, SMA, SC and FC port models to choose from. HFBR-14XZ adopts 820nm wavelength AlGaAs type LED, HFBR-24XZ integrates an IC chip including PIN photodetector, DC amplifier and open collector output Schottky type transistor, its output can be directly connected with popular TTL and CMOS integrated circuits connected.
2. Development Trend of Optical Fiber Communication Technology
1. Wavelength Division Multiplexing System
Ultra-large-capacity, ultra-long-distance transmission technology Wavelength division multiplexing technology has greatly improved the transmission capacity of optical fiber transmission systems, and has broad application prospects in future cross-ocean optical transmission systems. Wavelength division multiplexing systems are developing rapidly. The 6Tbit/WDM system has been widely used, and the all-optical transmission distance is also greatly expanded. Another way to increase transmission capacity is to use optical time division multiplexing (OTDM) technology. Unlike WDM, which increases its transmission capacity by increasing the number of channels transmitted in a single fiber, OTDM technology increases transmission capacity by increasing the rate of a single channel. , the single-channel maximum rate achieved is 640Cbit/s.
2. Optical Soliton Communication
Optical soliton is a special kind of ultra-short optical pulse of ps magnitude. Because it is in the anomalous dispersion region of the fiber, the group velocity dispersion and nonlinear effects are balanced accordingly, so after long-distance transmission through the fiber, the waveform and speed remain unchanged. Optical soliton communication is to use optical soliton as a carrier to realize long-distance and distortion-free communication, and the information transmission can reach thousands of miles under the condition of zero bit error.
3. All-optical network
The future high-speed communication network will be an all-optical network. The all-optical network is the highest stage of the development of optical fiber communication technology, and it is also an ideal stage. The traditional optical network realizes all-opticalization between nodes, but electrical devices are still used at the network nodes, which limits the further improvement of the total capacity of the communication network trunk. Therefore, the true all-optical network has become a very important topic. The all-optical network replaces electrical nodes with optical nodes, and the nodes are also all-optical. Information is always transmitted and exchanged in the form of light. The switch does not process user information by bits, but determines routing based on its wavelength.
The Links: G104V1-T03 CM600DX-24T
