In this paper, we study the spectral properties of angled-grating high-power semiconductor lasers, also known as distributed feedback (DFB) lasers. We have derived a closedform expression to describe the cavity resonance. The results of this model are shown to compare favorably with experimental data. Intrinsic device parameters such as coupling coefficient and grating period are shown to be correlated to spectral and nearfield characteristics. The formulations and insights developed in this paper allow one to calculate these critical design parameters for optimum performance.