How do lasers work in optoelectronics?

Lasers work by producing coherent light through stimulated emission of photons in a gain medium.

In optoelectronics, lasers are used as a source of light for various applications such as communication, sensing, and imaging. The laser consists of a gain medium, which is usually a solid-state crystal or a gas, and two mirrors placed at either end of the gain medium. One mirror is partially transparent, allowing some of the light to escape and become the laser output.

When energy is supplied to the gain medium, it causes the atoms or molecules to become excited and move to a higher energy state. When they return to their ground state, they emit photons of light. In a laser, this process is stimulated by the photons already present in the gain medium, causing a chain reaction of photon emission.

The mirrors at either end of the gain medium reflect the photons back and forth, amplifying the light and causing it to become coherent. The coherence of the light means that all the photons are in phase with each other, resulting in a narrow beam of light with a well-defined wavelength.

The wavelength of the laser output depends on the properties of the gain medium and the mirrors. By adjusting these properties, lasers can be designed to emit light at specific wavelengths, making them useful for a range of applications in optoelectronics.