Can you explain the basic principles of laser physics?

Sample interview questions: Can you explain the basic principles of laser physics?

Sample answer:

1. Light Amplification by Stimulated Emission of Radiation (LASER):

   • Laser works based on the principle of stimulated emission, where excited atoms emit light photons in a synchronized and coherent manner.

2. Laser Gain Medium:

   • The core component of a laser system is the gain medium, which can be a solid, liquid, gas, or semiconductor material.
   • The gain medium is excited to a higher energy state using an external energy source like an electrical discharge, flash lamp, or another laser beam.

3. Stimulated Emission and Coherence:

   • When an excited atom interacts with a photon of the same frequency, it releases an additional photon through a process called stimulated emission.
   • These emitted photons are in phase with the stimulating photon, resulting in coherent light with a narrow spectral linewidth.

4. Optical Resonator:

   • A laser cavity consists of two reflective mirrors placed at opposite ends of the gain medium.
   • The mirrors reflect the emitted photons back and forth, causing multiple passes through the gain medium.
   • This amplification process leads to the generation of an intense, collimated, and monochromatic laser beam.

5. Population Inversion:

   • The gain medium must be in a state of population inversion, where the number of excited atoms exceeds the number of atoms in the ground state.
   • This condition is achieved through various techniques, such as optical pumping or electrical excitation.

6. Output Coupling:

   • To extract the generated laser beam from the laser cavity, one mirror is partially reflective.
   • This allows a portion of the light to escape the cavity as the output beam while maintaining sufficient feedback for laser operation.

7. Laser Wavelength and Tuning:

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