| The integrated optics arises from the foundation of the needs of emerging technologies, such as the optical communication, the light computer and the optical information processing. The concept of integrated optics was proposed in 1969 by American Bell Laboratory Dr. Miller. Based on the photoelectronics and microelectronics, the integrated optics is a new science to study and develop optical device and a mix optics-electronics component system used the integration method. The integrated optics combines the optical fiber with the integrated optical circuits, and promotes the optical communication considerable development enormously. The integrated optics usually makes light-emitting elements, lens, optical transmission, light modulator, light coupler and light receiver connect in together utilizing the optical waveguide and integrate on the substrate, accordingly forming the miniature optics system with certain independent function. Waveguide is a basic structure in integrated optical devices and plays an important role in the fabrication of various optical devices because of its excellent characteristics, possibility in integration and rather low cost in manufacturing. So far, many people have investigated many methods to fabricate high-quality optical waveguide. At present, the most popular methods include metal diffusion, ion exchange, film deposition and ion implantation etc. As a mature material surface modified technology, ion implantation technology is an effective method to form optical waveguide. It has many merits including the accurate control of the amount of implanted ions and the thickness of the formed waveguide, weak confinement of the material and its crystal direction, and low requirement of the forming temperature of the waveguides, etc. Up to date, ion implantation technology has been successfully used to form optical waveguide structures in series of optical materials such as optical crystals, glass, semiconductors, etc.Optical waveguide can confine the optical energy in small space and improve the optical energy density, and thus make better use of the nonlinear nature of the nonlinear crystal or reduce the pump threshold of laser material. Optical waveguide used in waveguide lasers, has the important application prospect in the field of optoelectronics, especially in optical communications and the development of the solid-state lasers. Compared with the body of laser, waveguide lasers can reduce the optical power of the excitation source to achieve high efficiency of laser oscillation and amplification, so that the pump threshold of lasers reduces two orders of magnitude. Fabrication of the waveguide in the laser crystal, which is the premise preparation of generating waveguide laser and the foundation of studying waveguide laser, has important practical significance. As present, the ion implantation technology has been applied in much laser crystal material to form a waveguide.The yttrium aluminum garnet crystal, chemistry general formula is Y3Al5O12(YAG) and belongs to the cubic class, with the garnet structure. It is an excellent laser material with excellent optical, physical, chemical properties and mechanical stability, such as high thermal conductivity, high calorescence stability. In virtue of the very high transmittance in the infrared, visible, ultraviolet band, the YAG crystal is an excellent material to serve as the optical window and the substrate and has been widely used in many fields, especially in the high-temperature and high-energy radiation applications. The YAG crystal also has optical isotropy, un-birefrigent effect and good homogeneity of the material, thus becomes the preferred optical materials on many occasions. Neodymium doped yttrium aluminum garnet crystal serves the yttrium aluminum garnet (abbreviated as YAG) single crystal as substrate material, mixed with an appropriate amount of trivalent rare earth ion Nd3+ to replace the original Y3+ ion, which formed a purple Nd3+:YAG crystal.The Nd:YAG crystal with high-gain, low laser threshold, high power, few absorption of the 1064nm light-wave, good thermal conductivity and thermal shock, is suitable in many kinds of workings (continuous, pulsed, Q-switch, mode-locking, etc.). It is commonly used in the near-and far-infrared solid-state laser and second harmonic generation, third harmonic generation applications, and widely applied to scientific research, medical, industrial, military and other fields. Compared with neodymium doped yttrium aluminum garnet (Nd:YAG), the pulse laser efficiency of the neodymium/cerium codoped yttrium aluminum garnet (Nd:Ce:YAG) laser crystal enhance 70%. Nd:Ce:YAG is the most ideal laser material for the high repetition air cooling and miniature laser systems, due to its specific capabilities of low threshold, strong anti-violet radiation resistance, stability in the repetition frequency work situation, stability of the ambient temperature and low cooling requirements.The present work is mainly focused on two aspects, as follows:(1) The study of Nd:YAG waveguides by ion implantation. We report the fabrication of planar waveguide in Nd:YAG by 500 keV H+ implantation at dose of 6×1016ions/cm2. We perform the prism coupling method to measure the dark modes and reconstruct the refractive index profile of the planar waveguide by the reflectivity calculation method (RCM). A typical end-face arrangement is utilized to measure the near-field intensity distribution and the propagation loss. We fabricated planar waveguides in Nd:YAG laser crystal by O3+ ion implantation at an energy of 6MeV. We investigate the guiding properties and luminescence emission features. Optical channel waveguide in Nd:YAG crystal is fabricated by using a stripe photoresist mask. The dark modes, transmission loss, near-field intensity distribution and the annealing performance are researched in detail.(2) To our knowledge for the first time, we fabricate channel waveguides in Nd:Ce:YAG laser crystal by ion implantation. We successfully produce a channel waveguide in Nd:Ce:YAG by using ion implantation of 6MeV carbon ions at dose of 2×1015ions/cm2 The guiding properties and the luminescence emission features are studied. We first report the channel waveguide formation in Nd:Ce:YAG crystal by the implantation of oxygen ions at an energy of 6MeV and a dose of 1×1015ions/cm2. We carry out the m-line method to measure the dark-mode spectroscopy of the planar waveguide and reconstruct the refractive index profile by the RCM. We measure the near-field intensity distribution and the propagation loss by the end-face coupling arrangement. |
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