A laser diode works based on the principle of stimulated emission of photons. It consists of a semiconductor material sandwiched between two layers that create a p-n junction. When a forward bias voltage is applied across the p-n junction, electrons and holes recombine within the semiconductor material. This process releases energy in the form of photons. For laser diodes, this photon emission is stimulated to occur in a coherent and directional manner, leading to the production of laser light. The emitted photons bounce back and forth between the reflective facets of the diode cavity, amplifying through stimulated emission until a coherent laser beam emerges through one of the facets.
The action of a laser diode involves converting electrical energy into light energy through the process of stimulated emission. When electrons and holes recombine in the semiconductor material of the diode under forward bias, they release photons. These photons then stimulate other excited electrons to emit additional photons with the same wavelength and phase. This process creates a cascade effect that amplifies the light emission and leads to the generation of a coherent laser beam with specific characteristics determined by the diode’s design and materials.
A diode is a semiconductor device that allows current to flow in one direction while blocking it in the opposite direction. It consists of a p-n junction where electrons and holes can flow under forward bias (when the anode is positive relative to the cathode) but are blocked under reverse bias. In forward bias, electrons from the n-type material and holes from the p-type material move across the junction, creating a conducting path for electrical current. In reverse bias, the depletion region widens, preventing significant current flow due to the absence of free charge carriers.
A diode-pumped laser (DPL) operates by using laser diodes to pump or excite a gain medium, typically a solid-state crystal or glass doped with rare-earth ions. The laser diodes emit intense light at a wavelength that matches the absorption band of the gain medium. When the gain medium absorbs this light, it becomes excited and produces population inversion—a condition where more atoms are in higher energy states than lower energy states. Stimulated emission then occurs within the gain medium, resulting in the emission of coherent laser light. Diode-pumped lasers are known for their efficiency, compact size, and reliability compared to traditional gas or lamp-pumped lasers.
Laser diodes are indeed considered real lasers. They operate on the same fundamental principle of stimulated emission as other types of lasers, such as gas lasers or solid-state lasers. Laser diodes emit coherent light through stimulated emission within a semiconductor material, typically using a p-n junction to create a population inversion and then stimulating the emission of photons. While they may differ in construction and application from other types of lasers, laser diodes produce coherent and directional light that meets the technical definition of a laser—a device that emits light through a process of optical amplification based on stimulated emission.