Extreme Photonics

filamentAdvances in nonlinear optics are tightly interlinked with performance of high peak power coherent light sources. We utilize techniques such as OPA and OPCPA for waveform engineering of controlled intense light fields across the UV to the mid-IR spectral range. These sources have reached top performance with e.g. 2000 nm, 3-cycle duration, self-CEP stable and with 1 mJ pulse energy at 4 kHz. Current interest lies in the long wavelength range with sources tunable or operating at 2000 nm, 3100 nm, 6000 nm and beyond.

Extreme photonics is concerned with the interaction of intense light fields with matter. For instance, we investigate, and use physical phenomena such as filamentation to study X-wave generation. We have made pioneering contributions, e.g. achieving one of the shortest pulse durations (3.7 fs at 800 nm) and introduced filamentation for the generation of intense sub-2-cycle light fields. Recent breakthroughs include the first demonstration of a >3-octave-wide and coherent supercontinuum and first self-compression in bulk media to the two-cycle regime without chirped mirrors and 80% efficiency.


OURCONTRIBUTIONS

Coherent Supercontinua

MIRscUsing a 3.1-μm optical parametric chirped-pulse amplifier (OPCPA), we generate a supercontinuum in a step-index chalcogenide fiber that spans from 1.6 to 5.9 μm at the −20 dB points. The rugged step-index geometry allows for long-term operation, while the spectral bandwidth is limited by the transmission of the As2S3 fiber.

  1. F. Silva, D. Austin, A. Thai, M. Baudisch, M. Hemmer, A. Couairon, J. Biegert, “Multi-octave supercontinuum from mid-IR filamentation in bulk”, Nature Commun. 3, 807 (2012)
  2. D. D. Hudson, M. Baudisch, D. Werdehausen, B. J. Eggleton, J. Biegert, “1.9 octave supercontinuum generation in a As2S3 step-index fiber driven by Mid-IR OPCPA”, Opt. Lett. 39, 5752 (2014)

Collapse and Selfcompression

MIR3cyc

We present the first demonstration of sub-3 cycle optical pulses at 3.1 μm central wavelength generated through self-compression in the anomalous dispersion regime in a dielectric. The pulses emerging from this compact and efficient self-compression setup could be focused to intensities exceeding 1014 W/cm<sup>2</sup>, a suitable range for high field physics experiments. Numerical simulations performed with a 3D nonlinear propagation code, provide theoretical insight on the processes involved and support our experimental findings.

  1. J. Biegert, and J.-C. Diels, ”Compression of pulses of a few optical cycles through harmonic generation”, J. Opt. Soc. Am. B 18, 1218-1226 (2001)
  2. A. Couairon, M. Franco, A. Mysyrowicz, J. Biegert, U. Keller, and, ”Pulse self-compression to the single cycle limit by filamentation in a gas with a pressure gradient”, Opt. Lett. 30, 2657-2659 (2005)
  3. A. Couairon, J. Biegert, C. P. Hauri, U. Keller, and A. Mysyrowicz, ”Self-generation of near-single-cycle pulses through filamentation”, invited paper, J. Mod. Opt 53(1-2), 75-85 (2006)
  4. M. Hemmer, M. Baudisch, A. Thai, A. Couairon, J. Biegert, “Self-compression to sub-3-cycle duration of mid-infrared optical pulses in dielectrics”, Opt. Exp. 22, 028095 (2013)

Filamentation and X-Waves

supercontinuumIn supercontinuum generation, various propagation effects combine to produce a dramatic spectral broadening of intense ultrashort optical pulses. With a host of applications, supercontinuum sources are often required to possess a range of properties such as spectral coverage from the ultraviolet across the visible and into the infrared, shot-to-shot repeatability, high spectral energy density and an absence of complicated pulse splitting. Here we present an all-in-one solution, the first supercontinuum in a bulk homogeneous material extending from 450 nm into the mid-infrared. The spectrum spans 3.3 octaves and carries high spectral energy density (2 pJ nm<sup>−1</sup>–10 nJ nm<sup>−1</sup>), and the generation process has high shot-to-shot reproducibility and preserves the carrier-to-envelope phase. Our method, based on filamentation of femtosecond mid-infrared pulses in the anomalous dispersion regime, allows for compact new supercontinuum sources.

  1. P. Rambo, J. Biegert, V. Kubecek, J. Schwarz, J.-C. Diels, R. Bernstein, and K. Stahlkop, ”Controlling lightning discharge with laser radiation – laboratory tests of laser induced lightning discharge”, J. of Opt. Technology 66, 194-198 (1999)
  2. C. P. Hauri, W. Kornelis, F. 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, 673-677 (2004)
  3. A. Couairon, M. Franco, A. Mysyrowicz, J. Biegert, U. Keller, and, ”Pulse self-compression to the single cycle limit by filamentation in a gas with a pressure gradient”, Opt. Lett. 30, 2657-2659 (2005)
  4. A. Couairon, J. Biegert, C. P. Hauri, U. Keller, and A. Mysyrowicz, ”Self-generation of near-single-cycle pulses through filamentation”, invited paper, J. Mod. Opt 53, 75-85 (2006)
  5. F. Silva, D. Austin, A. Thai, M. Baudisch, M. Hemmer, A. Couairon, J. Biegert, “Multi-octave supercontinuum from mid-IR filamentation in bulk”, Nature Commun. 3, 807 (2012)

Laser Guidestars and Coherent Excitation

naguidestarWe have theoretically determined and experimentally confirmed that polychromatic multiphoton coherent excitation can be used to most efficiently achieve a selective total population inversion in a multilevel system. These results suggest a solution to the problem of using mesospheric sodium as a guidestar.

  1. J.-C. Diels, J. Biegert, J. T. McGraw, ”Alternatives to the conventional sodium beacon”, Astronom. Soc. Pac. (Adapt. opt. interfer. 21st cent., ISBN 1-886733-96-1), 174, 81-85 (1999)
  2. J. Biegert, J.-C. Diels, “Feasibility study of a bichromatic guidestar – coherent 2-photon bichromatic excitation of mesospheric sodium”, OSA Trends in optics and photonics (Nonlin. Opt., ISBN 1-55752-646-X), 46, 28-30 (2000)
  3. J. Biegert, J.-C. Diels, and P. W. Milonni, ”Bichromatic two-photon coherent excitation of sodium to provide a dual-wavelength guidestar”, Opt. Lett., 25, 683 (2000)
  4. J. Biegert, and J.-C. Diels, ”Feasibility study to create a polychromatic guidestar in atomic sodium” Phys. Rev. A 65, 043403 (2003)

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