Tor Vergata squeezing activity:summary and planning

Valeria Sequino

Summary• Design of a prototype cavity

R2>99% @1064 nmR1=92% @1064 nm

R2>99.975% @532nmR1=20% @532 nm

F=75 @1064 nm FWHM=43 MHzF=3.7 @532 nm FWHM=865 MHz

Singly-resonant (@1064) cavity

Waist dimension: 62 µm @1064 nm 44 µm @532 nm

• Cavity machining

• Mechanical dry NTC thermistors assembly The two NTC thermistors (in-loop and out-of-loop) are inserted in two grooves drilled in the L shape copper plate. In each groove an indium foil is inserted to have a better thermal contact.

They are fixed by a copper spring and two little screws.

• IR LASER (Mephisto S200) CHARACTERIZATION

Quality factor and waist measurement

Power stability

Laser RIN

M2=1,08

w0 = 131,63 µm

Stable power of (205.90.1) mW reached in roughly 40 minutes

• Temperature control (work in progress…):• In-loop NTC read in a 4-wire configuration• Out-of-loop NTC placed in a Wheatstone bridge• Peltier driven by a DC power supply• OLTF measured• First tests performedloop gain decreased by a factor of 20

Next steps (in collaboration with Napoli-group)• Cavity alignement using a little beam coming from the main laser (same polarization of the pump beam).

• Cavity locking First step: test of locking using the beam used for the alignement. Second step: locking using the Mephisto laser (orthogonal polarization) This laser must be phase locked to the main laser.