Fundamental Lateral Mode Characteristics Of The 852nm Ridge Waveguide Semiconductor Laser Diode

Semiconductor laser is a kind of laser with semiconductor material as the optical gain medium,and it is called as laser diode because its core is a p-n junction with optical feedback structure.Stimulated emission recombination is generated by injecting current excitation into the p-n junction,and an optical oscillation is established in the resonant cavity to make device work.The semiconductor laser has an important significance in the practical application,it has the advantages of small volume,low power consumption,long service life,high photoelectric conversion efficiency and band wide coverage to highlight.These advantages can be easily used in many occasions.The main application areas of semiconductor laser includes optical fiber communication,optical disk access,spectral analysis and optical information processing.Moreover,it is especially suitable for military applications such as laser night vision,laser fuze,laser ranging,and laser radar and so on.In the high-tech fields of atomic clock,magnetometer,and gyro sensor by atomic sense and probe,cesium spectrum,which is pumped by high performance 852 nm semiconductor laser that has stable mode,high beam quality and narrow linewidth,can be used as precision measurement,satellite photon inertial navigation,space vehicle positioning and guidance.Therefore,high power,low threshold and stable mode characteristics of high beam quality 852 nm semiconductor laser light source has become the focus of research.However,there are still a series of problems in the application of 852 nm laser.For example,the changes in working conditions(such as: temperature,current,etc.)are likely to lead to a more serious instability of the laser,resulting in changes in output power,lasing wavelength,making entire system closing down.It is found that the lateral mode change is a very important factor for the ridge edge emitting lasers.Meanwhile,the fundamental mode output conditions is harsh because lateral mode is affected by many factors,and the physical origin is complex.The lateral direction restrictions for the carriers and photons are weak,which easily lead to instability.Furthermore,due to competition of light waveguide guidance mechanism and mode characteristic exist at the same time in the ridge waveguide structure,the lateral mode control is more difficult.Therefore this paper study on the lateral mode of ridge waveguide laser,the main research contents and results are as follows:1.Based on the waveguide theory and the equivalent refractive index method,the key factors affecting the lateral mode characteristics of the ridge waveguide edge emitting lasers are investigated theoretically.In this paper,the conditions for the generation of different modes,the control method of the mode competition and the stability of the lateral modes propagating in the cavity are analyzed.The lateral structural parameters which are beneficial to the oscillation of the fundamental modes are derived.The optimal laser's performance are obtained by optimizing the whole structure parameters.2.In the lateral direction of the ridge waveguide laser,two kinds of guiding mechanisms,the gain guiding and the weak refractive index guiding,are combined to affect under certain circumstances.The physical process of two kinds of mechanisms mutual conversion are analyzed and simulated by using COMSOL multiphysics analysis software.The relationship between the limiting conditions of the optical waveguide and the lateral mode stability is analyzed by using FDTD simulation.Furthermore the far-field characteristics of the laser are studied;3.Develop the physical research of laser fabrication technology.On the basis of the traditional semiconductor laser fabrication technology,the narrow ridge 852 nm laser is fabricated by the self-alignment technique.The method not only ensures the reliability and accuracy of the semiconductor process,but also improves the yield of the laser.At the same time,we design a set of suitable process flow and method for ultra-narrow ridge laser,that greatly improves the performance of the laser;4.On the basis of theoretical analysis and process preparation,the test and analysis of semiconductor laser are carried out.The key structural parameters are 1mm in cavity length,5?m in ridge width,and 500 nm in ridge depth.Finally,realize 852 nm single fundamental lateral mode stable output.And the laser threshold current of 50 m A,with cavity surface uncoated case the slope efficiency can achieve 0.7m W/m A in average.