Laser is a device to produce

A laser (Light Amplification by Stimulated Emission of Radiation) is a device that produces a highly intense beam of light characterized by coherence, monochromaticity, and directionality [t1][t2]. Unlike conventional light sources like incandescent bulbs, which emit incoherent light across various wavelengths and directions, laser light consists of waves that are exactly in phase with one another [t3][t4]. This phase relationship is known as coherence, meaning the crests and troughs of the light waves move in unison [t4][t7]. While white light is a combination of all visible wavelengths, laser light is typically monochromatic, consisting of a single wavelength [t2][t8]. Although the principles of lasers were adapted from masers (which produce coherent microwave radiation), the laser specifically produces coherent light in the visible, infrared, or ultraviolet spectrums [t5][t7]. Therefore, the primary characteristic of the light produced by a laser is its coherence.

Sources

1. [1] https://www.sciencedirect.com/topics/immunology-and-microbiology/laser
2. [2] https://lasers.llnl.gov/education/nifs-guide-how-lasers-work