Can you obtain laser without metastable state?
Can you obtain the laser without metastable state? Answer from the author: Yes, there are laser gain media which do not have metastable states. This applies to semiconductor gain media and to laser dyes, for example.
What is meant by metastable state?
metastable state, in physics and chemistry, particular excited state of an atom, nucleus, or other system that has a longer lifetime than the ordinary excited states and that generally has a shorter lifetime than the lowest, often stable, energy state, called the ground state.
What is the life time of the metastable state of laser energy level?
The average lifetime before spontaneous emission occurs for a metastable state is on the order of a microsecond to a millisecond, quite a lengthy period of time on the atomic timescale. With lifetimes this long, excited atoms and molecules can produce significant amounts of stimulated emission.
What is meant by the terms laser metastable state and population inversion?
The longer the spontaneous emission lifetime, the more suitable a molecule or atom is for laser applications. In this system, the ground state is the lower laser level, and a population inversion is created between this level and a higher-energy metastable state.
How does a laser achieve a metastable state?
Metastable State in Lasers In a number of gas lasers, helium atoms are excited into metastable states by an electrical discharge. During collisions with other atoms (e.g. neon in a helium-neon laser), they can then transfer or exchange the excitation energy to those atoms.
What causes metastable state?
Metastability in digital systems occurs when two asynchronous signals combine in such a way that their resulting output goes to an indeterminate state. A common example is the case of data violating the setup and hold specifications of a latch or a flip-flop.
Why does metastable state exist?
In a triplet, the unpaired excited electron has the same spin orientation as the unpaired ground electron, so it has to spin flip to get back down. This has a very low probability of occurring which makes the triplet state of let’s say neon, for instance, metastable.
Why does metastable state have longer lifetime?
A common example of metastability in science is isomerisation. Higher energy isomers are long lived because they are prevented from rearranging to their preferred ground state by (possibly large) barriers in the potential energy.
What is metastable state and why it is required to obtain population inversion?
The population of metastable state can exceed the population at a lower level thereby establishing population inversion in a lasing medium. Population inversion could not be created without a metastable state. The metastable electronic state of the solid gain media is same as that of an upper laser level.
What is the role of He in He Ne laser explain the working with a suitable energy level diagram?
Working of He-Ne It is a four energy level laser system. The electrons produced from electric discharge collide with He and Ne atom and excite them to the higher energy levels He2 and Ne4 at 20.61 eV and 20.66 eV respectively. Thus, He atoms help to achieve population inversion in Ne atoms.