Author Question: A four-level system of transitions in a laser employs a few key methods to produce coherent laser ... (Read 100 times)

jake · **on:** Jul 28, 2018

A four-level system of transitions in a laser employs a few key methods to produce coherent laser light. All of the following are vital to the four-level systems' working EXCEPT:
a. forbidden transitions
b. metastable states
c. tunable emission wavelengths
d. external source of energy
e. population inversion

Question 2

A magnet of solid metal is placed in a magnetic field. Within the magnet, the magnetic field is greater than that outside (but still oriented in the same direction). The magnet is then heated by an external source to a very high temperature. The magnetic field inside the magnet is now significantly weaker but still greater than the outside field. What kind of magnet is this?

mk6555 · **Reply #1 on:** Jul 28, 2018

Answer to Question 1

Although the ability to tune the wavelengths of output of the laser is useful in many scientific applications, it is not a necessary feature of the four-level system.
c.

Answer to Question 2

It is impossible to tell between a ferromagnet and paramagnet in this case. When place in an external magnetic field, both the ferromagnet and paramagnet could have a greater internal field than outside. When heated past the Curie point for a ferromagnet, the ferromagnet becomes a paramagnet with lesser magnetization. Also, the paramagnet's magnetization is inversely proportional to the temperature.
e.