Hello ResearchGate colleagues!
We are encountering the problem with measuring of refractive indices of thin film lithium niobate.
Typically we measure refractive indices by prism coupling method with two light polarisations (TE- and TM-mode) and in two orthogonal directions (parallel and perpendicular to the wafer base slice).
As a result, we have 4 different refractive indices. This is not typical for bulk lithium niobate. It`s looks like we have biaxial crystal (not Uniaxial like bulk LiNbO3).
There are a lot of articles with evidences, that thin film lithium niobate has high tensile stress (more than 150 MPa).
Is it possible that internal stress can change the refractive index by 0.01-0.02?
Do you have any databases where we can find photoelasticity coefficients of LiNbO3?
I will be grateful for any help!
Kırıcılık indisi malzemeye has bir özellik. Meydana gelen olay kimyasal olduğu için kırıcılık indisi değişebilir. Kırıcılık indisi beklenen değerin altında veya ona yakın olur.
Dear Andrei A. Kozlov ,
for photoelastic constants of LiNbO3 please have a look at table IV of
https://univ-angers.hal.science/hal-03420368/document
Is also uploaded to RG:
Article Complete sets of elastic constants and photoelastic coeffici...
Although the constants were taken from LiNbO3 crystals and not from films, they should give a hint on the magnitudes.
See also the table insert in the upper left region of
http://www.mt-berlin.com/frames_ao/descriptions/lnb.htm
and
https://www.photo-lovers.org/pdf/lnb.pdf
as well as
https://www.spiedigitallibrary.org/journals/advanced-photonics/volume-4/issue-03/034003/Advances-in-lithium-niobate-photonics-development-status-and-perspectives/10.1117/1.AP.4.3.034003.full#_=_
This paper is in 'open access'; please download to have access to the constants...
Dear Şükrü Aktaş ,
please focus on what is written in the question; there is no chemical issue; photoelasticity is the topic here...
Best regards
G.M.
Article Photoelastic Properties of Stoichiometric Lithium Niobate fr...
I can also recommend this very recent theoretical article on the topic.
- Badges
- Science topic
- Similar topics
- Papers