Dear Hanbo Jung ,

it looks like a saturation artifact of your detector.

Changing your optics may have increased the photon flux.

You should repeate your measurements with lower (e.g. 1/2 or 1/3) laser power and see what happens ...

Decreasing the detector aperture or a neutral density filter in front of the detector may alternatively help.

Good luck and

best regards

G.M.

Gerhard Martens Thank you very much for your comment. But I think it is not caused by the saturation artifact of our detector. We set the saturation limit was larger than that intensity. Plus if it's saturated, the peak should be flat not decreased like that.

Thanks Hanbo Jung ,

for feed back.

In the photon counting area of x-ray detectors we know the paralyzable behavior of a detector system, which characterized by the decrease of the countrate after reaching the saturation point...

See for example the diagram in:

https://www.radiation-dosimetry.org/what-is-paralyzable-and-non-paralyzable-detector-definition/

Please note, that your peaks have got the same heights of '8000' in 'intensity' ...

Any difference in the peak heights would exclude the saturation issue.

Just to exclude such a behavior of your detector system, I would suggest to decrease the incoming radiation onto the detector and see what is happening with your peak profile...

Best regards

G.M.

Gerhard Martens Georgios N. Arvanitakis Thank you for your comments. I measured it again by decreasing laser power and reduced the slit widths of our system monochromators. But still, that strange double peaks were observed as followed below.

See if you have only 532nm at the laser output. Second harmonic generation lasers often have significant first harmonic residual light at the output. You may need to block the 1064 nm at the output For critical applications.

Dear Leonid Vesselov ,

if present, but how could the 1064nm laser light affect the 690nm regime?

And a change of 532nm output, as you assume due to possible second harmonic generation, will, to my opinion, scale the complete PL peak, but not only the maximum or its center.