1. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 1 Progress on a LIGO Laser Laboratory at Trinity University Dennis Ugolini, Trinity University LSC Meeting, Laser Working Group March 17, 2004

2. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 2 Trinity University  Founded in 1869 in Tehuacana, Texas  Settled permanently in San Antonio in 1952 (~470 miles from LLO)  205 faculty in 26 academic departments, including Department of Engineering  2600 undergraduates, 250 graduate students (mostly accounting and education) San Antonio Austin LLO

3. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 3 Physics at Trinity  6 faculty members »7 th arrives in 2005  Three adjunct/visiting faculty, postdocs  One lab technician  Machine shop, board milling facilities  4-6 majors per year completing thesis projects »Often grow out of junior independent study »Almost half of students publish »About one-third attend graduate school (Princeton, Harvard, UIUC, Rice within last three years)  ~10 electrical engineering majors per year »All complete design projects »Overlap between departments encouraged

4. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 4 Intensity Stabilization Strategies  Fluctuations in current supplied to laser correlate strongly to intensity noise between 200 Hz and 20 kHz (verified at 40m)  Add current sensor to supply, send correction signal to current shunt Current Supply Noise Beam Jitter  Much of low-frequency noise may be due to beam jitter coupling with inhomogeneity in photodiode  Use PZT-actuated steering mirror to measure homogeneity of photodiode  Use quad photodiode as correction signal to steering mirror The Trinity lab will also maintain communication with the ISS/PSL groups, and provide another testbed so that the running of other prototypes is uninterrupted.

5. LIGO-G040075-00-Z 5 Equipment, Facilities, and Personnel Ben Sadler, senior Skyler Saucedo, (headed to UT Austin) junior A total of 400 sq. ft. of lab space is dedicated to the LIGO laser lab Dell Workstation Newport RS1000 5’x8’x8” optical table Innolight Mephisto cw Nd:YAG laser – 500 mW @ 1064 nm

6. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 6 Current Sensing 0.1 ohm 1% resistor Hall effect sensor from Sypris Test & Instruments

7. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 7 Measured Intensity Noise Intensity noise of Innolight 500 mW with no power amplifier. Measurement made with PDA55 photodiode.

8. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 8 Measured Current Noise Measured with 0.1 ohm resistor. Shows the same features between 1 and 5 kHz as the intensity noise.

9. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 9 Coherence Plot Substantial correlation between intensity and current noise from ~300 Hz to ~5 kHz

10. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 10 Innolight “Noise Eater” “Noise Eater” eliminates current noise for master oscillator!

11. LIGO-G040075-00-Z Laser Working Group, LLO, 3/17/2004 11 Future Goals  Acquire power amplifier, repeat current noise measurements  Study beam jitter effects  Take action on communication and feedback with this group