Why is the birth of semiconductor lasers so that optical fibers have been valued?

Is that the case? Seventy percent of the cost of fiber lasers comes from semiconductor lasers.

Semiconductors can be linked: the transformation of signals and optics for optical communication.

In short, they emit different dielectric materials. The gain medium used in fiber lasers is optical fiber, and the gain medium used in semiconductor lasers is semiconductor materials, generally gallium arsenide, indium gallium, etc. (Similarly, the gain medium of solid-state lasers is generally crystal, glass, ceramic, etc.)

Gases are made using helium, neon, carbon dioxide, etc. The luminescence mechanism of semiconductor lasers is that particles transition between the conduction band and valence band to produce photons, and because they are semiconductors, electrical excitation can be used, which is a direct electro-optic conversion. However, optical fiber cannot directly realize electro-optical conversion, and needs to use light to pump the gain medium (generally pumped with a laser diode), which realizes optical conversion.

Fiber lasers have good heat dissipation, and generally air cooling is sufficient. Semiconductor lasers are very affected by temperature, and when the power is large, they need to be cooled by water.

According to the working medium, lasers can be divided into four categories: gas lasers, solid-state lasers, semiconductor lasers and dye lasers. Among them, semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as working materials. Semiconductor lasers have a wide range of applications in laser communication, optical storage, optical gyroscope, laser printing, ranging and radar.

The fiber laser you asked about is the application of semiconductor lasers in the field of laser communication.

There are various ways to classify semiconductor lasers. According to wavelength: medium and far infrared lasers, near-infrared lasers, visible lasers, ultraviolet lasers, etc.; By structure:

Double heterojunction lasers, large cavity lasers, distributed feedback lasers, vertical cavity surface emitting lasers; According to the application field: optical communication lasers, optical storage lasers, high-power pump lasers, traction pulse lasers, etc.; According to the combination of tube cores, it is divided into: single tube, array (line array, area array); According to the working mode of injection current, it is divided into:

Pulsed, continuous, quasi-continuous, etc.

Semiconductor laser has a wide range of applications, such as laser cutting, laser welding, laser marking, laser drilling, laser engraving, laser medical, laser beauty, laser display, laser holography, laser phototypesetting, laser refrigeration, laser detection and laser measurement, etc.

The biggest disadvantage of semiconductor lasers is that the laser performance is greatly affected by temperature, such as gallium arsenide lasers, when the temperature changes from absolute temperature 77°K to room temperature, the laser wavelength changes from microns. In addition, although the efficiency is high, due to the small size, the total power is not high, the continuous output at room temperature is only a few tens of milliwatts, and the pulse output is only a few watts to tens of watts.

The divergence angle of the beam is generally between a few degrees and 20 degrees, so it is inferior in directionality, monochromacy and coherence.