Lecture 1 Flashcards
What does LASER stand for
Light, amplification by stimulated emission of radiation
What is a laser
An oscillator rather than a simple amplifier
What is an oscillator
An oscillator has positive feedback in addition to amplification.
How is amplification obtained
Through a process known as population inversion
What is population inversion
Population inversion is a non-equilibrium state (a system in thermal equilibrium can not exhibit population inversion)
How is population inversion obtained
Population inversion is attained in a pair of energy levels in a Gain medium.
Two essential components of a laser
Gain medium and a laser cavity.
What is the laser cavity
The laser cavity, allows the accumulation of photons that stimulate emission in the gain medium.
How do lasers work
Laser radiation initially builds up via spontaneous emission. Once the photon population density is substantial , stimulated emission from the gain medium in which population inversion has been attained dominates .
Laser radiation equation
V_R = (E_2-E_1)/h(bar)
What is the Ruby laser made of
Laser medium is a rod of Al2O3 doped with 0.05% of Cr(Ruby)
What does Cr do in the ruby laser
Cr3+ ions replace Al ions in the lattice and provide the energy levels for the lazing transitions.
