Sample interview questions: What are some common techniques for achieving high-energy laser pulses?
Sample answer:
Some common techniques for achieving high-energy laser pulses include:
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Chirped Pulse Amplification (CPA): This technique involves stretching the laser pulse in time using a dispersive element, such as a grating or prism, before amplifying it. The stretched pulse is then amplified to higher energy levels and compressed back to its original duration. CPA allows for efficient energy extraction from the gain medium while avoiding detrimental effects like self-focusing and optical damage.
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Mode-locking: Mode-locked lasers generate ultra-short pulses by actively or passively locking the laser modes together. Active mode-locking typically uses an external modulator to create a periodic modulation in the laser gain, resulting in a train of ultrashort pulses. Passive mode-locking relies on the use of saturable absorbers or nonlinear optical effects to achieve self-starting, stable mode-locking.
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Optical Parametric Chirped Pulse Amplification (OPCPA): OPCPA is an alternative to traditional CPA that utilizes nonlinear optical processes. In OPCPA, the initial laser pulse is amplified by a nonlinear crystal, which converts it to a longer wavelength. Subsequent amplification and temporal compression of the pulse then occur at the longer wavelength, followed by frequency conversion back to the desired wavelength. OPCPA offers advantages in terms of scalability, broad wavelength tunability, and high peak powers.
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Multi-pass amplification: Th… Read full answer