Study On Narrow-linewidth DFB Semiconductor Laser Based On Reconstruction-equivalent-chirp Technique

The 21st century is the era of information and photons.With the dramatically growth of the Internet all around the world,communication industry has already long past the era of telecommunication-based network.The optical fiber communication is even taking over the task of transmitting the huge traffic of radio and television network now.With the popularity of smart phones with Android or IOS operating system,mobile payment,sharing bicycles,video chating,viewing news anytime and anywhere has become an important part of most people's daily life,the Internet is not just a leisure tool anymore,it has changed the way people live,becomes a necessity of life.This poses a higher demand for the capacity and transmission speed of the fiber optic communication network,and the requirement for a semiconductor laser as a light source of the communication system is a narrower linewidth.Because a narrower linewidth means higher spectral efficiency and farther effective transmission distance.Specially designed complex grating structure can improve the performance of the laser,including narrowing the linewidth.The problem is that these structures has to be fabricated through the electron-beam lithography technology or the nano-imprinting technology which can cost a lot time and money,so it is not suitable for commercial applications.The lasers we proposed in this paper using the reconstruction-equivalent-chirp(REC)technique proposed by our laboratory to design and fabricate the grating structure.The REC technique can fabricate complex equivalent sampling Bragg grating structures using conventional holographic exposure and ordinary secondary lithography process.The performance of the laser with this kind of grating structure can be optimized to meet the requirement of industrial applications.The main contents of this paper are as follows:In the first chapter of this paper,the application of semiconductor lasers is briefly introduced.At the same time,the basic structure of semiconductor laser,the principle and key part of REC technology and the theoretical knowledge about the linewidth of semiconductor laser and the way of measuring linewidth are introduced.In the second chapter,an equivalent CPM-Apodized narrow-linewidth semiconductor DFB laser based on REC technique is proposed.The simulation results show that the new grating structure can suppress the spatial hole burning effect to narrowing the linewidth.Then,the performance of the finished product of the laser with equivalent CPM-Apodized grating is measured,a narrow linewidth of 224KHz at room temperature is achieved.The third chapter is an experimental exploration of the linewidth narrowing ability of the optical feedback.It is proved that using optical feedback can narrow the linewidth of the DFB laser,and the concrete realization of the feedback structure needs further study.The fourth chapter introduces design and fabricate process of the buried heterostructre structure semiconductor laser based on the REC technology.The static and dynamic performance of the obtained laser are tested well,and the structure of the laser has great development space for further optimization.The fifth chapter is the summary and prospect of this article...