The Goos-H(?)nchen Effect Of The Transmitted Light Beam And Its Mechanism

The fundamental topic of the GH (Goos-H?nchen) effect has attracted increasing interest recent years because of two important aspects. On the one hand, the GH effect can be analogous to the tunneling delay in research of superluminal phenomenon which is the controversial issue of the frontiers; on the other hand, the GH effect is claimed to be applicable to optical microstructure such as optical sensors, optical switches, and integrated optics devices. However, the conventional concept of the GH effect simply refers to the small lateral displacement of the totally reflected beam at a dielectric interface from the position predicted by geometrical reflection, and is considered closely related to the evanescent field in the optical less dense medium. Our recent work has demonstrated that the GH displacement will also take place when a beam transmits through a thin dielectric slab. This GH displacement can be negative as well as positive and has no concern with the evanescent field. The aim of this Ph. D. dissertation is to investigate the properties and mechanism of the transmission GH displacement and to perform experimental measurements of the displacement. The main contents involved in this dissertation are as follows:The first chapter is the introduction. Firstly, the history and current researches on GH effect are briefly reviewed. Secondly, the main two approaches employed to discuss the GH displacement theoretically are introduced as the stationary phase approach and the energy-flux approach, respectively. We illustrate the experimental measurements about the GH displacement and its applications. Lastly, the primary contents discussed in this dissertation are stressed.In the second chapter, we first investigate the GH displacement of a light beam transmitting through a thin dielectric slab in vacuum by the first-order approximation of the transmission coefficient, i.e., the stationary phase approach. It is shown that the GH displacement can be resonantly enhanced. Necessary conditions for the displacement to be backward are advanced by considering the restrictions on the incidence angle and the slab thickness. Secondly, with the help of the second-order approximation of the transmission coefficient, we find that the actual transmitted light beam undergoes four non-geometrical effects, including GH displacement, angular deflection, width modification and longitudinal focal shift when compared with the results predicted by geometrical optics. The GH displacement and the angular deflection are shown to be dependent on the width of the beam waist. Thirdly, numerical simulations of the GH displacement for a Gaussian-shaped light beam transmitting through the dielectric slab are performed. The numerical results agree well with the theoretical ones. Lastly, we made experiments to observe the backward (negative) GH displacement of the microwave beam transmitting through thin slabs. The experimental results are in good agreement with the theoretical ones.In the third chapter, firstly, we give a physical explanation for the mechanism of the GH displacement of a light beam transmitting through a thin dielectric slab configuration. From the view of the multiple reflections inside the slab, we find that the actual transmitted beam with the GH displacement originates from the coherent interference between the successive transmitted constituents that arise from the multiple reflections inside the slab. We conclude that the GH displacement of the transmitted beam is produced by the mechanism of reshaping, rather than the distortion of the transmitted beam. Secondly, the physical restriction on the incidence angle and thickness of the slab for the transmitted beam maintaining well the shape of the incident beam is advanced mathematically. Lastly, numerical analysis of the reshaping of the transmitted beam has been given by Gaussian-shaped incident beam. It is shown that we can obtain the reshaping actual transmitted beam with negative displacement when the restriction conditions are satisfied; otherwise, it is meaningless to discuss the displacement of the transmitted beam due to the serve distortion of the beam profile. The problems investigated in this chapter form the theoretical basis of the discussion on the beam transmitting through optical microstructures.In the fourth chapter, at first, we work out the transmission coefficient of a light beam transmitting through the periodic multiple layer structure by transfer matrix approach, and consequently we investigate the transmittivity and the GH displacement of the transmitted beam by stationary phase approach. As an example, we give a detail analysis on an 11 layer structure with the refractive index in the form of ( n1 n2)5n1. We find that the GH displacement of the transmitted beam is dependent on the effective thickness of the periodic configuration, the refractive index of the medium and the incidence angle of the light beam. It is shown that the displacement can be negative as well as positive in the periodic configuration made up of general materials. The magnitude of the displacement can be of one or two orders of wavelength at transmission resonance. Under specific conditions, such periodic multiple layer structure permits omnidirectional total transmission for incident light with all kinds of polarization states. At last, the numerical simulations for Gaussian-shaped beam are made to demonstrate the validity of the stationary phase approach. The contents discussed here can be identified as the generalization of the discussion from the single layer structure to multiple layer structure.In the last chapter, I summarize the main contents and achievements in the dissertation with brief discussions on further research direction.