How Do You Extract the L-I Curve from Semiconductor Laser Rate Equations?

[enjin]

Homework Statement

Hi everyone,

this is not really homework, but I wasn't quite sure where is the best place to post this question.

I am working on semiconductor lasers at the moment, and have solved the rate equations using Matlab. I am curious as to how one is supposed to get the L-I curve out of it. At the moment, the only thing I can think of would be that we just run the codes for a range of input current, and store the corresponding output from it.

However, what if the situation is more tricky, and we now have to modulate the laser? Does anybody have any coding sample, or link, or know how to deal with modulation depth, incorporate it as the input, and then get the L-I out of the whole thing? Or is it still the same as when we deal with just the rate equations with basic current input (ie. non-modulated)?

Any ideas?

 

[Jhero]

Homework Solution

Hello,

Thank you for posting your question here. I am glad to hear that you are working on semiconductor lasers and have successfully solved the rate equations using Matlab. In order to obtain the L-I curve, there are a few steps that you can follow:

1. First, you will need to determine the parameters that affect the L-I curve, such as the carrier lifetime, cavity length, and mirror reflectivity. This information can be found in literature or through experimental measurements.

2. Next, you can use the rate equations to calculate the carrier density and photon density as a function of input current. This will give you the relationship between the carrier density and photon density, which is known as the gain curve.

3. From the gain curve, you can then calculate the threshold current, which is the minimum current required for lasing to occur. This is the point where the gain curve intersects with the loss curve, which can also be calculated from the rate equations.

4. Once you have the threshold current, you can then vary the input current above the threshold to obtain the L-I curve. This can be done by running the codes for a range of input currents, as you mentioned, and plotting the corresponding output power.

As for modulation, you can incorporate it into the rate equations by adding a term for the modulation depth and frequency. This will affect the carrier density and photon density, which in turn will affect the L-I curve. You can then repeat the steps above to obtain the modulated L-I curve.

I hope this helps. If you need further assistance or have any other questions, please feel free to ask. Good luck with your research!