Designs And Implements Of One-way Optical Transmission Systems

In recent years, many scientists proposed the concept of "all-optical network", optical signal carrying information is used in the whole network to realize the high-speed transmission and exchange of information, the data information from the beginning to the end of the entire transmission process always use the optical signal, there is no photoelectric device in the whole process, thus replacing the traditional electrical information. Compared with traditional integrated circuit system, the integrated optical system has a higher degree of integration, greater bandwidth, lower loss, minimal signal delay. Therefore, the integrated optical system has attracted more and more attention. In order to realize the integrated optical system, all-optical devices become research focuses. As we know, the electric diode is the fundamental element of the electric circuit. Similarly, the optical diode is also the fundamental element of the integrated optical system. In order to realize optical diode, many unidirectional optical transmission systems and asymmetric optical transmission systems have been proposed and studied. In the first part of this dissertation, we have designed and fabricated a grating-photonic crystal composited structure, by using the diffraction grating to change the direction of the incident light, the direction of the incident wave vector is selected by the directional band gap of photonic crystal, and the unidirectional optical transmission is obtained. In the second part of this dissertation, we have designed a kind of metal-dielectric composited structure, by using the coupling condition of the excited SPP is different in different media, a unidirectional optical transmission is obtained. Based on the analysis of a variety of composite structures, the physical mechanism of the unidirectional optical transmission is verified. The main work included in this dissertation are:1. One-way optical transmission in silicon grating-photonic crystal structureWe design a grating-photonic crystal composite structure. The unidirectional optical transmission is obtained at the wavelength of 1355 nm to 1470nm?For the plane wave incident from positive, the incident light can pass through the grating-photonic crystal composite structure, transmittance can reach 95% at the wavelength of 1360 nm. On the contrary, for the plane wave from negative, the incident light is blocked, and the transmittance is zero.2. Theory analysis and experimentation of the One-way optical transmission in silicon grating-photonic crystal structureBased on the photonic crystal band structure calculation, there exists a directional bandgap between 0.4086a/? and 0.4428a/?. Such a gap stops the propagation of light along the ? - X direction but allows the propagation of light along the ? - M direction, the unidirectional optical is obtained in the end. In the experiment, the sample is produced by electron etching technology, the unidirectional optical transmission is verified at the range of 1355nm to1375 nm.3. Unidirectional optical transmission in the sliver-silicon T-shaped composite structureIn this paper, we design a metal-dielectric composite structure which is composed of Ag nanoparticle arrays and Si nanoparticle arrays. The one-way optical transmission is obtained at the range of 1455 nm to 1520 nm. For the plane wave incident from positive, the incident light can pass through metal-dielectric composite structure; For the plane wave from negative, the light cannot pass through composite structure.4. Asymmetric optical transmission of multiple composite structuresBy analyzing the electric-field distribution of T-shaped composite structure unit and a row of T-shaped composite structure, we explained the cause of unidirectional optical transmission. For the positive direction, the excited SPP can be coupled to the dielectric nanoparticles to transmission; On the contrary, the excited SPP will exponential decay in the air when the light is incident from negative direction. Furthermore, by analyzing the separate T-shaped composite structure and H-shaped composite structure, the physical mechanism of unidirectional optical transmission is verified. The metal-dielectric composite structure provides a new and simple way for the design of optical diode-like integrated device.