Contents
Source: Kokyo, Inc.
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Continuous-Wave Operation in Lasers
Understanding Continuous-Wave Operation
Continuous-wave (CW) operation of a light source means that it is continuously operated, emitting light without being pulsed. This term is commonly used in lasers and gas discharge lamps.
Continuous-Wave Lasers
For a laser, continuous-wave operation indicates that it is continuously pumped and emits light continuously. The emission can be in a single resonator mode (single-frequency operation) or in multiple modes.
The first continuous-wave laser was a helium-neon laser operating at 1153 nm, followed by versions at the common emission wavelength of 632.8 nm. Various types of lasers, including gas lasers, solid-state lasers, semiconductor lasers, and dye lasers, can operate continuously.
Challenges and Solutions
Some lasers face challenges in achieving continuous-wave operation, especially those with low-gain laser transitions. In such cases, fiber lasers may be preferred over bulk lasers due to higher gain efficiency. Techniques for stabilizing output power and optical frequency are often employed to address power variations and laser noise.
Quasi-Continuous-Wave Operation
In cases where strong heating of the gain medium occurs during continuous-wave operation, lasers may utilize quasi-continuous-wave operation. This method involves switching the pump power on for limited intervals to reduce heating while maintaining steady-state optical conditions.
Continuous-Wave Mode Locking
Continuous-wave mode-locked lasers maintain constant pulse energy or average power without Q-switched mode locking. Despite emitting pulses, mode locking ensures that resonator modes are excited with constant powers.
Conclusion
Continuous-wave operation in lasers is essential for various applications, requiring continuous pumping and emission of light. Understanding the challenges and techniques involved in achieving stable operation is crucial for optimizing laser performance.
Source: ResearchGate
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