TY - JOUR
T1 - Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation
AU - Bache, Morten
AU - Bang, Ole
AU - Zhou, Binbin
AU - Moses, J.
AU - Wise, F.W.
PY - 2010
Y1 - 2010
N2 - We show through theory and numerics that when few-cycle femtosecond solitons are generated through
cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov
radiation in the form of linear dispersive waves located in the red part of the spectrum. The beating between the
dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of
a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering
around the dispersive wave peak results in near-transform-limited ultrashort mid-IR pulses with pulse durations
much shorter than the input near-IR pulse. The Cherenkov radiation for the crystal considered (β-barium borate)
is found for pump wavelengths in the range λ = 0.95–1.45 μm, and is located in the regime λ = 1.5–3.5 μm. For
shorter pump wavelengths, the phase-matching point is located in the absorption region of the crystal, effectively
absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency
conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter
away the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing
phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength
radiation that can occur during soliton compression. We discuss the conditions that lead to this alternative
AB - We show through theory and numerics that when few-cycle femtosecond solitons are generated through
cascaded (phase-mismatched) second-harmonic generation, these broadband solitons can emit optical Cherenkov
radiation in the form of linear dispersive waves located in the red part of the spectrum. The beating between the
dispersive wave and the soliton generates trailing temporal oscillations on the compressed soliton. Insertion of
a simple short-wave pass filter after the crystal can restore a clean soliton. On the other hand, bandpass filtering
around the dispersive wave peak results in near-transform-limited ultrashort mid-IR pulses with pulse durations
much shorter than the input near-IR pulse. The Cherenkov radiation for the crystal considered (β-barium borate)
is found for pump wavelengths in the range λ = 0.95–1.45 μm, and is located in the regime λ = 1.5–3.5 μm. For
shorter pump wavelengths, the phase-matching point is located in the absorption region of the crystal, effectively
absorbing the generated dispersive wave. By calculating the phase-matching curves for typically used frequency
conversion crystals, we point out that the mid-IR absorption in the crystal in many cases automatically will filter
away the dispersive wave. Finally, an investigation of recent experimental results uncovers a four-wave-mixing
phenomenon related to Cherenkov radiation that is an additional generation mechanism of long-wavelength
radiation that can occur during soliton compression. We discuss the conditions that lead to this alternative
U2 - 10.1103/PhysRevA.82.063806
DO - 10.1103/PhysRevA.82.063806
M3 - Journal article
VL - 82
SP - 1
EP - 13
JO - Physical Review A (Atomic, Molecular and Optical Physics)
JF - Physical Review A (Atomic, Molecular and Optical Physics)
SN - 2469-9926
ER -