| Tapered lasers have become one of the current research hotspots because of their special structures of tapered optical amplification region and ridge optical injection region,enabling them to have both high output power and beam quality.At present,the research on the traditional strip semiconductor laser is relatively mature.In contrast,most of the research on the tapered laser is to improve its beam quality and power.However,there is less research on its reliability and less research on the failure mechanism.How to improve the reliability of the tapered laser is an urgent problem to be solved.Therefore,the work of this paper mainly focuses on the key scientific problem of failure cause and mode of tapered laser.According to the basic principle,chip structure,manufacturing technology and existing failure analysis methods of tapered laser,the failure analysis research scheme of976 nm tapered laser is designed in this paper.The simulation model is established according to the thermal theory and the photon and carrier transport diffusion model,and the simulation research on the thermal distribution and light field distribution in the active region of the device is carried out.The failure mechanism of tapered laser is studied in detail by using SEM,3D X-ray and other characterization techniques.The main research is as follows:The multi-physics simulation software COMSOL Multiphysics was used to simulate the tapered laser,and then the thermal stress distributions in the ridge and tapered regions were obtained.A porous heat sink was designed,and the heat dissipation capacity of the improved heat sink and the ordinary heat sink was compared through the simulation result.The optical simulation analysis of the 976 nm tapered laser was carried out;the distribution of carriers and optical field was simulated,and the influence of current on the distribution of optical field and beam quality was obtained.The optical,electrical and thermal characteristics of the tapered laser are tested,and the current,thermal resistance and thermal distribution of the failed sample are obtained.Through failure characterization and analysis of the samples,it is clear that the interface between tapered region and Ridge region is the key region prone to failure,which is consistent with the simulation results.At the same time,the failure modes such as spatial hole burning effect,cavity surface optical catastrophe,cavity surface dirt and damage,poor welding and so on in tapered laser are analyzed in detail.Using low light level microscope to locate the defects of tapered laser,there are obvious defects in waveguide,chip edge and DBR region.The common failure mechanism is verified by the combination of simulation and experiment,and the failure mechanism of tapered laser is clarified,which provides theoretical support for the process improvement and reliability improvement of 976 nm tapered laser. |
