Difference between Second-harmonic generation and Two-photon absorption?

[Dean]

Dear all,
I am confused about the Difference between Second-harmonic generation and Two-photon absorption?
Can anyone describe the two phenomena briefly in physical picture?
Thanks a lot.

[Daniele Varsano]

Dear Yimin,
do you have a specific question regarding Yambo implementation on the topic?
For general questions, I strongly suggest you to look at the literature on the topic, textbooks, and discuss with your research group, as the forum is meant to provide support to the use of the code. Improtantly, the forum will be not very effective in this respect and certainly cannot replace the learning process on this issue and in general on the understanding of physical phenomena.

Best,
Daniele

[myrta gruning]

They are substantially different phenomena. You can look at the Boyd classic book on Nonlinear optics or even I like Element of nonlinear optics of Butcher and Cotter or Introduction to Nonlinear Optics of New.

[Dean]

Thanks for your suggestion. I will read some books.
Then, how to calculate two-photon absorption using Yambo?

[claudio]

Dear Yimin

calculation of two-photon absorption is quite complicated, you have to
perform different calculations with different intensities of the external field
and then combine the results to extract it.
You can have a look at this paper:

https://journals.aps.org/prb/abstract/1 ... .98.165126

in section III we explain how to do it
best
Claudio

[Dean]

Thanks for your reply.

[claudio]

Dear Dr. Yimin Ding

a tutorial on Two-photon absorption is now available here:

https://www.yambo-code.eu/wiki/index.ph ... absorption

best
Claudio

[Dean]

Dear Claudio,
Thanks for your reply.
Best,