High resolution FROG system for the characterization of ps laser pulses

Fuchs, H.; Woll, D.; Ulm, Thorsten; L’huillier, Johannes A.

doi:10.1007/s00340-007-2730-7

Cited by 7 publications

(3 citation statements)

References 13 publications

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“…By using a large, high-resolution spectrometer, a multi-shot FROG has been demonstrated that can measure pulses up to 80 ps in length 14 , and FROG measurements have been made with 20ps temporal range and sub-ps temporal resolution [15][16][17] . A simple version of FROG (called GRENOUILLE) with only three easily aligned optical elements, one of which is a pentagonal SHG crystal, can measure single pulses up to ~20ps long with TBPs of up to ~20.…”

Section: Measuring Beams and Pulsesmentioning

confidence: 99%

Complete measurement of nanosecond laser pulses in time

Bowlan

Trebino

2011

SPIE Proceedings

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It is relatively straightforward to completely measure both long (>10ns) and very short (<100ps) laser pulses in time. But intermediate pulse lengths-that of the most common laser pulsesremain nearly immeasurable and, not coincidentally, correspond to the least stable of all lasers. True, ultrahigh-bandwidth oscilloscopes and streak cameras can now resolve such pulses, but such exotic electronic devices are expensive and fragile and only yield the temporal intensity and not the temporal phase. Here we describe a simple, elegant, accurate, complete, compact, all-optical, entirely passive, and single-shot FROG device that solves the problem. It simultaneously achieves a very large delay range of ~10ns and very high spectral resolution of <1pm. It accomplishes both feats using high-efficiency, high-finesse etalons, the first to tilt the pulse by 89.9, that is, by several meters over a centimeter beam, and another to generate massive angular dispersion for a high-resolution spectrometer. We demonstrate this device for measuring pulses 100ps to several ns long from a fiber-amplified micro-disk laser.Shortly after the development of the first lasers fifty years ago, researchers learned a valuable lesson: the lasers they had labored so hard to develop were not very useful if their beam spatial quality was poor. And it was. Variations in the light intensity and phase from point to point in the beam and also from pulse to pulse made experiments noisy and applications unreliable. Good beam quality-a beam with a simple spatial profile and without such fluctuations-was critical for essentially all experiments and applications. Fortunately, the naked eye can estimate beam quality in visible lasers, and cameras can more quantitatively measure it in nearly all lasers. As a result, researchers were able to improve laser-beam quality considerably. And today a key parameter of any laser's performance is its "space-bandwidth product," roughly the number of bumps in the intensity or phase vs. position (often called M 2 ). Lasers with a poor space-bandwidth product-a value of this parameter much greater than oneare generally of little use.At the same time, using techniques like Q-switching and gain-switching, researchers also began to generate shorter pulses, a few nanoseconds (ns) in length. These lasers provided, not only better temporal resolution, but also much desired higher power. And just as clean, unstructured, and repeatable beams in space were important, equally important for the same reasons were analogously clean, unstructured, and repeatable pulses in time. The pulse timebandwidth product (TBP), roughly, the number of bumps in the intensity or phase vs. time, is as important as its spatial counterpart in experiments and applications.Alas, at the time, even the fastest detectors and oscilloscopes could not resolve such pulses in time. So users of ns pulses had to make do with only rough measures of them. Techniques such as autocorrelation 1-2 emerged, involving splitting the pulse in two, crossing the two resulting pulse ...

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Section: Measuring Beams and Pulsesmentioning

confidence: 99%

Complete measurement of nanosecond laser pulses in time

Bowlan

Trebino

2011

SPIE Proceedings

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“…Researchers have made progress extending ultrafast measurement techniques to the ps regime and to more complex pulses. By using a large, high-resolution spectrometer, a multishot FROG has been demonstrated that can measure pulses up to 80 ps in length [12], and FROG measurements have been made with 20ps temporal range and sub-ps temporal resolution [13,14]. A simple version of FROG (called GRENOUILLE) with only three easily aligned optical elements, one of which is a pentagonal SHG crystal, can measure single pulses up to ~20ps long with TBPs of up to ~20.…”

Section: The Importance Of Measuring Beams and Pulsesmentioning

confidence: 99%

Complete single-shot measurement of arbitrary nanosecond laser pulses in time

Bowlan¹,

Trebino²

2011

Opt. Express

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For essentially all applications, laser pulses must avoid variations in their intensity and phase within a pulse and from pulse to pulse. Currently available devices work very well for both long (>10ns) and short (<100ps) pulses. But intermediate (~ns) pulses remain difficult to measure and, not surprisingly, are the least stable. Here we describe a simple, elegant, complete, all-optical, single-shot device that measures ~ns pulses and that does not require a reference pulse or assumptions about the pulse shape. It simultaneously achieves a very high spectral resolution of <1pm and a very large delay range of ~10ns (several meters of light travel). It accomplishes both goals using high-efficiency, high-finesse etalons: one to generate high angular dispersion for a high-resolution spectrometer, and another to tilt the pulse front by ~89.9° without distorting it in time. Using this device, we completely measure microchip and fiber-amplifier pulses.

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“…So, considering that we want to characterize the output of a fiber amplifier in a single shot, and that it is difficult to find a suitable reference laser to gate it with, FROG seems like the ideal choice. But so far, FROG has never been used for measuring pulses longer than ~100ps, and even this was very difficult [12].…”

Section: Frequency Resolved Optical Gatingmentioning

confidence: 99%