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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 17, Iss. 26 — Dec. 21, 2009
  • pp: 23894–23902
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Optimization of few-cycle pulse generation: Spatial size, mode quality and focal volume effects in filamentation based pulse compression

Adam Roberts, Niranjan Shivaram, Lei Xu, and Arvinder Sandhu  »View Author Affiliations


Optics Express, Vol. 17, Issue 26, pp. 23894-23902 (2009)
http://dx.doi.org/10.1364/OE.17.023894


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Abstract

We demonstrate the key role played by the spatial characteristics and focusing conditions of a femtosecond multi-cycle laser pulse in optimization of filament output for the purpose of obtaining compressed light pulses in the few-cycle regime. We find that for a given beam profile and focal parameters, driving the filament with energy above a certain limiting value can negatively impact pulse compression. However, for a given energy, a smaller and cleaner input beam mode obtained by using a hard aperture can substantially improve the pulse compression ability. In addition, we show that a larger focal volume can assist in creation of a shorter output pulse.

© 2009 OSA

1. Introduction

High intensity laser filamentation [1

1. A. Couairon and A. Mysyrowicz, “Femtosecond filamentation in transparent media,” Physics Reports-Review Section of Physics Letters 441, 47–189 (2007).

] plays a critical role in many ultrafast physics laboratories. Short pulse filamentation is employed for the generation of many useful photon sources such as white light supercontinuum [2

2. S. A. Trushin, S. Panja, K. Kosma, W. E. Schmid, and W. Fuß, “Supercontinuum extending from > 1000 to 250 nm, generated by focusing ten-fs laser pulses at 805 nm into Ar,” Appl. Phys. B 80(4-5), 399–403 (2005). [CrossRef]

], Ultraviolet/harmonic emission [3

3. F. Theberge, Q. Luo, W. Liu, S. A. Hosseini, M. Sharifi, and S. L. Chin, “Long-range third-harmonic generation in air using ultrashort intense laser pulses,” Appl. Phys. Lett. 87(8), 081108 (2005). [CrossRef]

, 4

4. M. Kolesik, E. M. Wright, A. Becker, and J. V. Moloney, “Simulation of third-harmonic and supercontinuum generation for femtosecond pulses in air,” Appl. Phys. B 85(4), 531–538 (2006). [CrossRef]

], terahertz radiation [5

5. S. Tzortzakis, G. Méchain, G. Patalano, Y. B. André, B. Prade, M. Franco, A. Mysyrowicz, J. M. Munier, M. Gheudin, G. Beaudin, and P. Encrenaz, “Coherent subterahertz radiation from femtosecond infrared filaments in air,” Opt. Lett. 27(21), 1944–1946 (2002). [CrossRef] [PubMed]

], and offers unique applications in areas such as micromachining and atmospheric detection/ranging [6

6. S. L. Chin, S. A. Hosseini, W. Liu, Q. Luo, F. Theberge, N. Akozbek, A. Becker, V. P. Kandidov, O. G. Kosareva, and H. Schroeder, “The propagation of powerful femtosecond laser pulses in optical media: physics, applications, and new challenges,” Can. J. Phys. 83(9), 863–905 (2005). [CrossRef]

]. In particular, from the view point of ultrafast laser sources, filamentation provides a simple technique for generation of extra bandwidth required to reduce the 30-40 femtosecond output of a commercial near-IR Ti:Sapphire laser amplifier to the sub-10 femtosecond or few-cycle regime. The short few-cycle laser pulses thus generated offer high temporal resolution and applicability of carrier-envelope-phase control techniques [7

7. T. Brabec and F. Krausz, “Intense few-cycle laser fields: Frontiers of nonlinear optics,” Rev. Mod. Phys. 72(2), 545–591 (2000). [CrossRef]

], providing new insights into the ultrafast electronic and nuclear processes occurring in gas and condensed phase matter. Moreover, few-cycle light pulses are crucial for the generation of the isolated and controlled attosecond light waveforms in the XUV regime, thereby opening the doors for real-time probing of fast electron dynamics associated with excited-state atomic and molecular processes [8

8. F. Krausz and M. Ivanov, “Attosecond physics,” Rev. Mod. Phys. 81(1), 163–234 (2009). [CrossRef]

14

14. A. S. Sandhu, E. Gagnon, R. Santra, V. Sharma, W. Li, P. Ho, P. Ranitovic, C. L. Cocke, M. M. Murnane, and H. C. Kapteyn, “Observing the creation of electronic feshbach resonances in soft x-ray-induced O2 dissociation,” Science 322(5904), 1081–1085 (2008). [CrossRef] [PubMed]

]. Currently, the filamentation induced bandwidth enhancement followed by compression with external optical elements has been used to generate pulses below 10 fs [15

15. C. P. Hauri, W. Kornelis, F. W. Helbing, A. Heinrich, A. Couairon, A. Mysyrowicz, J. Biegert, and U. Keller, “Generation of intense, carrier-envelope phase-locked few-cycle laser pulses through filamentation,” Appl. Phys. B 79(6), 673–677 (2004). [CrossRef]

