The current-voltage (I-V) characteristics of a laser diode describe the relationship between the current flowing through the device and the voltage applied across it. : 3 Driven by voltage, the doped. When using a laser diode it is essential to know its performance characteristics because they can easily be destroyed if the circuit conditions are not right. Accordingly it is necessary to understand the main laser diode specifications and characteristics and how they can relate to real electronic. This chapter starts with a brief recap of the fundamental aspects and elements of diode lasers, including relevant features of the standard device types, with an emphasis on the advantages of quantum heterostructures for their effective use as active regions in the lasers.