Study On The Thermal Characteristic Of High Power Diode Laser Arrays

With the advancement of science and technology, optoelectronic technology has been closely linked with the people's production and livings. Semiconductor laser technology, which is an integral part of optoelectronic technology, also plays an important role. Nowadays, semiconductor laser technology has become the comprehensive, high and new technology with the more rapid development, the more results, and the wider discipline permeability in the twentieth century. It has been widely used in optical fiber communication, industrial materials processing, laser medicine, military and many other fields. In this paper, the structure design, the manufacture, the thermal characteristics and the packaging-induced strain of 800nm high power diode laser arrays were studied, taking account for the thermal characteristics, and some innovative achievements are listed as below:The first one:the paper showed systematically the basic principles and the fundamental aspects of diode laser operation, including optical gain, quantum well structures, lateral confinement, optical waveguides and resonators.The second one: we designed an 800nm semiconductor laser array structure. In order to reduce the threshold current, the thermal resistance and the series resistance, we used strained GaAs_0.86P_0.14 single quantum well, Al_0.35Ga_0.65As material and Al_0.7Ga_0.3As material as the active region, the waveguide layer and the cladding layers, respectively. By manufacturing large optical cavity, the energy being transported in the cladding layers was very small, which leaded to small thermal and series resistances. The cladding layers could be highly doped to reduce the thermal and series resistances. To improve the output power of the diode laser arrays, the fill factor was 50% and the cavity length was 1mm. In order to suppress the appearance of so-called spurious modes, we etched deep grooves and deposited SiO2 in the grooves. These could have a sufficiently high absorption.The third one: 800nm diode laser arrays were provided after optimizing on the etching technique and metallization The peak power can reach to 100.9W at 106.5A at the duty cycle of 20%.The fourth one: the theoretical principle was that the threshold current and slope efficiency could be expressed as an approximately empirical and linear function of temperature. However, the temperature variation of the slope efficiency was an empirical expression indeed. After the optimization of the threshold current method, a method for the temperature of the active region, which was called power-threshold current, was provided, and the deviation was decreased to 4K.The fifth one: Double-side cooling was induced in the CS packaging diode laser arrays. The optimized CS packaging diode laser arrays dissipated the waste heat more efficiently. The thermal resistance of the optimized diode laser arrays was 0.1588K/W and reduced 0.03K/W compared to the traditional CS packaging diode lasers.The last one: The strain caused by device packaging was studied in high power semiconductor laser arrays. In the theory and experiment, we demonstrated that the electroluminescence microscopy could show the qualitative information for the packaging-induced strain and defects on the solder layers. After soldering, Due to the different thermal expansion coefficients of laser bar and Cu heat sink, the packaging-induced strain was induced to the active region inevitably. Furthermore, in experiments, we showed that the maximum strain level could be reduced by increasing the solder interface thickness.