Lasers are optical devices used in a variety of applications, from surgery to communication. The mode of operation of a laser is essential to understanding its behavior and specific uses. In this detailed article, we'll explore in depth the four main laser operating modes: Continuous, Relaxed, Q-switched and Blocked mode. We'll look at the basic principles of each mode, their distinctive features and their applications in different fields.
1. Continuous mode (or CW):
- Operating principle: The laser operates continuously, emitting a constant beam of light without interruption.
- Features: Constant, continuous output power, suitable for applications requiring a continuous laser beam, such as engraving, cutting and lighting.
- Applications: Industrial engraving, material cutting, precision measurement, high-speed optical communication.
We're now going to take a look at pulsed lasers.
2. Q-switched mode :
- Operating principle: Accumulation of laser energy in the laser cavity over a relatively long period of time, followed by sudden release.
- Characteristics: Emission of very short, intense light pulses with high peak powers.
- Applications: Eye surgery, tattooing and tattoo removal, photodisruption (tissue fragmentation), selective photothermy.
3. Locked-Mode :
- Operating principle: Synchronization of the laser's longitudinal modes to produce extremely short laser pulses.
- Characteristics: Ultra-short light pulses with femtosecond or picosecond durations and high peak powers.
- Applications: Femtosecond spectroscopy, high-energy laser research, time-resolved metrology, nanostructure fabrication.
Conclusion
The different laser operating modes offer unique features tailored to specific applications. Continuous mode is used for applications requiring a constant laser beam, while Q-switched mode produces short, intense pulses. Q-switched mode generates even shorter, more energetic pulses, while mode-locked delivers ultra-short, powerful pulses. Understanding these different modes is essential for choosing the right laser in fields such as surgery, scientific research, fine engraving and spectroscopy. Lasers continue to play a crucial role in modern society, pushing back the boundaries of science and technology.