Laser pumping: further increasing injection above threshold?

This information can be found in section 11.5 of the handout on Semiconductor Optoelectronics by Farhan Rana from Cornell University.
  • #1
Xiu Liu
1
0
Above the threshold, the stimulation emission becomes dominant for lasing. If increasing the pumping, what will be the change of spontaneous emission and its contribution to the output power and FWHM of the signal, based on the threshold carrier density clamping and the threshold gain clamping, leading to the non-linear effect?

My question arises from the handout of Semiconductor Optoelectronics (Farhan Rana, Cornell University ) at section 11.5 and I am quite curious about the situation if further increasing the injection.

https://courses.cit.cornell.edu/ece533/Lectures/handout11.pdf

Many thanks
 
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  • #2
Above the threshold, the contribution of spontaneous emission to the total output power and the FWHM of the signal will decrease as the pumping is increased. The reason for this is that as the number of carriers in the active region increases, the gain of the device will increase, which will result in stimulated emission becoming more dominant than spontaneous emission. As a result, the contribution of spontaneous emission to the total output power and FWHM of the signal will decrease. Additionally, the non-linear effect of threshold carrier density clamping and threshold gain clamping will cause the output power and FWHM of the signal to saturate at higher pump powers.
 

1. What is laser pumping and how does it work?

Laser pumping is the process of increasing the energy level of atoms or molecules in a laser medium to stimulate the emission of coherent light. This is typically done by applying an external energy source, such as an electrical current or another laser beam, to the laser medium.

2. What is the purpose of further increasing injection above threshold in laser pumping?

The threshold is the minimum energy level needed for a laser to produce a sustained output of light. By increasing the injection above this threshold, the laser can produce a stronger and more stable output of light, making it more effective for various applications.

3. What are the methods for increasing injection above threshold in laser pumping?

There are several methods for increasing injection above threshold, including increasing the pump power, using a more efficient laser medium, and optimizing the laser cavity design. These methods can also be combined to achieve even higher injection levels.

4. Are there any risks or drawbacks to increasing injection above threshold in laser pumping?

Increasing injection above threshold can potentially lead to thermal effects, which can cause damage to the laser medium or affect the output of the laser. It is important to carefully monitor and control the injection level to avoid these risks.

5. What applications benefit from further increasing injection above threshold in laser pumping?

High-power lasers used in industrial cutting and welding, laser spectroscopy, and laser-based medical treatments all benefit from increased injection above threshold. It allows for more precise and powerful laser output, making these applications more efficient and effective.

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