Laser is one of the core components of fiber laser cutting machine. With the development of laser processing technology, many new lasers have emerged. According to the working medium, lasers can be divided into four categories: gas lasers, solid lasers, semiconductor lasers and dye lasers.

Semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as working materials. It has the characteristics of small size and long life, and can be pumped by a simple injection current method. Its working voltage and current are compatible with integrated circuits, so it can be integrated with it on a single chip. Semiconductor diode lasers have been widely used in laser communications, optical storage, optical gyroscopes, laser printing, ranging, and radar.

So, what is the luminescence principle and working principle of semiconductor lasers in fiber laser cutting machines?

1. The luminescence principle of the laser of the fiber laser cutting machine

The conditions that the laser of the fiber laser cutting machine must meet to generate lasers are particle number inversion; there must be a resonant cavity that can play a role in light feedback to form laser oscillation; the formation forms are diverse, and the simplest is the Fabry-Perot resonant cavity. The generation of lasers must also meet the threshold condition, that is, the gain must be greater than the total loss.

In order to form a stable oscillation, the laser medium must be able to provide a sufficiently large gain to compensate for the optical loss caused by the resonant cavity and the loss caused by the laser output from the cavity surface, and continuously increase the light field in the cavity. There must be a sufficiently strong current injection, that is, there must be enough particle number inversion. The higher the particle number inversion, the greater the gain obtained, that is, a certain current threshold condition must be met. When the laser reaches the threshold, light with a specific wavelength can resonate and be amplified in the cavity, and finally form a laser and output continuously.

2. Characteristics of semiconductor lasers

Semiconductor lasers were born in 1962 and are a type of laser device that uses semiconductor materials as working materials. Semiconductor lasers have small size and light weight; low driving power and current; high efficiency and long working life; can be directly electrically modulated; easy to realize optoelectronic integration with various optoelectronic devices; compatible with semiconductor manufacturing technology; can be mass-produced. It has become the fastest-growing, most widely used, earliest to go out of the laboratory and achieve commercialization and the largest output value in the world.

3. Working principle of semiconductor laser

The working principle of semiconductor laser is the excitation mode, which uses semiconductor materials (i.e., electrons) to emit light by transition between energy bands, and uses the cleavage surface of semiconductor crystal to form two parallel reflective mirrors as reflectors to form a resonant cavity, so that light oscillates and feedbacks, produces radiation amplification of light, and outputs laser.

Semiconductor lasers work by injecting carriers, and must produce enough particle number inversion distribution, that is, the number of particles in high energy state is sufficiently greater than the number of particles in low energy state; there must be a suitable resonant cavity that can play a feedback role, so that stimulated radiation photons proliferate, thereby generating laser oscillation; certain threshold conditions must be met so that the photon gain is equal to or greater than the photon loss.

The above is the analysis of the luminescence principle and working principle of semiconductor lasers in fiber laser cutting machines.