What Are Pulsed Lasers?
Pulsed lasers are devices that emit laser light in short bursts or pulses rather than continuously. These pulses can vary in duration, ranging from nanoseconds to femtoseconds, and are defined by specific parameters such as energy, pulse width, frequency, and wavelength.
Applications of Pulsed Lasers
Pulsed lasers have diverse applications across various fields, including industrial, medical, and scientific sectors. Their uses include microfabrication tasks like drilling and scribing, marking and surface modification, acting as oscillators in laser processing machines, dermatological treatments, medical surgery tools, LIDAR technology, non-destructive inspection, laser fusion, microscopy, laser ablation, and processing MEMS with ultrashort pulses.
Principles of Pulsed Lasers
The generation of pulsed laser light can be achieved through several methods:
- Direct Modulation: This method involves manipulating a continuously oscillating light by switching a shutter on and off or adjusting the electrical current to control the pulse shape.
- Q-Switching: Utilizes an inverted population distribution to increase light intensity inside the resonator, creating high-energy pulses by temporarily enhancing the resonator’s Q-value.
- Mode-Locking: Synchronizes the longitudinal modes of the laser’s spectrum to produce short pulses, ideal for generating femtosecond and picosecond laser pulses.
Types of Pulsed Lasers
Pulsed lasers can be categorized based on the type of resonator used:
- Solid-State Lasers: Utilize a solid crystal as the resonator, such as YAG lasers, enabling high outputs even with compact resonators.
- Gas Lasers: Use a mixture of gases like helium and nitrogen as the medium, capable of achieving high laser power due to the scalability of the resonator.
- Optical Fiber Lasers: Transmit light through optical fibers, minimizing light loss, and are commonly used in industrial applications.
Additional Insights on Pulsed Lasers
Ultrashort Pulsed Lasers
Ultrashort pulsed lasers emit wavelengths shorter than those typically associated with lasers, reaching into the pico- and femto-second ranges. Characterized by their significant power output, these lasers minimize thermal melting during processing, enabling precise pattern creation on metal surfaces with reduced thermal effects. Continuous advancements are improving processing speeds, addressing one of the initial drawbacks of laser usage.