21

21. J. Y. Park, J. H. Lee, and C. H. Nam, “Laser chirp effect on femtosecond laser filamentation generated for pulse compression,” Opt. Express 16(7), 4465–4470 (2008). [CrossRef] [PubMed]

] and in some cases as short as 4.9 fs [22

22. A. Zaïr, A. Guandalini, F. Schapper, M. Holler, J. Biegert, L. Gallmann, U. Keller, A. Couairon, M. Franco, and A. Mysyrowicz, “Spatio-temporal characterization of few-cycle pulses obtained by filamentation,” Opt. Express 15(9), 5394–5404 (2007). [CrossRef] [PubMed]

].

Recently, there has been significant emphasis on the methods to control laser pulse filamentation due to its utility in creation of few-cycle pulses that are crucial for advance in attosecond science. Recent innovations have included using liquid crystals to control the phase across the beam [23

23. D. Walter, S. Eyring, J. Lohbreier, R. Spitzenpfeil, and C. Spielmann, “Spatial optimization of filaments,” Appl. Phys. B 88(2), 175–178 (2007). [CrossRef]

], which allowed a genetic algorithm to optimize the spatial profile of the output from the filament. Circular phase masks have been used to enhance the bandwidth generated in a filament while also improving the pointing stability [24

24. T. Pfeifer, L. Gallmann, M. J. Abel, D. M. Neumark, and S. R. Leone, “Circular phase mask for control and stabilization of single optical filaments,” Opt. Lett. 31(15), 2326–2328 (2006). [CrossRef] [PubMed]

]. Others methods for controlling the filamentation and short pulse generation include changing the gas pressure [16

16. C. P. Hauri, A. Guandalini, P. Eckle, W. Kornelis, J. Biegert, and U. Keller, “Generation of intense few-cycle laser pulses through filamentation - parameter dependence,” Opt. Express 13(19), 7541–7547 (2005). [CrossRef] [PubMed]

], group velocity dispersion, using a pressure gradient [25

25. A. Couairon, M. Franco, A. Mysyrowicz, J. Biegert, and U. Keller, “Pulse self-compression to the single-cycle limit by filamentation in a gas with a pressure gradient,” Opt. Lett. 30(19), 2657–2659 (2005). [CrossRef] [PubMed]

], or using a soft aperture [20

20. X. W. Chen, X. F. Li, J. Liu, P. F. Wei, X. C. Ge, R. X. Li, and Z. Z. Xu, “Generation of 5 fs, 0.7 mJ pulses at 1 kHz through cascade filamentation,” Opt. Lett. 32(16), 2402–2404 (2007). [CrossRef] [PubMed]

].

It is generally accepted that apart from usual variables such as input energy and gas pressure, the spatial parameters of the input laser beam play an important role in the filamentation process [1

1. A. Couairon and A. Mysyrowicz, “Femtosecond filamentation in transparent media,” Physics Reports-Review Section of Physics Letters 441, 47–189 (2007).

, 16

16. C. P. Hauri, A. Guandalini, P. Eckle, W. Kornelis, J. Biegert, and U. Keller, “Generation of intense few-cycle laser pulses through filamentation - parameter dependence,” Opt. Express 13(19), 7541–7547 (2005). [CrossRef] [PubMed]

, 26

26. A. Couairon, M. Franco, G. Mechain, T. Olivier, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures: Part I: Theory and numerical simulations,” Opt. Commun. 259(1), 265–273 (2006). [CrossRef]

, 27

27. G. Mechain, T. Olivier, M. Franco, A. Couairon, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures. Part 11: Laboratory experiments,” Opt. Commun. 261(2), 322–326 (2006). [CrossRef]

]. For example, in a study of propagation of intense laser pulses in atmosphere, the stability of backscattered fluorescence signal has been found to depend upon beam diameter used [28

28. Q. Luo, S. A. Hosseini, W. Liu, J. F. Gravel, O. G. Kosareva, N. A. Panov, N. Akozbek, V. P. Kandidov, G. Roy, and S. L. Chin, “Effect of beam diameter on the propagation of intense femtosecond laser pulses,” Appl. Phys. B 80, 35–38 (2005). [CrossRef]

]. Thus, one should expect the spatial size, profile and focusing conditions of the input laser beam to strongly influence the dispersion characteristics and the temporal compressibility of the filament output. Some recent studies discuss the effect of spatial profile on temporal self-compression in a filament [29

29. S. Skupin, G. Stibenz, L. Bergé, F. Lederer, T. Sokollik, M. Schnürer, N. Zhavoronkov, and G. Steinmeyer, “Self-compression by femtosecond pulse filamentation: experiments versus numerical simulations,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 74(5 Pt 2), 056604 (2006). [CrossRef] [PubMed]

, 30

30. N. Zhavoronkov, “Fine control of self-compression dynamics in a femtosecond filament,” J. Opt. A, Pure Appl. Opt. 11(12), 125201 (2009). [CrossRef]

