Controllable Growth Of Tetragonal Phase KDP Single-Crystalline Fiber

Single-crystalline fiber has the physical properties of bulk single crystal and the characteristics of photoconductive glass fiber.Due to its high specific surface area and light-confinement effect,single-crystalline fiber exhibits good heat dissipation capability and high laser power output.Single-crystalline fiber is a new type of optical material with excellent performance.It has broad application prospects in fiber lasers,frequency conversion,infrared laser conduction,and high temperature detection.Recently,our research group discovered that KDP can grow one-dimensional micro-nano tetragonal single-crystalline fibers in an aqueous solution at room temperature.The growth mechanism of this tetragonal phase KDP single-crystalline fiber is different from the growth mechanism of the tetragonal phase KDP bulk crystal.KDP single-crystalline fiber only grows along the c axis,and it' s a and b axis directions do not grow,while the KDP bulk crystal is three-dimensional growth.The study of the growth mechanism of these two different forms of crystals has important theoretical significance.Not only that,high-efficiency second harmonic generation has also been observed in the tetragonal phase KDP single crystal fiber,which indicates that in addition to the traditional bulk KDP/DKDP crystals,low-dimensional KDP crystals are also promising-nonlinear optical materials.And it will play their role in the application of flexible and miniaturized equipment in the fields of optical communications and high-energy lasers.More importantly,in the course of this experimental research,the research group developed a low-cost,simple,high-efficiency and suitable for water-soluble crystal single-crystalline fiber growth method.There are much work to do in order to comprehense the factors affecting the growth of tetragonal KDP single crystal fibers.The research content of this paper can be divided into five chapters:The first chapter is a literature review.In the second chapter,a tetragonal phase KDP single-crystalline fiber is grown by the solution self-assembly method and it is preliminarily judged that the growth of the single-crystalline fiber is related to the supersaturation of the solution.In Chapter 3,the solubility curves of KDP four-square and tetragonal KDP single crystalline fibers are measured by weighing method and hanging crystal method respectively.In Chapter 4,the next growth of tetragonal phase KDP single-crystalline fiber was carried out by building crystal growth equipment by oneself,and the factors affecting the growth of single-crystalline fiber were discussed.Chapter 5 is the main content of the second part.In this chapter,two single-crystalline fibers with different crystal phases and different morphologies of DKDP crystals are obtained by the solution self-assembly method,and the growth of the two crystal phase in the solution is observed.The single-crystalline fiber structures of these two DKDP crystals were confirmed,and optical experiments were carried out.The innovations of this paper are as follows:1.For the first time,an one-dimensionally grown tetragonal phase KDP single-crystalline fiber was obtained in a solution with high supersaturation at room temperature,which realized the controllable growth of KDP single-crystalline fiber.And we provided a new growth method for the growth of single-crystalline fiber of water-soluble crystals.2.It is the first time to reveal the difference between the solubilities of one-dimensional tetragonal phase KDP single-crystalline fiber and large bulk KDP crystal.3.For the first time,two single-crystalline fibers with different crystal phases of DKDP were obtained by solution self-assembly method at room temperature,and the phase transition property of the two crystal phases was observed under the microscope.One crystal phase is monoclinic,the space group is P21/c,the unit cell parameters are a=14.599(5)(?),b=4.503(5)(?),c=18.651(5)(?),?=108.041°,It is a new crystal phase of DKDP crystal,and the other is tetragonal crystal phase.The tetragonal KDP single-crystalline fiber has excellent nonlinear optical properties.