The compact size and overall size is an order of magnitude smaller than conventional CO2 or YAG laser systems, making it extremely mobile. The lifetime of the semiconductor pump source is estimated at over 100,000 hours, eliminating the need to replace the semiconductor source at all.
Because Nd:YAG is a four-energy-level system with high quantum efficiency and a large area of excited radiation, its threshold is much lower than that of ruby and neodymium glass. Nd:YAG crystal has excellent thermal properties, so it is very suitable for continuous and heavy frequency devices. It is currently the only solid working substance that can work continuously at room temperature, and in small and medium power pulsed devices, the current application of Nd:YAG far exceeds that of other working substances.
Like other solid-state lasers, YAG lasers consist of a working laser material, a pump source and a resonant cavity. However, due to different types of activation ions doped in the crystal, different pumping sources and pumping methods, the structure of the resonant cavity, as well as the use of other functional structure of different devices, YAG lasers can be divided into a variety of, for example, according to the output waveform can be divided into continuous-wave YAG lasers, heavy-frequency YAG lasers, and pulsed lasers, etc.; according to the wavelength of the work of the division of the 1.06 μm YAG lasers, Frequency-doubled YAG lasers, Raman frequency-shifted YAG lasers (λ = 1.54 μm) and tunable YAG lasers (such as color-centered lasers), etc.; according to the different doping can be divided into Nd: YAG lasers, Ho-doped, Tm, Er, etc., YAG laser; the shape of the crystal is divided into different rod and slat-shaped YAG laser; according to the different output powers (energies) can be divided into high and medium power and small and medium power YAG lasers. According to the different output power (energy), can be divided into high-power and small and medium-power YAG lasers and so on. All kinds of YAG lasers, solid-state lasers become one of the most important branch.
The structure of a fiber laser is the same as that of traditional solid-state and gas lasers. Fiber laser is basically by the pump source, gain medium, resonant cavity three basic elements. Pump source is generally used in high-power semiconductor lasers (LD), gain medium for rare earth doped fiber or ordinary nonlinear fiber, resonant cavity can be formed by optical feedback components such as fiber grating various linear resonant cavity, can also be composed of a variety of coupler toroidal resonant cavity pump light through the appropriate optical system coupling into the gain fiber, gain fiber in the absorption of pump light to form the number of particles or nonlinear gain and the formation of spontaneous radiation generated by spontaneous radiation. Generate spontaneous radiation generated by the spontaneous radiation light amplified by the excitation and resonant cavity mode selection. The final formation of stabilized laser output.
The fiber laser has two types of excitation state, one is the three energy levels of excitation, the other is the four energy levels of excitation. The difference between the two is the location of the lower energy level in the three-level system, the laser level that is the ground state, or very close to the ground state of the energy level. In a four-level system, there is still a jump, usually non-radiative, between the lower laser level and the ground state. Electrons from the ground state elevated to higher than the laser on the energy level of one or more pumping band, electrons generally through non-radiative leaps to reach the laser on the energy level of the pumping band of electrons quickly relaxed to a long-lived substable state, the accumulation of electrons in the substable state caused by the number of electrons more than the laser down to the energy level, that is, the formation of the number of particles in the inverse. Electrons in the form of radiated photons to release energy back to the ground state of this spontaneous emission of photons by the optical resonance cavity feedback back to the gain medium induced stimulated emission, the production of photons to induce this process with the complete nature of the photon.