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Solutions :. 1) Low power Green Laser -> High Finesse cavity -> Feedback to laser PZT to lock 2) High power IR Laser + single pass PPLN SHG -> Low Finesse Cavity, Feedback to laser PZT to lock. Medium and high gain cavity locking was never achieved due to inadequate locking
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Solutions : • 1) Low power Green Laser -> High Finesse cavity -> Feedback to laser PZT to lock • 2) High power IR Laser + single pass PPLN SHG -> Low Finesse Cavity, • Feedback to laser PZT to lock
Medium and high gain cavity locking was never achieved due to inadequate locking • electronics. • Low gain cavity locking was robust, but the power level was much lower than what • we expected. • Room environment was dirty and not suitable for handling cavity mirrors. • Cavity mirror storing and cleaning method wasn’t correct.
The first PCB version of CavLock box has been assembled (Dan Sexton) 16-bit buffered voltage-out DAC module AD5664 successfully integrated to Olimex ADuC7026 micro controller (summer student: Larry Lee) ADuC7020 miniboard has been tested and chosen as a candidate for the next upgrade of CavLock AD5664 ADuC7020
Air flow readjusted so that the room is under positive pressure, 2 HEPA fan filters directly connected to circulated air pipe. • The ceiling is covered with tiles to block the dust. • A softwall frame with the total volume of 600 cf has been assembled around optics table. • 3 HEPA fan filters provide laminar flux to keep the dust particles away from softwall frame.
ROC=0.5m, Φ=10mm, Thickness=5mm Substrate: fused silica Surface RMS roughness < 0.5 Å
Spots are abundant on the mirror surface possibly due to bad packaging.
Smooth lock didn’t last very long. • Oscillatory lock sustains for a long time. • Noise in the locking electronics is the • possible culprit. • Should be able to smooth out the • oscillation. PDR PDH FFBK PDT
For the first time we measured more than 150 Watts of intra cavity power !
GSI-240 is the highest finesse (~12500) cavity we have locked so far ! • Achieved the highest intra cavity power (~150 W) so far ! • Still need to get the peak power by improving the injection optics. • Need to develop good mirror cleaning technique (it is crucial to maximize the power). • Improve electronics and resolve the oscillation in the lock. • Move on to next higher finesse mirrors.
Lock=✔, Solution=✘ 300 W #1 Prometheus Lock=?, Solution=✘ A 700 W 0.1 W #2 Lock=?, Solution=✘ 1.1 kW #3 900 W #1 Lock=✔, Solution=✘ B PPLN 2.1 kW 2 W 0.3 W #2 Lock=?, Solution=✔ Prometheus 3.5 kW #3 Lock=?, Solution=✔