]. However, many typical few-cycle pulse generation setups employ the post-filament external dispersion compression scheme, as is the case in our study. In this regime, some authors have noted in passing that a specific beam size or focusing lens led to better output pulse duration [21

21. J. Y. Park, J. H. Lee, and C. H. Nam, “Laser chirp effect on femtosecond laser filamentation generated for pulse compression,” Opt. Express 16(7), 4465–4470 (2008). [CrossRef] [PubMed]

]. However, these studies do not delve any further into this matter as their objective is different. In fact, we not aware of any comprehensive study that explores the role of various spatial parameters on few-cycle pulse generation based upon filamentation and external compression. In this paper, we perform a detailed experimental study of degree of pulse compression that can be achieved through modification of the laser beam size, profile and focusing parameters vis-à-vis the input pulse energy and gas pressure variation. Our effort is also unique in the sense that we systematically isolate the effect of each of the coupled variables through careful experimentation. Below, we present experimental results quantifying the role of pulse energy, beam diameter, M-squared (M2) value, and f-number (f/#) of the input beam on the output pulse duration obtained from a single filamentation setup that incorporates external dispersion compensation. This understanding is important to improve the efficiency and energy economy of filamentation setups that are typically used in few-cycle light pulse generation.

2. Experimental procedure

The experimental set up is shown in Fig. 1(a)
Fig. 1 (a) Experimental set up. (b) The compressed pulse duration as a function of input pulse energy and gas pressure. The pulse energy is varied using an aperture. The minimum pulse duration obtained is 9fs.
. The laser amplifier generates 40fs pulses up to 2.5 mJ pulse energy at 1 kHz repetition rate. We focus the laser pulses with a 1m focal length spherical mirror in a slightly off-axis configuration into a long (~1.4 m) argon filled gas cell with variable pressure. The windows of the cell are chosen to be very thin (0.1 mm) to prevent any non-linear effects. The high intensity pulse propagating through Ar cell leads to formation of a filament. The bandwidth stretched output of the filament is collimated with another spherical mirror on to a chirped mirror pair (GVD ~-60fs2 per mirror bounce) which recompresses the pulse in three passes. The final pulse duration is measured using a Frequency Resolved Optical Gating (FROG) set-up under different energy, spatial size, spatial profile, gas pressure, and focal length conditions. In these studies, we make a conscious effort to isolate the effect of each input beam parameter by systematically removing the contributions from other variables. The spectrum marginal of the FROG trace is used as relative measure of the bandwidth generated under different input conditions. The symmetric shape of the FROG spectrum marginal provides a consistent 1/e2 width measurement as compared to the raw spectrum of the filament output.

3. Results and discussion

In order to scan the parameter space for short pulse generation, we begin by varying the gas pressure and the input pulse energy while recording the pulse duration at each setting. In this case, a hard aperture was used to control the input pulse energy. Figure 1(b) shows the results of this wide parameter scan. We observe a valley region, between pulse energy 0.85 mJ ± 0.25mJ. This region represents a stable optimal parameter regime, where the pulse duration is very short and approaches the few-cycle regime. In this regime, the pulse experiences the best compression for a given chirped mirror configuration. Further, we note that the use of a different number of passes through the chirped mirror pair still leads to the same general characteristic behavior with another optimal valley region, however, the minimum pulse duration obtained is higher. This implies that departure from valley to peak regions at higher pulse energies in Fig. 1(b) is not due to lack of negative dispersion from chirped mirror pair, but rather it is due to non-availability of bandwidth or the non-linear dispersion in the filament spectrum. We discuss this aspect later in the paper with additional data supporting this observation.

An important feature seen in Fig. 1(b) is that the pulse duration experiences a sharp rise when we increase the energy above 1mJ. However, in the data under consideration in Fig. 1(b), the variation in the pulse energy is obtained while controlling the spatial size of the beam with a hard aperture. In order to understand the short pulse generation and the sharp cut-off in the compressibility at higher pulse energy we obviously need to individually address the energy and spatial size dependence.

3.1 Input pulse energy dependence

To investigate the role of the input pulse energy, we use a half-wave plate and polarizer to control the intensity while maintaining the same aperture size and beam profile. In Fig. 2
Fig. 2 The output pulse duration (left y-axis) and bandwidth (right y-axis) as a function of the input pulse energy. Pulse energy varied using a half-wave plate/polarizer pair and the spatial profile is kept constant. Two combinations of gas pressure and beam area are shown. The (blue) circles are for the 1000 torr, 89 mm2 case, and the (gray) triangles are the 673 torr, 125 mm2 case. Solid lines are guide to the eye. Plotted along right y-axis is the bandwidth data for 1000 torr, 89mm2 case in (red) squares. Bandwidth is determined from 1/e2 width of spectrum marginal of FROG trace.
, we vary the pulse energy from 0.2mJ to 1.8mJ and plot the pulse duration strictly as a function of the input pulse energy alone. Figure 2 also shows a region (valley) of minimal pulse duration (optimal pulse compression) as observed in Fig. 1(b). The pulse duration measurements in Fig. 2 are done for two different combinations of gas pressure and circular aperture size (or beam area), i.e. P = 1000 torr, beam area = 89mm2 and P = 673 torr, beam area = 125 mm2.

