What does the term "tunable laser" refer to?

The term "tunable laser" specifically refers to a type of laser that can adjust its output wavelength across a specific range. This tunability allows the laser to emit light at different wavelengths, enabling various applications in science, medicine, and industry where specific wavelengths are required for tasks such as spectroscopy, telecommunications, and laser processing. The ability to change wavelengths makes tunable lasers versatile tools, allowing them to be used for a variety of tasks by optimizing the output to ideally suit the needs of a particular application.

In contrast, the other options describe characteristics of different types of lasers or limitations. A laser that is limited to a single wavelength does not provide the flexibility that defines a tunable laser. Similarly, a laser with fixed output power and one dedicated to continuous operation do not prioritize the adjustable wavelength feature, which is the key characteristic of a tunable laser.