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The legendary father of laser: How did Gordon Goode uncover the mystery of Q modulation?
In the world of laser technology, Q-switching is undoubtedly one of the most revolutionary inventions. This technology enables lasers to generate pulses up to kilowatts, opening up a wide range of laser applications. The starting point of all this is primarily attributed to scientist Gordon Goode, who first proposed the concept of Q modulation in 1958 and laid the foundation for subsequent experiments.
The core of Q modulation is to adjust the quality factor (Q factor) of the optical resonant cavity inside the laser. The higher the quality factor, the lower the loss of the laser and the stronger its effect.
Principle of Q modulation
The basic principle of Q modulation is to place a variable attenuator inside the optical resonant cavity of the laser. Through the adjustment of this attenuator, the photons generated in the laser cannot return to the gain medium. This prevents the laser from occurring. When the laser medium is continuously pumped, the feedback of the light will be blocked, causing the energy to gradually accumulate inside the gain medium until it reaches a certain critical value. At this time, the laser feedback begins by rapidly changing the state of the attenuator, generating A light pulse is thus formed.
Types of Q Modulation
Q modulation can be mainly divided into active Q modulation and passive Q modulation. Active Q modulation uses an externally controlled variable attenuator to control the generation of pulses using a mechanical device or some kind of modulation device. Passive Q modulation, on the other hand, uses saturable absorber materials, a type of material that has the ability to transmit more light once the light intensity exceeds a certain critical value.
The two modulation techniques are sometimes used in combination to achieve better performance. For example, in active modulation, a beam of external light can be "seeded" so that the resulting pulses have specific characteristics.
Applications of Q modulation
Today, the application of Q-modulated lasers has spread to many fields, including but not limited to metal processing, pulse holography technology, and chemical kinetics research. For example, Q-modulated lasers are able to provide intense light pulses in a short period of time, which is essential for high-precision distance measurement and skin treatments (such as removing tattoos and skin spots).
In skin treatment, Nd:YAG lasers are widely favored due to their powerful pulse performance and affordability. They can effectively break down ink particles and remove them through the body's lymphatic system.
Future Challenges and Possibilities
With the development of science and technology, a fundamental understanding of the principles of Q modulation will further promote the advancement of laser technology. The challenge today is to reduce system complexity while maintaining performance. The introduction of new technologies such as picosecond lasers has made the prospects for laser applications brighter, especially in the removal of difficult colors such as green and light blue.
Conclusion
In short, Gordon Goode's Q modulation theory not only changed our understanding of lasers, but also made it possible for the birth of countless technologies. How will future technology continue to develop on this basis? Perhaps this will become our common goal of exploration.
