Learning Forum

[Amiiiiho]

Hello

I want to simulate quantum dot photodector, but i dont know how i can define quantum dots in lumerical FDTD !

Does lumerical consider the sphere with 5 nm radius as quantum dot ? Or some special setting should be down for defining quantum dot ?

Please help me. Thank you

[Guilin Sun]

In FDTD, the material (and the geometric shape) determines the physics of the device.

Thus Lumericla FDTD does not specify the diameter as quantum dot. Depending on your device and simulation goal, you may use dipole, or small sphere to represent the "quantum dot".

Please refer:

Quantum dot laser using 4-level 2-electron material

Greens function and local density of states of a dipole source

 

[Amiiiiho]

Thank you for your help and reply????????.

Yes i mean is if i use a small sphere, will lumerical consider it as quantum dot?

My device is photodector and i use plane wave source as optical source and i want to optimize tha absorption by using quantum dot.

[Guilin Sun]

As replied before, Lumerical FDTD does not have a quantum dot object. However as long you believe such a small sphere can represent it, with proper material property, FDTD can simulate it without any issue, provided that it can be well resolved, and its material property can describe the physics.

You use a plane wave for a single quantum dot with PML BCs? if there is only one, isolated quantum dot without periodicity, please use TFSF source. Plane wave source will be truncated by PML and will have diffraction.

https://optics.ansys.com/hc/en-us/articles/360034382874-Understanding-field-truncation-issues-with-finite-sized-plane-wave-sources

https://optics.ansys.com/hc/en-us/articles/360034382934-Tips-and-best-practices-when-using-the-FDTD-TFSF-source

https://optics.ansys.com/hc/en-us/articles/360034902133-Understanding-source-normalization-in-the-TFSF-source

 

 

 

[Amiiiiho]

I have array of quantum dots, but i define one quantum dot  with periodicity. In this situation, which soure is correct ?

And also i have another question: is it possible to see quantized bandstructure in lumerical ? And is it possible to see wave function diagram in lumerical ?

I mean i want to be assued that when i  define a small sphere in lumerical, the lumerical consider it as quantum dot.