Can we make a circular polarization laser directly?

In summary, it is theoretically possible to create a circular polarization laser by using a pump light source with circular polarization. However, in practice, this may be difficult to achieve due to induced birefringence in the gain medium when its temperature increases. Pumping with linear polarization does not induce birefringence, but rather the heating process itself causes this effect. Additionally, the polarization of the pump does not affect the output of the laser, as the excited atoms in the gain medium store energy that is released through stimulated emission. To create a circularly polarized output, it may be necessary to manipulate the output beam rather than the cavity of the laser.
  • #1
Now,we get the circular polarization photon using 1/4 waveplate, can we make a circular polarization laser directly through Stimulated Emission Radiation?
or, when a electron transition from one level to another level,what kind of polarization of the photon, linear or circular?
thank you!
 
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  • #2
Theoretically you can if you also provide pump light source with circular polarization. But in practice, it may not be that easily realizable. A first obstacle I can identify is the induced birefringence in the gain medium when its temperature starts increasing. Even if the pump source is circularly polarized (or any polarization), the output does not exactly have the same polarization state as the pump due to the modification inside the gain medium itself.
 
  • #3
blue_leaf77 said:
Theoretically you can if you also provide pump light source with circular polarization. But in practice, it may not be that easily realizable. A first obstacle I can identify is the induced birefringence in the gain medium when its temperature starts increasing. Even if the pump source is circularly polarized (or any polarization), the output does not exactly have the same polarization state as the pump due to the modification inside the gain medium itself.
thank you,why linear polarization pump don not induced birefringence in the gain medium?
 
  • #4
It's the heating procsee induces birefringence, not the polarization. Pump with any polarization will identically cause heating in the gain medium and if this is not mitgated, above certain temperature the birefringence effect will become significant.
 
  • #5
Heating effects aside, I don't think using a CP pump has anything to do with the laser output. The pump simply establishes a population inversion. The excited atoms are in a metastable state with a long lifetime, so they store energy that can be put into the output beam through stimulated emission. All memory of the pump process is lost. You would need to find a laser medium that emits a CP wave when it drops to the ground state.

EDIT: I think that means that the cavity must have resonate with CP, which probably means inserting materials into it that would kill the resonator Q. Probably better to manipulate the output beam.
 
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1. Can we make a circular polarization laser directly?

Yes, it is possible to make a circular polarization laser directly. Circular polarization is achieved by introducing a quarter-wave plate into the laser cavity, which converts linearly polarized light into circularly polarized light. This can be done in the design of the laser itself, rather than having to modify an existing linearly polarized laser.

2. How does circular polarization differ from linear polarization in lasers?

Circular polarization differs from linear polarization in the orientation of the electromagnetic wave. In linear polarization, the electric field oscillates in one plane, while in circular polarization, the electric field rotates in a circular motion. This results in different properties and behaviors of the laser light, such as the direction of rotation and the ability to interact with chiral molecules.

3. What are some applications of circular polarization lasers?

Circular polarization lasers have a variety of applications, including in spectroscopy, microscopy, and optical communications. They are also useful in medical procedures, such as laser eye surgery, and in the study of chiral molecules, which have different properties depending on the direction of circular polarization.

4. Is circular polarization necessary for all laser applications?

No, circular polarization is not necessary for all laser applications. In some cases, linearly polarized lasers may be more suitable or cost-effective. However, circular polarization can provide unique advantages in certain applications, such as in studying chiral molecules or improving the precision of optical measurements.

5. How can we control the degree of circular polarization in a laser?

The degree of circular polarization in a laser can be controlled by adjusting the alignment and thickness of the quarter-wave plate within the laser cavity. By fine-tuning these parameters, the ratio of left and right circularly polarized light can be adjusted, resulting in a desired degree of circular polarization. Other factors, such as the orientation and material of the laser's gain medium, can also affect the degree of circular polarization.

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