Following a brief overview of semiconductor device operating principles, this tutorial focuses on diode lasers and their use in fiber optic and wireless optical communication lasers. Fixed wavelength, single-mode diode lasers (including DFB, DBR, and external grating coupled devices) and tunable diode lasers (including three-section DBR lasers, coupled Y-cavity lasers, sampled grating DBR lasers, vertically-integrated devices, and movable mirror vertical cavity lasers) will be emphasized. The primary thrust of this tutorial will be to provide the participants with a basic, intuitive understanding of these important devices. Problems related to device manufacturing will also be discussed.