Laser / RF Timing ( E ngineering of Femtosecond Timing Systems)
FEMTOSECOND timing!
description
Transcript of FEMTOSECOND timing!
FEMTOSECOND
TIMING!ByMichael Rocco WhalenandCara Perkins
PUMP – PROBE EXPERIMENTS A pump-probe experiment excites an atom
or molecule with a visible laser beam, then probes the object with a hard X-ray. By measuring the timing difference between the two laser pulses, one can rearrange the captured images and create a “movie” of the chemical dynamics.
SIGNAL MIXING
2
=
TESTING FREQUENCY MIXERS FOR POWER SENSITIVITY
CALCULATING SENSITIVITY
SENSITIVITY PERFORMANCE OF THE MIXERS
Mini-Circuits ® Model ZX05-HW-S+
Mini-Circuits ® Model ZFM-4H-S+
Mini-Circuits ® Model ZFM-150
Mixer
Number
Sensitivity
(V/ps)
1 0.023 00
2 0.018 60
3 0.005 96
Average Sensitivity of the Mixers
CAN YOU HEAR ME NOW?
White Noise Spectrum
Pink Noise Spectrum
TESTING THE RF COMPONENTS FOR THEIR NOISE-TO-SENSITIVITY RATIO
Mini-Circuits Splitter Model ZFSC-2-1W+
Anaren Splitter Model 40263
RESOLUTION BANDWIDTH (RBW)
Smaller RBW’s have better resolution. Therefore, harmonics are more apparent. Here, one can see the 60 Hz harmonics coming from nearby power lines.
Larger RBW’s look at a much wider frequency band. The averaging of the frequency measurements eliminates most of the harmonics seen at lower RBW’s.
10 Hz Resolution Bandwidth 10 kHz Resolution Bandwidth
THE SEARCH FOR PINK NOISE
The spectrum analyzer revealed a noise floor that resembled a 1/f curve, but further investigation showed that this was simply the result of averaging the incoming frequencies.
This noise floor was taken at a 100 Hz RBW.
NOISE-TO-SENSITIVITY RATIOS
0 2 4 6 8 10 12 14 16 180.00E+00
5.00E-07
1.00E-06
1.50E-06
2.00E-06
2.50E-06
3.00E-06
Mixer 1, Splitter 1, 100 Hz RBW
5 dBm LO10 dBm LO17 dBm LO20 dBm LO
RF Input
ps/ √
(Hz)
Combination
Noise-to-Sensitivity
Ratio (fs/√(Hz))
LCLS Timescale at 200 kHz RBW
(fs) #1 Mixer, #1 Splitter
6.95E-04 0.311
#1 Mixer, #2 Splitter
7.56E-04 0.338
#2 Mixer, #1 Splitter
9.00E-04 0.402
#2 Mixer, #2 Splitter
7.47E-04 0.334
#3 Mixer, #1 Splitter
1.62E-03 0.724
#3 Mixer, #2 Splitter
1.70E-03 0.760
Average Noise of Mixer and Splitter Combinations
TESTING THE COMPONENTS FOR TEMPERATURE-DEPENDENT PHASE DRIFT
TEMPERATURE AND PHASE DRIFT RESULTS
ComponentPhase Drift
(fs/⁰C)Mini-Circuits Splitter Model ZFSC-2-1W+ 3.780594406Anaren Splitter Model 40263 8.503419973Mini-Circuits Mixer Model ZX05-HW-S+ 26.79407713Mini-Circuits Mixer Model ZFM-4H-S+ 1.694897959Mini-Circuits Mixer Model ZFM-150 6.952019732Aeroflex Phase Shifter Model 980 24.5629370610' Belden Coaxial 50 Ohm Microwave Cable Model 1673A 81.58277672
THANK YOU,
APE (Accelerator
Physics & Engineering)
LAB, for all your assistance in femtosecond measuring!!