Which of the following accurately defines a diode laser?

A diode laser is accurately defined as one that utilizes a semiconductor as its active medium, specifically operating within the Near Infrared spectrum. This semiconductor structure allows for efficient photon generation when an electrical current is applied. The unique characteristics of diode lasers, such as their compact size, efficiency, and ability to be integrated into various devices, are a direct result of their semiconductor composition.

Additionally, diode lasers can operate in continuous wave or pulse modes, making them versatile for different applications. However, the defining characteristic lies in their semiconductor medium and spectral range, which makes option C the most precise and relevant definition of a diode laser. Other definitions that suggest the laser can only be pulsed or operates without an active medium do not capture the essential features of diode lasers.