# Ti:sapphire laser does not mode lock at 990nm

**URL:** <https://forum.microlist.org/t/ti-sapphire-laser-does-not-mode-lock-at-990nm/2166>\
**Category:** Hardware\
**Created:** [May 8, 2023, 9:52pm UTC](https://forum.microlist.org/t/ti-sapphire-laser-does-not-mode-lock-at-990nm/2166 "2023-05-08T21:52:25Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Noushin](https://avatars.discourse-cdn.com/v4/letter/n/ecae2f/32.png) [@Noushin](https://forum.microlist.org/u/Noushin)\
**Post date:** [May 8, 2023, 9:52pm UTC](https://forum.microlist.org/t/ti-sapphire-laser-does-not-mode-lock-at-990nm/2166/1 "2023-05-08T21:52:25Z")

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We have a tunable Ti:sapphire laser that does not mode lock at 99nm but it works fine at any other wavelength. I have ruled out the humidity as a cause.  
The representative suggested that this is probably due to drifting away from calibration. Which I am not sure what exactly mean.  
Can someone explain to me why would a laser have a hard time mode locking?

Thanks in advance.