Wavelength Width Dependence of Cavity Temperature Distribution in Semiconductor Diode Laser

The study of heat distribution in laser diode shows that there is nonuniform temperature distribution in cavity length of laser diode. In this paper, we investigate the temperature difference in laser diode cavity length and its effect on laser bar output wavelength width that mounted on usual CS model. In this survey at the first, laser was simulated then the simulations result was compared with experimental test result. The result shows that for each emitter there is difference, about 2.5 degree between the beginning and end of cavity. 1. Introduction High-power infrared diode laser arrays are effective sources for pumping solid-state lasers [1–3]. These laser arrays are composed of one or more laser bars; each laser bar consists of numerous individual laser emitters formed on a single piece of semiconductor [4, 5]. Various characteristics like quantum efficiency, output power, and their dependence on cavity length and composition have been discussed. There are a number of factors that limit the output power and reliability of diode lasers, for example, catastrophic optical damage and overheating. Cavity length increase was used for increasing output power [4]. In this paper at first four laser diode heat sources were considered and this distribution in the cavity was studied and was simulated. Then the temperature distribution was simulated in the single emitter in the laser diode bar that packaged on the CS mount model and then measured the temperature difference in laser diode points in cavity length. Temperature distribution effect on the wavelength width and the wavelength peak shift and other hand simulation results were compared with experimental results. 2. Laser Diode Structure and Simulation Our simulation is based on GaAs, 20？W, CW modes, 808？μm CS laser diode. The laser diode has 19 emitters with 100？μm width stripe and 20% fill factor that was produced in INLC (Figure 1). The laser operation specification is listed in Table 1. Table 1: Laser operation Characteristics. Figure 1: Schematic of laser bar, bar stripe geometry dimension, and CS model packaging laser diode. The mounting of laser bar on the package and the heat removing direction was shown in Figure 2 and layer structure specification is listed in Table 2 and its arrangement was shown in Figure 3. The bar dimensions, thickness, bar width (cavity length), bar length, are 117, 1000, and 9800？μm, respectively. Table 2: Laser bar structure layers specification. Figure 2: Bar packaging position on CS heat sink and heat removed path from the bar to TEC. Figure 3: Laser bar structure