What is 3 level laser?

In a three-level laser, the material is first excited to a short-lived high-energy state that spontaneously drops to a somewhat lower-energy state with an unusually long lifetime, called a metastable state. The metastable state is important because it traps and holds the excitation energy, building up a…

What are the drawbacks of a 3 level laser?

Drawback of three level laser system: In the three level laser system, the terminal level is ground level and hence more than half of the atoms are to be transferred to level E2. This requires more pumping power. If the difference of atoms in two levels is small, the power required is also small.

Which laser has four level?

All lasers based on neodymium-doped laser gain media, except those operated on the ground-state transition around 0.9–0.95 μm, are four-level lasers. Neodymium ions can also be directly pumped into the upper laser level, e.g. with pump light around 880 nm for Nd:YAG.

Can we have two level laser?

We can not get population inversion in a 2 level LASER no matter how much we pump the atoms in the ground state. And since population inversion is a necessity for lasing action, we don’t have two level lasers.

What is two level pumping?

Three level pumping Scheme Two level pumping Scheme: This scheme contains only two energy levels i.e., ground state and excited state. The atom absorbs the photon energy and jumps to excited state from ground state. Introducing another one energy state in between the ground state and excited may solve this problem.

Why are 4 level laser better than 3 level laser?

The pumping operation of a four level laser is similar to the pumping of a three level laser. The advantage of the four level laser is the low population of the lower laser energy level (E2). To create population inversion, there is no need to pump more than 50% of the atoms to the upper laser level.