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Progress on a LIGO Laser Laboratoryat Trinity University

Dennis Ugolini, Trinity UniversityLSC Meeting, Laser Working Group

March 17, 2004

Laser Working Group, LLO, 3/17/2004

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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

AustinLLO

Laser Working Group, LLO, 3/17/2004

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Physics at Trinity

6 faculty members» 7th 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

Laser Working Group, LLO, 3/17/2004

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Intensity StabilizationStrategies

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.

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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

Laser Working Group, LLO, 3/17/2004

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Current Sensing

0.1 ohm 1% resistorHall effect sensor from

Sypris Test & Instruments

Laser Working Group, LLO, 3/17/2004

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Measured Intensity Noise

Intensity noise of Innolight 500 mW with no power amplifier.

Measurement made with PDA55 photodiode.

Laser Working Group, LLO, 3/17/2004

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Measured Current Noise

Measured with 0.1 ohm resistor.

Shows the same features between 1 and 5 kHz as the intensity noise.

Laser Working Group, LLO, 3/17/2004

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Coherence Plot

Substantial correlation between intensity and current noise from ~300 Hz to ~5 kHz

Laser Working Group, LLO, 3/17/2004

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Innolight “Noise Eater”

“Noise Eater” eliminates current noise for master oscillator!

Laser Working Group, LLO, 3/17/2004

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Future Goals

Acquire power amplifier, repeat current noise measurements

Study beam jitter effects

Take action on communication and feedback with this group