Line of Sight Communication Through Laser I-Physics-Lab Report, Exercises of Physics

Download Line of Sight Communication Through Laser I-Physics-Lab Report and more Exercises Physics in PDF only on Docsity! Line of sight communication through laser Submitted to: Dr. Asloob Ahmad Mudassar Submitted by: Yasir Ali M.Phil. Physics DPAM PIEAS docsity.com Laser is known to be a well directional light source. It has plenty of applications in practical life. Here we are considering a simple application of laser in communication for two places which are in light of sight. Free Space Optics:-. Line of sight communication by laser has some practical applications. Optics which deals with such applications of laser is known as free space optics FSO. Wireless communication through radio frequency (RF) also uses free space but laser communication has some advantages over RF systems. Advantages are i) less mass, power and volume than RF systems ii) intrinsic narrow beam and high gain of laser beam and iii) no restriction in using or selecting frequency. FSO offers a high bandwidth, that is, 2.5 gigabits/second, for communication through air. In USA fiber and copper cable technologies are used for communications between companies but due demand of high bandwidths in some cities small FSO networks are used for communications. In Europe fiber-optic companies are now offering FSO to those companies which are seeking for high speed communications. Commercially FSO provides much greater data transfer rates than digital subscriber lines and coaxial cables. FSO faces some problems. These are mainly due to weather conditions. In bad foggy weather laser light is absorbed by atmosphere, which limits range of FSO. In clear-sky conditions FSO are very reliable. FSO technology started in 1960s. But due to sensitivity to bad weather conditions and also due to the invention of fiber technology, its use is not so commercialized. FSO can provide high speed communication between buildings, between building and fiber optic network or ground and satellite. It can be installed in days or even in hours while optical fiber is installed in months. Due to some limitations of optical fiber technology, interest in FSO is renewed. Principle: -. Light has an interesting property of recording information when it strikes a surface. This property of light we are able to see the world around us. When light strikes a vibrating surface it will record information about the vibration of that surface. If the vibrating surface is producing sound then the same sound is recorded by laser which can carry it to long distance. We can store sound in laser light in another way. As we know sound is converted into electrical signal by microphone. If this signal is made input to a laser typically a diode laser, then the light produced by such a laser has information of sound. Phtodetector on receiving side receive the laser light which converts it into electrical signal and that electrical signal after passing through some electronic device is converted into voice by speaker. Laser communication is safe. Radio frequency (RF) systems propagate radio frequencies in air in all direction which can be received by any receiver tuned on that frequency. In laser communication, light cannot be received by everyone. Normally laser communication is duplex. In this system sender sends data to receiver and receiver send signal as acknowledgement to sender. So if laser beam carrying data is trapped in between receiver and sender, then it is detected quickly by receiver and sender both. Some lasers have frequency in invisible range, which adds to safety of laser communication. docsity.com