On the right y-axis of Fig. 2, we plot the bandwidth measure obtained from spectrum marginal of FROG trace for the data corresponding to 1000 torr gas pressure and 89 mm2 beam area. This data set illustrates the relative amount of bandwidth that is available for pulse compression under varying pulse energies of driving laser beam and thus helps in the clarification of underlying mechanisms.

As seen in Fig. 2, at low energies we get temporally long pulses, which are easily explained due to lack of filamentation at low input energies. This is also borne out by the lack of bandwidth availability at low energies in Fig. 2. However, there is still significant dispersion due to neutral Ar gas in the cell, which is then compensated by negative dispersion mirrors, so the output pulse is roughly the same length as the pulse directly out of the amplifier. On the high energy side, the output pulse duration also gets longer. Based on this information alone, one could argue that longer pulse duration could be due to lack of dispersion compensation of the additional bandwidth generated at high energies. However, we observe that maximum amount of bandwidth is generated in the optimal pulse compression region and there is no extra bandwidth obtained at higher energies. The lack of additional bandwidth at high pulse energies can be explained in terms of saturation mechanisms such as intensity clamping [31

31. A. Couairon, “Dynamics of femtosecond filamentation from saturation of self-focusing laser pulses,” Phys. Rev. A 68(1), 015801 (2003). [CrossRef]

]. As there is no additional bandwidth at high pulse energies and yet the output pulse duration lengthened, this implies that by driving the filament with too much energy makes the bandwidth less compressible. For instance, the higher energies could add a nonlinear phase to the spectrum that would not be compressible by the use of standard chirped mirrors.

3.2 Beam size dependence

In order to investigate the role of input beam size in generation of few-cycle pulses observed in the optimal valley region of Fig. 1(b), we perform the study at fixed input energy (again using the half-wave plate and polarizer), but vary the aperture diameter and hence the area of the input beam. The results of this experiment are presented in Fig. 3
Fig. 3 Pulse duration (left axis) and bandwidth (right axis) correlation observed by varying the aperture size while maintaining a fixed input energy. Output pulse duration for 0.8 mJ, 1000 torr case is shown by (blue) circles plot, while the the (gray) triangles represent 1 mJ, 700 torr case. Observed output bandwidth on right axis is shown by the (red) squares plot for 0.8mJ, 1000 torr case.
. We choose a fixed energy values that corresponds to the best compression cases as observed in Fig. 2 namely 0.8mJ at 1000 torr and 1mJ at 700 torr. It is evident from Fig. 3 that even at the optimal value of input energy; the pulse compression can be substantially improved by changing the beam (aperture) size. This effect is observable even without making any FROG measurements. When varying the aperture, there is a point when the extra colors become visible even to an unassisted eye. The filament becomes much brighter in the visible region when the aperture is slowly closed. The relative bandwidth plot shown in Fig. 3 serves to quantify the increase in bandwidth with decreasing aperture size (at fixed input energy and pressure 0.8mJ, 1000 torr). As before, this data also implies that we are able to compress pulses to a shorter duration by increasing the bandwidth without the need for any adjustment to dispersion compensation scheme in the chirped mirror pair.

While the measurement shown in Fig. 3 points to the importance of beam size in short pulse generation, but still do not differentiate between the individual roles of cleanliness of the beam profile and beam focusing conditions, as both are affected by variation of the aperture size. When changing the aperture size, beam is being spatially modified and we could be selecting a better central portion which creates an ideal filament for pulse compression. On the same token, having a smaller beam diameter also leads to a larger focal volume.

3.3 Beam profile (M2) dependence

We first study the variation of the beam quality as we change the aperture size. In Fig. 4
Fig. 4 (Left axis) Pulse duration data shown by (blue) circles, as a function of the area of the aperture. (Right axis) Normalized M2/M0 2 variation shown by (green) squares, as a function of the area of the aperture. These data sets are obtained under fixed input energy conditions (0.8mJ, 1000 torr). The M2 is computed in the linear regime in air and normalized by M0 2 corresponding to the fully open beam.
we show the pulse duration as a function of aperture size. In the same plot, along the right y-axis, we plot the relative M-squared (M2/M0 2) values such that maximum value (M0 2) is normalized to unity. The beam profiling measurements were done with a somewhat crude set up that had substantial background noise and damage spots on imaging sensor. While, accurate determination of absolute M-square was not possible with our setup, the normalized data presented in Fig. 4 still allows us to establish the general trend in variation of M-square values as a function of aperture size. We observe that there is a strong correlation between the normalized M2/M0 2 values of the beam and the output pulse duration indicating that the beam profile cleanliness is an important factor in obtaining short few-cycle pulses through filamentation process. For example, in many situations, choosing a laser amplifier with higher pulse energy to generate higher energy filamentation output may not necessarily lead to few-cycle pulses, unless the beam profile considerations are carefully weighed in.

