Laser Transitions and Pumping Methods

Spontaneous emission occurs randomly and independently of external factors, while stimulated emission is triggered by incident radiation.

Pumping involves providing energy to the laser medium to excite the atoms or molecules to higher energy levels, leading to population inversion.

The threshold condition for lasing is achieved when the rate of stimulated emission becomes greater than the rate of losses in the laser cavity.

<p>In a He-Ne laser, electrical pumping involves ionizing helium molecules and accelerating them with an electric field to excite the atoms.</p> Signup and view all the answers

<p>Population inversion ensures that there are more atoms or molecules in the excited state than in the ground state, allowing for stimulated emission to dominate over absorption.</p> Signup and view all the answers

<p>A three-level pumping scheme involves using three energy levels, typically found in lasers like the Ruby laser.</p> Signup and view all the answers

<p>In diode lasers, the conduction band and valence band play a crucial role in achieving population inversion through electrical current.</p> Signup and view all the answers

<p>Ruby lasers use optical pumping with a flash lamp surrounding the Ruby crystal, while He-Ne lasers use electrical pumping with ionized helium molecules accelerated by an electric field.</p> Signup and view all the answers

<p>Four-level pumping schemes are used to ensure a higher efficiency of population inversion and to minimize non-radiative losses in the lasing process.</p> Signup and view all the answers

<p>Diode lasers achieve pumping through direct conversion of electrical current, involving the conduction and valence bands, without the need for external pumping sources.</p> Signup and view all the answers