LAB-LASER MILANO Pulse shaping Sparc meeting october 4th 2004

OUTLINE Nd:YAG laser state Laser-fiber coupling Pulse “deformation” in BBO crystal Improved shaper design

1- Laser as tool for pulse shaping tests Two weeks ago the laser reached the Project features 100 ps pulse length Amplitude and time stability (few %) 100 MHz operation 2 W output power (20 nJ/pulse)

Now we know in any detail the physics and the technology of each optics inside the laser The subtle connections between the optics and the mode-locked physics of the laser

Laser Nd:YAG

Next on the laser A play for the best trade-off between the pulse length and the pulse energy The implementation of the SESAM technolgy for a real reduction of the pulse length

The coupling in the optical fiber Succesful The ½ km fiber did not arrived in time for this meeting, but ……..

We have solved the listed problems Injection power control Injection optical system Home made beam profiler

Accoppiamento fibra 450 mW (30%)

Spectrum acquisition We have Set the hardware Developed the software We need a phtotomultiplier for the routine operation

Acquisizione spettro

Pulse “deformation” in BBO crossing for harmonic generation We have investigated the effect of the non-linearities in crossing the crystal as function of beam intensity

observations At intensity technically possible the deformation seems negligible/manageable The request on the alignement is just at the limt with BBO crystal The ramp could be found simply rotating the crystal but… a problem with rise time

Possible up-grading of the shaper configurartion From a cross-fertilization of different fields in letterature The hardware is simpler With More software

Vecchio progetto

To get the profile of the output pulse

What Next Shaping of the first harmonic Investigating the non-linearities on the pulse shaping in amplifiers, harmonic generations both in BBO and KDP Test of the pulse shaping with feedback with first harmonic Development of a regenerative amplifier for testing the shaping system with the second harmonic Setting for the third harmonic shaping and the relative tests

This program needs Some investment on hardware

Time schedule We should start hopefully next week the work with the pulse shaping with the first harmonic We belive/hope to write the first experimental article testing a piece of the published theoretical work for the end of the year. We cannot say more for the next-next because we do not know what is in front of us.

Robust photocatodes-SFERA program The experimental result is definitely important QE = 3·10-4 Low field 1 MV/m We are organizing for a test in a rf-gun

THE END

d = modulation amplitude fm = mode locker frequency D f = gain bandwidth