3.5 Focal volume dependence

As mentioned earlier, the aperturing of laser beam not only modifies the quality of beam profile but also leads to changes in the focal volume. In order to isolate the effect of focal volume of beam, we need to study it without varying the aperture size and the beam profile. To do so, we use a telephoto lens pair of +200mm and −150mm and varied the separation between the two to have a variable focal length. Using different focal lengths to focus into the argon allows us to change the beam's focal volume while keeping the same M-squared value for each case. For simplicity, we define the focal volume as the Gaussian beam waist area multiplied by the Rayleigh range. The energy and pressure conditions are same as in the earlier case i.e. 0.8mJ and 1000 torr.

We compare the focal volume dependence arising from the variation of the aperture size (which includes both spatial profile modification and focal spot-size changes) and the variation of the focal length (which does not change spatial profile), by plotting the pulse duration in both cases as a function of calculated focal volume (Fig. 5
Fig. 5 Comparing the pulse compression vs focal volume for two cases - modification the diameter of the beam (green squares) and modification of the focal length of the lenses used to focus the beam (red diamonds). The different focal lengths obtained using a variable separation + 200m and −150mm lens pair are shown along top x-axis for the (red) diamonds data set.
). Up to 15 mm3 there seems to be a general agreement between the two cases - as the focal volume increases the pulse becomes shorter. At very large focal volume (or focal length of our lens pair) we reach a point after which the power in the focal volume becomes too low for optimal filamentation and hence the pulse duration starts increasing back again.

The focal length numbers that we employed using the lens pair varied from 1.5m to 2.5m as shown on the top-x-axis (applicable only for red diamond data set). There were physical limitations over the range of focal lengths that we could use. On the short focal length side, the limit is that the back focal distance of the lens pair must be longer than half of Argon cell length. On the long focal length side, we are limited by the fact that we were not varying the focal length of the re-collimating mirror. This means that as the beam gets smaller due to transverse magnification, the mirrors in the system will have increasingly high flux incident from the filament. We stopped at 2.5m focal length to avoid damage to the mirrors downstream of the filament. The 1 meter focal length (top x-axis) data point was taken using the spherical mirror to show that using the lenses did not significantly affect our other input beam parameters

Confining ourselves to reasonable tight focal volumes (< 20mm3), it can be said that a loosely focused beam creates an optimal filament that is better suited for pulse compression. One can further reason that having a loose focus leads to increased tendency for beam to refocus and allows the pulse to interact with the filament core for a longer period. In any case, we see that without modifying the M2 value we can still optimize our compression by generating a larger focal volume.

4. Conclusions

To summarize, we have performed a detailed investigation of the effects of pulse energy, beam size, spatial profile and the focusing conditions of the high intensity input laser pulse on the generation of short, few-cycle pulses in a filamentation based scheme. Using a hard aperture to limit the input energy, we found that for a given pressure there is a broad optimal energy regime for creation of a short sub-10fs output pulse. Driving the filament above this energy does not create any additional bandwidth that can be compressed. However, under constant input energy conditions, using an aperture to make the beam diameter smaller did result in more bandwidth which could be compressed to make a shorter output pulse. Further, by measuring the relative M-square values at different aperture sizes, we find that cleanliness of the beam profile is strongly correlated with the shortest pulse duration that be obtained in this method. Finally, the focal volume is also shown to play a significant role in short pulse generation and loose focusing is found to lead to better filamentation and shorter output pulses. These findings serve to elucidate general pointers for economical use of limited energy of amplified laser pulses to generate intense few-cycles pulses through optimal combination of input pulse energy, beam profile cleanliness and focal volume parameters.

We thank M. Kolesik for useful discussions. We thankfully acknowledge Science Foundation Arizona for the graduate fellowship that supported one of the authors (A.R.).

References and links

1.

A. Couairon and A. Mysyrowicz, “Femtosecond filamentation in transparent media,” Physics Reports-Review Section of Physics Letters 441, 47–189 (2007).

2.

S. A. Trushin, S. Panja, K. Kosma, W. E. Schmid, and W. Fuß, “Supercontinuum extending from > 1000 to 250 nm, generated by focusing ten-fs laser pulses at 805 nm into Ar,” Appl. Phys. B 80(4-5), 399–403 (2005). [CrossRef]

3.

F. Theberge, Q. Luo, W. Liu, S. A. Hosseini, M. Sharifi, and S. L. Chin, “Long-range third-harmonic generation in air using ultrashort intense laser pulses,” Appl. Phys. Lett. 87(8), 081108 (2005). [CrossRef]

4.

M. Kolesik, E. M. Wright, A. Becker, and J. V. Moloney, “Simulation of third-harmonic and supercontinuum generation for femtosecond pulses in air,” Appl. Phys. B 85(4), 531–538 (2006). [CrossRef]

5.

