The Characteristic Research Of Optical Transmission On Spatial Light To Multimode Fiber Coupling System

Information transmission among the satellites and satellite-ground has beenachieved. It utilized wireless transmission to broadcast signals which was loaded in laser.After developing many years, submarine cable and fibers have been set up to implementrapid information transmission throughout the world. If space light was coupled intofiber, all-optical networks will be realized. It can take advantage of all-optical networksto transform information for the inconvenience of setting up fiber.This paper constructs a space light-fiber coupling system that achievestransmission from space light to fiber. The mainly context contains:1. It introduces the basic theory and method of the optical system design,reviewing constant several aberration and analyze method of beam quality, which utilizeoptical software ZE-MAX to design Cassegrain antenna and self-focusing lens to fulfillour design necessarity.2. It introduces different composition of space light-fiber coupling system.Through weighing the cons and pros of variety of lasers, this paper chooses thesemiconductor laser. With analysis cons and pros of several optical antenna, this paperchooses Cassegrain antenna. With the influence of coupling efficiency by coupling lens,it chooses self-focusing lens. According to difference between single mode fiber andmultimode fiber, the coupling efficiency of multimode fiber would be higher. Therefore,it chooses multimode fiber.3. Through the analysis of Gaussian beam, the higher level Gaussian beam cangenerate hollow beam, which enlighten us to utilize plastic system to generate hollowbeam. By discussing the relationship between block radius and the parameter ofCassegrain antenna, the block radius is the radius of what we generate the hollow beam.It also computes the relationship between the block efficiency and Cassegrain antenna.As what we discussed above, it can basically eliminate the loss of transmissionefficiency inducing by the block of secondary lens and improve the transmissionefficiency of Cassegrain antenna.4. The collimation plays an important role in the optical system. The off-axis would influence the efficiency of optical system. Cassegrain optical system and fibercoupling system are two important sub systems in the space light-fiber coupling system.Their off-axis can influence the coupling efficiency of whole system. This paperanalyzes the transmission efficiency of Cassegrain system under the collimation andoff-axis as well as the coupling efficiency between outgoing beam and multimode fibercoupling system. Hence, it should keep the collimation in the whole system.5. By using the existence laboratory apparatus, this paper design experimentscheme to realize the transmission from the space light to the coupling fiber. Thispaper tests the transmission efficiency of Cassegrain system under the collimation andoff-axis as well as the coupling efficiency between outgoing beam and multimode fibercoupling system. In the meanwhile, it can be analyzed with the image and data underthe collimation and off-axis. Finally, it use beam quality analyzer to analyze the beamquality from multimode outgoing fiber and be proved as Gaussian beam.