1. Tor Vergata squeezing activity: summary and planning Valeria Sequino

2. Summary Design of a prototype cavity R2>99% @1064 nm R1=92% @1064 nm R2>99.975% @532nm R1=20% @532 nm F=75 @1064 nm FWHM=43 MHz F=3.7 @532 nm FWHM=865 MHz Singly-resonant (@1064) cavity Waist dimension: 62 µm @1064 nm 44 µm @532 nm

3. 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.

4. IR LASER ( Mephisto S200 ) CHARACTERIZATION Quality factor and waist measurement Power stability Laser RIN M 2 =1,08 w 0 = 131,63 µm Stable power of (205.9  0.1) mW reached in roughly 40 minutes

5. 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 performed  loop 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.