S. Tzortzakis, G. Méchain, G. Patalano, Y. B. André, B. Prade, M. Franco, A. Mysyrowicz, J. M. Munier, M. Gheudin, G. Beaudin, and P. Encrenaz, “Coherent subterahertz radiation from femtosecond infrared filaments in air,” Opt. Lett. 27(21), 1944–1946 (2002). [CrossRef] [PubMed]

6.

S. L. Chin, S. A. Hosseini, W. Liu, Q. Luo, F. Theberge, N. Akozbek, A. Becker, V. P. Kandidov, O. G. Kosareva, and H. Schroeder, “The propagation of powerful femtosecond laser pulses in optical media: physics, applications, and new challenges,” Can. J. Phys. 83(9), 863–905 (2005). [CrossRef]

7.

T. Brabec and F. Krausz, “Intense few-cycle laser fields: Frontiers of nonlinear optics,” Rev. Mod. Phys. 72(2), 545–591 (2000). [CrossRef]

8.

F. Krausz and M. Ivanov, “Attosecond physics,” Rev. Mod. Phys. 81(1), 163–234 (2009). [CrossRef]

9.

A. Couairon, H. S. Chakraborty, and M. B. Gaarde, “From single-cycle self-compressed filaments to isolated attosecond pulses in noble gases,” Phys. Rev. A 77(5), 053814 (2008). [CrossRef]

10.

H. S. Chakraborty, M. B. Gaarde, and A. Couairon, “Single attosecond pulses from high harmonics driven by self-compressed filaments,” Opt. Lett. 31(24), 3662–3664 (2006). [CrossRef] [PubMed]

11.

M. B. Gaarde and A. Couairon, “Intensity Spikes in Laser Filamentation: Diagnostics and Application,” Phys. Rev. Lett. 103(4), 043901 (2009). [CrossRef] [PubMed]

12.

A. S. Sandhu, E. Gagnon, A. Paul, I. Thomann, A. Lytle, T. Keep, M. M. Murnane, H. C. Kapteyn, and I. P. Christov, “Generation of sub-optical-cycle, carrier-envelope-phase - insensitive, extreme-uv pulses via nonlinear stabilization in a waveguide,” Phys. Rev. A 74(6), 061803 (2006). [CrossRef]

13.

E. Gagnon, P. Ranitovic, X. M. Tong, C. L. Cocke, M. M. Murnane, H. C. Kapteyn, and A. S. Sandhu, “Soft X-ray-driven femtosecond molecular dynamics,” Science 317(5843), 1374–1378 (2007). [CrossRef] [PubMed]

14.

A. S. Sandhu, E. Gagnon, R. Santra, V. Sharma, W. Li, P. Ho, P. Ranitovic, C. L. Cocke, M. M. Murnane, and H. C. Kapteyn, “Observing the creation of electronic feshbach resonances in soft x-ray-induced O2 dissociation,” Science 322(5904), 1081–1085 (2008). [CrossRef] [PubMed]

15.

C. P. Hauri, W. Kornelis, F. W. Helbing, A. Heinrich, A. Couairon, A. Mysyrowicz, J. Biegert, and U. Keller, “Generation of intense, carrier-envelope phase-locked few-cycle laser pulses through filamentation,” Appl. Phys. B 79(6), 673–677 (2004). [CrossRef]

16.

C. P. Hauri, A. Guandalini, P. Eckle, W. Kornelis, J. Biegert, and U. Keller, “Generation of intense few-cycle laser pulses through filamentation - parameter dependence,” Opt. Express 13(19), 7541–7547 (2005). [CrossRef] [PubMed]

17.

A. Couairon, J. Biegert, C. P. Hauri, W. Kornelis, F. W. Helbing, U. Keller, and A. Mysyrowicz, “Self-compression of ultra-short laser pulses down to one optical cycle by filamentation,” J. Mod. Opt. 53(1-2), 75–85 (2006). [CrossRef]

18.

G. Stibenz, N. Zhavoronkov, and G. Steinmeyer, “Self-compression of millijoule pulses to 7.8 fs duration in a white-light filament,” Opt. Lett. 31(2), 274–276 (2006). [CrossRef] [PubMed]

19.

A. Guandalini, P. Eckle, M. Anscombe, P. Schlup, J. Biegert, and U. Keller, “5.1 fs pulses generated by filamentation and carrier envelope phase stability analysis,” J. Phys. At. Mol. Opt. Phys. 39(13), S257–S264 (2006). [CrossRef]

20.

X. W. Chen, X. F. Li, J. Liu, P. F. Wei, X. C. Ge, R. X. Li, and Z. Z. Xu, “Generation of 5 fs, 0.7 mJ pulses at 1 kHz through cascade filamentation,” Opt. Lett. 32(16), 2402–2404 (2007). [CrossRef] [PubMed]

21.

