Solid State Lasers

laser = Light Amplification by Stimulated Emission of radiation

Common lasers are like this

A stray emitted photon is able to cause another photon to be emitted by stimulating an inverted state in another atom. This emission will be precisely parallel to the stimulating one, and this carries on. Since light goes fast it soon leaves the area....unless it hits a mirror and is reflected back through the excited area again and on the other side, another mirror and back and forthe it goes mkaing more emissions with time untill the inversion is depleted and the beam dissipates by relective losses and absorption by depleted atoms. By choosing your mirrors you can get part of the beam to exit one mirror and with continuous pumping you maintain the inversion. This give you a continuous, or often a pseudo continuous laser that starts and stops at a very high rate.

Quantum well differ

http://ece-www.colorado.edu/~bart/book/movie/movie1.htm

drill down here for details on other stuff

http://www.google.com/search?hl=en&sa=X&oi=spell&resnum=0&ct=result&cd=1&q=%22quantum+well%22+%2Blaser+%2Bprinciples&spell=1

Hey thanks that was a very good site, now it makes sense how they work. Though will still have to read more into the eV part.

Matt

The operative phrase here is "stimulated emission of radiation." When a laser substance is excited, particular electrons of atoms or molecules all raise to the same energy state above ground state. This is the "population inversion" that you've heard people talking about. At some point, an electron drops to ground state and gives off a photon. If this photon passes near another "excited electron" it can cause that electron to spontaneously emit a photon and drop to ground state, as well. In a tuned cavity with mirrors, you want these photons to go back-and-forth causing more electrons to spontaneously emit, and causing a cascade of emitted photons, until the light becomes so intense that part of it can overcome and exit the output coupler mirror and exit the cavity as a laser beam.

With solid state diode lasers, I believe the same thing happens, but instead of electrons of an atom, the population inversion occurs with free electrons in excited states. Hence one of the odd things about diode lasers... Their light isn't usually coherent as with other lasers. To make diode laser light coherent, you have to do a lot of secondary optical "massaging" to get the light back into phase. There's also problems with large differences in the polarization between the vertical and horizontal axes. Laser light from diode lasers is usually elliptically polarized, which means the electric field of the emitted light beam is going in-and-out of phase with respect to the beam in-total. They make optics that put this right by circularly polarizing the light.

Any help?

wow thats alot. i got a job working in mbe and would like to know alot about whats going on b4 i get there. this way i'll have less to learn and hopefully get a bigger 90 raise.

thanks again,

Matt