1. Characterization of short pulses.
A. Yartsev

2. What is good to know about short pulses?
Energy of each pulse
Average power
Spectrum
Spatial distribution
Temporal profile
Satellites
Duration
Shape

3. Energy/Power measurements. from pico-Joule to peta-Watt
Physics of detection
Choice of detector
Linearity
Sensitivity
Spectral response
Response time
Damage

4. Spectral shape What do you need the spectrum for? Sensitivity range.
Calibration of the spectrometer.
Dynamic range.
Optics on the way.
Fibber ”wave guides”.

5. Beam profile Assume Gaussian? Measure real profile.
Measure power through calibrated pinholes
Blade-edge method
Measure real profile.
2-D detector: CCD matrix
1-D array detector
Linearity of response

6. Temporal profile: What for?
Satellites: quality of amplification, quality of measurements
Pulse duration: FWHM
Instrumental response function
Transform-limited pulse
Pulses of random shape

7. Electrical (direct) measurements of pulse duration: not fast enough and (very) expensive.
Photodiode: >10 ps (+fast Oscilloscope)
Streak Camera: 100 fs (?), ~1 ps

8. All-optical methods Time from distance: 1 fs  0.3 m
Math: correlation function
determines F(t) if G() is measured and F’(t) is known.

9. Autocorrelation Interferometric AC Intensity AC Single – shot AC
Both F(t) and F’(t) are replica’s of the same function E(t)exp

10. Interferometric AC F(t) = E(t)exc[it+i(t)]
I1() = |E(t)exc[it+i(t)] +E(t-)exc[i(t- )+i(t-)]|2dt
I2() = |{E(t)exc[it+i(t)] +E(t-)exc[i(t- )+i(t-)]}2|2dt
First order AC: I1(=0)/I1() = 2
Second order AC: I2(=0)/I2() = 8

11. Interferometric AC

12. Interferometric AC

13. Limitions of AC Non-specific: one has assume a particular pulse shape.
Returns only amplitude.

14. Full-field characterization of femtosecond pulses by spectrum and cross-correlation measurements
OPTICS LETTERS / Vol. 24, No. 23 / December 1, 1999
J. W. Nicholson, J. Jasapara, and W. Rudolph
F. G. Omenetto and A. J. Taylor

15. Frequennsy-resolved optical gating FROG
Rev. Sci. Instrum., Vol. 68, No. 9, September 1997
R. Trebino, K. W. DeLong, D. N. Fittinghoff, J. N. Sweetser,

16. FROG Rev. Sci. Instrum., Vol. 68, No. 9, September 1997
R. Trebino, K. W. DeLong, D. N. Fittinghoff, J. N. Sweetser,

17. Single-shot FROG

18. FROG

19. Limitions of FROG
Requirements on set-up: linear detector response, step size, S/N.
Delay-scanning technique.
Measures 2D characteristic – long.
Non-specific: needs a (complicated) retrival to get pulse.
Does not always converge.

20. X-FROG: spectrally-resolved cross-correlation of an unknown pulse with the reference pulse.

21. TADPOLE Rev. Sci. Instrum., Vol. 68, No. 9, September 1997
R. Trebino, K. W. DeLong, D. N. Fittinghoff, J. N. Sweetser,

22. FRPP: pump-probe FROG OPTICS LETTERS / Vol. 27, No. 13 / July 1, 2002
S. Yeremenko, A. Baltuˇska, F. de Haan,
M. S. Pshenichnikov, D. A. Wiersma

23. Self-Referencing Spectral Interferometry for Measuring Ultrashort Optical Pulses SPIDER
IEEE J Quant.Elctr. Vol. 35, No. 4, April 1999
C. Iaconis, I.A. Walmsley

24. SPIDER

25. Advantages of SPIDER No moving parts Direct reconstruction (>1kHz)
Noise immunity
Low sensitivity to detector spectral response
Precision and consistency mesures from data

26. Limitions of SPIDER
Has to be optimised for a particular time-and spectral range.
Requires calibration.
Very sensitive to delay between pulses – sensitive to alignment.

27. After SPIDER: ZAP-SPIDER

28. After SPIDER: SEA-SPIDER
E. M. Kosik and A. S. Radunsky I. A. Walmsley C. Dorrer OPTICS LETTERS Vol. 30, No. 3, 2005

29. After SPIDER: 2DSI OPTICS LETTERS / Vol. 31, No. 13 / July 1, 2006
J. R. Birge, R. Ell, F. X. Kärtner