| Laser Diode(LD) has the advantages of high electro-optic conversion efficiency, small volume, light weight, direct modulability and the prominent characteristics of high performance, reliability, longevity of service etc. In the past few years, LD has been applied in almost all the fields of optical electronics and has become the core device of optical electronics technology. However, the inherent construction features of LD decide that a serious deficiency exists, that is, the asymmetry of beam. And the beam divergence angle is very big. In most practical applications, in order to obtain good beam quality, it is necessary to output the LD coupling optical fiber. Therefore, developing the laser diode module which packages the LD and optical fiber with low cost and high efficiency is becoming a very meaningful research project.In recent years, the development of LD module with optical fiber output has been drawing attention at home and abroad. The high power module with high technology is mostly related to some key technologies, such as optical fiber technology, micro-optical technology, and precise processing technology, coupling package and precision machinery and so on. When high power LD is coupled to multi-mode optical fibers, the obtaining of optimal coupling efficiency should take into account their characteristic parameters'matching, that is, the matching of radiate area, divergence angle and output power when the core diameter and numerical aperture of multi-mode fiber are coupled to LD. And something else should be taken into consideration, such as end surface treatment and how to embed lens into coupling system. In many cases, the processes should be simplified and the costs should be reduced in order to obtain optimal performance/price ratio.At present, there are three main package forms between LD and optical fiber, coaxial type package, double in-line package, butterfly package. On the basis of studying all kinds of coupling systems and their application conditions, a new type of coupling system composed of cylinder lens and hemispherical micro-lens is designed, and a new type of LD module with optical fiber output is developed. This module has simple configuration, high coupling efficiency, low cost, not strict with the requirement of coaxiality in metal processing, and it can be adjusted conveniently and precisely to realize five-dimension adjustment between LD and optical fiber.1. The basis structure and the characteristic of optical field of LD as well as the principle of fiber transmission are analyzed. The methods of shaping of semiconductor laser beam and improvement of optical fibers'numerical aperture are illustrated. The theory of coupling between LD and optical fiber is analyzed separately by applying mode field theory and optic coupling theory.2. The actuality of packaging module between LD and optical fiber at home and abroad is generalized. The coupling mode and coupling system between semiconductor laser and fiber are summarized. Both micro-lens fiber coupling system and separate-lens fiber coupling system are analyzed. The structure and coupling characteristics of micro-lens optical fiber's end surface commonly used in micro-lens optical fiber coupling system are emphatically analyzed.3. An indirect coupling system composed of cylinder lens and hemispherical micro-lens is designed. The collimation theory of cylinder lens for semiconductor laser beam and improvement theory of hemispherical micro-lens for numerical aperture are analyzed. Besides, the fabrication of fiber cylinder lens and hemispherical end surface output fiber is introduced in detail.4. A new LD module with optical fiber output is developed and its components are illustrated in detail. Through experiment and testing for power property of the module, it comes to the conclusion that the processing technology of every part of the new developed LD module with optical fiber output is mature so as to decrease the debugging and packaging problems. Therefore, it is helpful for manufacture and application. |
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