Tunnel measurements (March 2022)

Bandwidth in tunnel with both SAGAs is around 19.4 nm FWHM. More bandwidth when only one SAGA is running.

So there is definitely some gain narrowing occurring. Might need a Dazzler to improve this.

Issues in laser room

There were two main issues with the laser spectrum:

• Some modulations on the spectrum that would produce spikes
• Gain narrowing when passing through the amplification stages

Modulations/spikes (fixed)

The modulations originated in the regen (bad alignment) and were then amplified in the several stages.

Fig 1: Spectral measurement after the MPA, showing strong modulation.

Spectra after different stages in the laser room (Zhijiang, Oct 2021): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/42/18.10&pos=2021-10-18T23:59:32

Spectra upstairs/downstairs, in tunnel ~18 nm (Team Laser, Oct 2021): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/42/21.10&pos=2021-10-21T23:24:03

The modulations were seeded by misalignment in the regen, fixed by Andy Mead (Oct 2021): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/42/21.10&pos=2021-10-21T08:13:26

Gain narrowing

Fig 2: Spectral measurements after different amplification stages in the laser room (Henrik, Nov 2021)

Spectra after different stages in the laser room (Henrik, Nov 2021): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/44/03.11&pos=2021-11-03T16:04:48

Spectra after each pass through the MPA (Henrik, Nov 2021): http://physics-elog.slac.stanford.edu/facetelog/show.jsp?dir=/2021/44/05.11&pos=2021-11-05T16:45:30