J. Y. Park, J. H. Lee, and C. H. Nam, “Laser chirp effect on femtosecond laser filamentation generated for pulse compression,” Opt. Express 16(7), 4465–4470 (2008). [CrossRef] [PubMed]

22.

A. Zaïr, A. Guandalini, F. Schapper, M. Holler, J. Biegert, L. Gallmann, U. Keller, A. Couairon, M. Franco, and A. Mysyrowicz, “Spatio-temporal characterization of few-cycle pulses obtained by filamentation,” Opt. Express 15(9), 5394–5404 (2007). [CrossRef] [PubMed]

23.

D. Walter, S. Eyring, J. Lohbreier, R. Spitzenpfeil, and C. Spielmann, “Spatial optimization of filaments,” Appl. Phys. B 88(2), 175–178 (2007). [CrossRef]

24.

T. Pfeifer, L. Gallmann, M. J. Abel, D. M. Neumark, and S. R. Leone, “Circular phase mask for control and stabilization of single optical filaments,” Opt. Lett. 31(15), 2326–2328 (2006). [CrossRef] [PubMed]

25.

A. Couairon, M. Franco, A. Mysyrowicz, J. Biegert, and U. Keller, “Pulse self-compression to the single-cycle limit by filamentation in a gas with a pressure gradient,” Opt. Lett. 30(19), 2657–2659 (2005). [CrossRef] [PubMed]

26.

A. Couairon, M. Franco, G. Mechain, T. Olivier, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures: Part I: Theory and numerical simulations,” Opt. Commun. 259(1), 265–273 (2006). [CrossRef]

27.

G. Mechain, T. Olivier, M. Franco, A. Couairon, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures. Part 11: Laboratory experiments,” Opt. Commun. 261(2), 322–326 (2006). [CrossRef]

28.

Q. Luo, S. A. Hosseini, W. Liu, J. F. Gravel, O. G. Kosareva, N. A. Panov, N. Akozbek, V. P. Kandidov, G. Roy, and S. L. Chin, “Effect of beam diameter on the propagation of intense femtosecond laser pulses,” Appl. Phys. B 80, 35–38 (2005). [CrossRef]

29.

S. Skupin, G. Stibenz, L. Bergé, F. Lederer, T. Sokollik, M. Schnürer, N. Zhavoronkov, and G. Steinmeyer, “Self-compression by femtosecond pulse filamentation: experiments versus numerical simulations,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 74(5 Pt 2), 056604 (2006). [CrossRef] [PubMed]

30.

N. Zhavoronkov, “Fine control of self-compression dynamics in a femtosecond filament,” J. Opt. A, Pure Appl. Opt. 11(12), 125201 (2009). [CrossRef]

31.

A. Couairon, “Dynamics of femtosecond filamentation from saturation of self-focusing laser pulses,” Phys. Rev. A 68(1), 015801 (2003). [CrossRef]

OCIS Codes
(320.0320) Ultrafast optics : Ultrafast optics
(320.5520) Ultrafast optics : Pulse compression

ToC Category:
Ultrafast Optics

History
Original Manuscript: October 21, 2009
Revised Manuscript: December 7, 2009
Manuscript Accepted: December 8, 2009
Published: December 15, 2009

Citation
Adam Roberts, Niranjan Shivaram, Lei Xu, and Arvinder Sandhu, "Optimization of few-cycle pulse generation: Spatial size, mode quality and focal volume effects in filamentation based pulse compression," Opt. Express 17, 23894-23902 (2009)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-26-23894


