Pulse Characterization | previous | next | feedback |
Optical pulses and regular optical pulse trains can be characterized in various respects:
- The pulse repetition rate is usually measured with a fast photodiode and an electronic spectrum analyzer.
- The pulse duration can be measured with various methods, e.g. with an autocorrelator or a streak camera. Optical sampling techniques can be used when a shorter reference pulse is available.
- The pulse energy may be measured directly or (for pulse trains) calculated from the average power and repetition rate.
- The peak power may be directly measured with a photodiode or calculated from pulse energy, pulse duration and pulse shape.
- The optical center frequency and spectral shape can be obtained with an optical spectrum analyzer.
- The carrier–envelope offset frequency is of special interest in optical metrology, and may be measured with an f−2f interferometer.
- The chirp can be measured e.g. with frequency-resolved optical gating.
- The timing jitter of a pulse train can be measured with various methods.
- The coherence (e.g. of subsequent pulses) can be characterized e.g. with an interferometer.
There are methods of complete pulse characterization [4], which reveal the electric field versus time or the complex spectrum (including spectral shape and spectral phase) of ultrashort pulses. The most prominent techniques for this purpose are FROG (frequency-resolved optical gating [2]) and SPIDER (spectral interferometry for direct electric-field reconstruction [7], → spectral interferometry). The results can be visualized in various ways, e.g. with graphs of time- or frequency-dependent functions, or with spectrograms.
Note that apart from the temporal aspect, there is also the spatial aspect [14]. Both aspects are often approximately separated in the sense that the whole spatio-temporal profile of the electric field of a pulse can be specified as the product of two functions, one depending only on time and the other only on the spatial position. However, a significant coupling of temporal and spatial properties can occur in various situations. For example, pulses from Kerr lens mode-locked lasers often exhibit a time-dependent beam radius, which makes the complete characterization (and modeling) very challenging. Another spatio-temporal aspect is pulse front tilt, which is related to angular dispersion and can, e.g., result from a misaligned pulse compressor.
Bibliography
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| [4] | I. A. Walmsley and V. Wong, “Characterization of the electric field of ultrashort optical pulses”, J. Opt. Soc. Am. B 13 (11), 2453 (1996) |
| [5] | I. D. Jung et al., “High-dynamic-range characterization of ultrashort pulses”, Appl. Phys. B 65, 307 (1997) |
| [6] | R. Trebino et al., “Measuring ultrashort laser pulses in the time–frequency domain using frequency-resolved optical gating”, Rev. Sci. Instrum. 68, 3277 (1997) |
| [7] | C. Iaconis and I. A. Walmsley, “Spectral phase interferometry for direct electric-field reconstruction of ultrashort optical pulses”, Opt. Lett. 23 (10), 792 (1998) |
| [8] | L. Gallmann et al., “Characterization of sub-6-fs optical pulses with spectral phase interferometry for direct electric-field reconstruction”, Opt. Lett. 24 (18), 1314 (1999) |
| [9] | L. Gallmann et al., “Techniques for the characterization of sub-10-fs optical pulses: a comparison”, Appl. Phys. B 70, S67 (2000) |
| [10] | L. Gallmann et al., “Spatially resolved amplitude and phase characterization of femtosecond optical pulses”, Opt. Lett. 26 (2), 96 (2001) |
| [11] | J. W. Nicholson and W. Rudolph, “Noise sensitivity and accuracy of femtosecond pulse retrieval by phase and intensity from correlation and spectrum only (PICASO)”, J. Opt. Soc. Am. B 19 (2), 330 (2002) |
| [12] | T. Hirayama and M. Sheik-Bahae, “Real-time chirp diagnostic for ultrashort laser pulses”, Opt. Lett. 27 (10), 860 (2002) |
| [13] | E. M. Kosik et al., “Interferometric technique for measuring broadband ultrashort pulses at the sampling limit”, Opt. Lett. 30 (3), 326 (2005) |
| [14] | S. Akturk et al., “The general theory of first-order spatio-temporal distortions of Gaussian pulses and beams”, Opt. Express 13 (21), 8642 (2005) |
| [15] | A. S. Wyatt et al., “Sub-10 fs pulse characterization using spatially encoded arrangement for spectral phase interferometry for direct electric field reconstruction”, Opt. Lett. 31 (12), 1914 (2006) |
| [16] | C. Dorrer, “High-speed measurements for optical telecommunication systems”, IEEE J. Sel. Top. Quantum Electron. 12 (4), 843 (2006) |
See also: pulses, spectral phase, carrier–envelope offset, autocorrelators, frequency-resolved optical gating, spectral interferometry
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