Fiber laser fiber has a wide range of applications, including laser fiber communication, laser space long-distance communication, industrial shipbuilding, automobile manufacturing, laser engraving, laser marking, laser cutting, printing roll, metal non-metallic drilling/cutting/welding (brazing, quenching, cladding and deep welding), medical equipment and equipment, large-scale infrastructure, as the pump source of other lasers, etc.

Fiber laser refers to the laser using rare earth doped glass fiber as the gain medium. Fiber laser can be developed on the basis of fiber amplifier. Under the action of pump light, it is easy to increase the formation success rate density in the fiber, causing the "particle number inversion" of the laser energy level of the laser working material. When a positive feedback loop is properly added (forming a resonator), the laser oscillation output can be formed.

Structure of fiber laser

The generation of laser signal requires three basic conditions: particle number inversion, optical feedback and reaching laser threshold. Therefore, the laser is composed of three parts: working material, pump source and resonant cavity. The basic structure of the fiber laser is as follows: the gain fiber is the gain medium that generates photons; The role of the pump light is as an external energy to make the gain medium achieve the particle number inversion, that is, the pump source; The optical resonator consists of two mirrors, which are used to feedback photons and amplify them in the working medium. The pump light is absorbed after entering the gain fiber, which makes the number of energy level particles in the gain medium reverse. When the gain in the resonant cavity is higher than the loss, laser oscillation will be formed between the two mirrors, generating laser signal output.

(1) Good beam quality.

The waveguide structure of the fiber determines that the fiber laser is easy to obtain single transverse mode output, and is little affected by external factors, so it can achieve high brightness laser output.

(2) High efficiency.

Fiber laser can achieve high light to light conversion efficiency by selecting a laser with emission wavelength matching the absorption characteristics of doped rare earth elements as the pump source. For Yb doped high power fiber lasers, 915 nm or 975 nm lasers are generally selected, which have a long fluorescence life and can effectively store energy to achieve high power operation. The overall electro-optical efficiency of commercial fiber lasers is as high as 25%, which is conducive to reducing costs, energy conservation and environmental protection.

(3) Good heat dissipation characteristics.

Fiber laser uses long and thin rare earth doped fiber as laser gain medium, and its surface area and volume ratio are very large. It is about 1000 times that of solid block laser, and has natural advantages in heat dissipation. No special cooling is required for the optical fiber in the case of medium and low power, and water cooling is used in the case of high power, which can also effectively avoid the decline of beam quality and efficiency caused by thermal effects, which are common in solid-state lasers.

(4) Compact structure and high reliability.

Because the fiber laser uses small and soft fiber as the laser gain medium, it is beneficial to compress the volume and save the cost. The pump source is also a laser that is small in size and easy to be modularized. Commercial products can generally be output with pigtails. In combination with fiber optic devices such as fiber Bragg gratings, as long as these devices are fused to each other, full optical fiber can be achieved. It has high immunity to environmental disturbances, high stability, and can save maintenance time and costs.