The Bragg mirror is composed of alternating Si02 and Ti02 coatings, and the refractive index of the coating changes stepwise. Such a structure introduces a negative dispersion relationship. The front of the mirror is like a transmission grating that produces partially reflected light, while the back of the mirror produces Bragg reflection. In order to eliminate the shock effect, the thickness of the high refractive index layer is made into a cone shape, and the front of the mirror is coated with a broadband anti-reflection layer. Mirror on the net keeps rising and looking for regular play and shooting layer. The compressor cannot adjust the dispersion. It must be manufactured and accurately cut according to standards, and must be manufactured by ion beam sputtering technology.
Therefore, the price is quite expensive and it is not widely used. The fourth type is a micro-mechanical deformable mirror compressor using new technology. In addition to bandwidth-limited pulses, active devices such as liquid crystal modulators, acousto-optic modulators, and mechanical deformation mirrors (M2) can all be used to generate complex waveforms. Femtosecond green laser pointer is a kind of laser that operates in pulse form. The duration is very short, only a few femtoseconds. A femtosecond is 10 to the minus 15th power of a second, which is 1/1000 trillion seconds. The shortest pulse obtained by the method is several thousand times shorter, which is the shortest pulse that humans can currently obtain under experimental conditions. This is the first feature of femtosecond lasers.
The second feature of femtosecond laser is that it has a very high instantaneous power, which can reach one trillion watts, which is a hundred times more than the current total power generation in the world. The third feature of the femtosecond laser is that it can focus to a space area smaller than the diameter of a hair, making the electromagnetic field stronger than the force of the nucleus on the surrounding electrons several times higher. How are these characteristics of femtosecond laser realized? The high-power femtosecond laser system consists of four parts: oscillator, stretcher, amplifier and compressor. In the oscillator, a special technique is used to obtain femtosecond laser pulses. The stretcher stretches the femtosecond seed pulse in time according to different wavelengths.
The amplifier makes this stretched pulse get sufficient energy. The compressor converges the amplified spectra of different components together and restores it to the femtosecond width, thereby forming a femtosecond laser pointer pulse with extremely high instantaneous power. Femtosecond lasers have been widely used in physics, biology, chemical control reactions, optical communications and other fields. It is particularly worth mentioning that due to the fast and high-resolution characteristics of femtosecond lasers, it has unique advantages and irreplaceable advantages in the early diagnosis of lesions, medical imaging and biological detection, surgical treatment and the manufacture of ultra-small satellites. The role of.