What determines the characteristics of a laser?

• A. Size and Color
• B. Brand and Model
• C. Wavelength and Power
• D. Temperature and Humidity

Answer: (C)

The key factors that define what a laser does are its wavelength and its power. The wavelength, basically the color of the light, is set by the particular lasing transition in the gain medium (whether gas, liquid, or solid). That choice fixes the photon energy and how the laser light interacts with materials, including absorption, scattering, and penetration depth. The power, or the energy per unit time the laser emits, comes from how the device is pumped and how the optical cavity amplifies light, determining how bright the beam is and what applications it can handle, from delicate illumination to cutting or welding.

Size or color of the device doesn’t change the fundamental light that comes out, and brand or model doesn’t alter the beam’s physics either. Temperature and humidity can influence performance stability, but they don’t set the intrinsic wavelength and power of the laser.