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References

  1. A. Couairon and A. Mysyrowicz, “Femtosecond filamentation in transparent media,” Physics Reports-Review Section of Physics Letters 441, 47–189 (2007).
  2. S. A. Trushin, S. Panja, K. Kosma, W. E. Schmid, and W. Fuß, “Supercontinuum extending from > 1000 to 250 nm, generated by focusing ten-fs laser pulses at 805 nm into Ar,” Appl. Phys. B 80(4-5), 399–403 (2005). [CrossRef]
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  10. H. S. Chakraborty, M. B. Gaarde, and A. Couairon, “Single attosecond pulses from high harmonics driven by self-compressed filaments,” Opt. Lett. 31(24), 3662–3664 (2006). [CrossRef] [PubMed]
  11. M. B. Gaarde and A. Couairon, “Intensity Spikes in Laser Filamentation: Diagnostics and Application,” Phys. Rev. Lett. 103(4), 043901 (2009). [CrossRef] [PubMed]
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  13. E. Gagnon, P. Ranitovic, X. M. Tong, C. L. Cocke, M. M. Murnane, H. C. Kapteyn, and A. S. Sandhu, “Soft X-ray-driven femtosecond molecular dynamics,” Science 317(5843), 1374–1378 (2007). [CrossRef] [PubMed]
  14. A. S. Sandhu, E. Gagnon, R. Santra, V. Sharma, W. Li, P. Ho, P. Ranitovic, C. L. Cocke, M. M. Murnane, and H. C. Kapteyn, “Observing the creation of electronic feshbach resonances in soft x-ray-induced O2 dissociation,” Science 322(5904), 1081–1085 (2008). [CrossRef] [PubMed]
  15. C. P. Hauri, W. Kornelis, F. W. Helbing, A. Heinrich, A. Couairon, A. Mysyrowicz, J. Biegert, and U. Keller, “Generation of intense, carrier-envelope phase-locked few-cycle laser pulses through filamentation,” Appl. Phys. B 79(6), 673–677 (2004). [CrossRef]
  16. C. P. Hauri, A. Guandalini, P. Eckle, W. Kornelis, J. Biegert, and U. Keller, “Generation of intense few-cycle laser pulses through filamentation - parameter dependence,” Opt. Express 13(19), 7541–7547 (2005). [CrossRef] [PubMed]
  17. A. Couairon, J. Biegert, C. P. Hauri, W. Kornelis, F. W. Helbing, U. Keller, and A. Mysyrowicz, “Self-compression of ultra-short laser pulses down to one optical cycle by filamentation,” J. Mod. Opt. 53(1-2), 75–85 (2006). [CrossRef]
  18. G. Stibenz, N. Zhavoronkov, and G. Steinmeyer, “Self-compression of millijoule pulses to 7.8 fs duration in a white-light filament,” Opt. Lett. 31(2), 274–276 (2006). [CrossRef] [PubMed]
  19. A. Guandalini, P. Eckle, M. Anscombe, P. Schlup, J. Biegert, and U. Keller, “5.1 fs pulses generated by filamentation and carrier envelope phase stability analysis,” J. Phys. At. Mol. Opt. Phys. 39(13), S257–S264 (2006). [CrossRef]
  20. X. W. Chen, X. F. Li, J. Liu, P. F. Wei, X. C. Ge, R. X. Li, and Z. Z. Xu, “Generation of 5 fs, 0.7 mJ pulses at 1 kHz through cascade filamentation,” Opt. Lett. 32(16), 2402–2404 (2007). [CrossRef] [PubMed]
  21. J. Y. Park, J. H. Lee, and C. H. Nam, “Laser chirp effect on femtosecond laser filamentation generated for pulse compression,” Opt. Express 16(7), 4465–4470 (2008). [CrossRef] [PubMed]
  22. A. Zaïr, A. Guandalini, F. Schapper, M. Holler, J. Biegert, L. Gallmann, U. Keller, A. Couairon, M. Franco, and A. Mysyrowicz, “Spatio-temporal characterization of few-cycle pulses obtained by filamentation,” Opt. Express 15(9), 5394–5404 (2007). [CrossRef] [PubMed]
  23. D. Walter, S. Eyring, J. Lohbreier, R. Spitzenpfeil, and C. Spielmann, “Spatial optimization of filaments,” Appl. Phys. B 88(2), 175–178 (2007). [CrossRef]
  24. T. Pfeifer, L. Gallmann, M. J. Abel, D. M. Neumark, and S. R. Leone, “Circular phase mask for control and stabilization of single optical filaments,” Opt. Lett. 31(15), 2326–2328 (2006). [CrossRef] [PubMed]
  25. A. Couairon, M. Franco, A. Mysyrowicz, J. Biegert, and U. Keller, “Pulse self-compression to the single-cycle limit by filamentation in a gas with a pressure gradient,” Opt. Lett. 30(19), 2657–2659 (2005). [CrossRef] [PubMed]
  26. A. Couairon, M. Franco, G. Mechain, T. Olivier, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures: Part I: Theory and numerical simulations,” Opt. Commun. 259(1), 265–273 (2006). [CrossRef]
  27. G. Mechain, T. Olivier, M. Franco, A. Couairon, B. Prade, and A. Mysyrowicz, “Femtosecond filamentation in air at low pressures. Part 11: Laboratory experiments,” Opt. Commun. 261(2), 322–326 (2006). [CrossRef]
  28. Q. Luo, S. A. Hosseini, W. Liu, J. F. Gravel, O. G. Kosareva, N. A. Panov, N. Akozbek, V. P. Kandidov, G. Roy, and S. L. Chin, “Effect of beam diameter on the propagation of intense femtosecond laser pulses,” Appl. Phys. B 80, 35–38 (2005). [CrossRef]
  29. S. Skupin, G. Stibenz, L. Bergé, F. Lederer, T. Sokollik, M. Schnürer, N. Zhavoronkov, and G. Steinmeyer, “Self-compression by femtosecond pulse filamentation: experiments versus numerical simulations,” Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 74(5 Pt 2), 056604 (2006). [CrossRef] [PubMed]
  30. N. Zhavoronkov, “Fine control of self-compression dynamics in a femtosecond filament,” J. Opt. A, Pure Appl. Opt. 11(12), 125201 (2009). [CrossRef]
  31. A. Couairon, “Dynamics of femtosecond filamentation from saturation of self-focusing laser pulses,” Phys. Rev. A 68(1), 015801 (2003). [CrossRef]

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