Optical Cherenkov radiation in ultrafast cascaded second-harmonic generation

Journal Article · Wed Dec 15 00:00:00 EST 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.82.063806· OSTI ID:21528966

Bache, M; Bang, O; Zhou, B B ^[1]; Moses, J ^[2]; Wise, F W ^[3]

---

1. DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)
2. Optics and Quantum Electronics Group, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
3. Department of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States)

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 ({beta}-barium borate) is found for pump wavelengths in the range {lambda}=0.95-1.45 {mu}m, and is located in the regime {lambda}=1.5-3.5 {mu}m. 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 dynamics rather than generation of Cherenkov radiation.

• OSTI ID: 21528966
• Journal Information: Physical Review. A, Vol. 82, Issue 6; Other Information: DOI: 10.1103/PhysRevA.82.063806; (c) 2010 American Institute of Physics; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
BARIUM COMPOUNDS
BORATES
CHERENKOV RADIATION
CRYSTALS
HARMONIC GENERATION
INFRARED RADIATION
OSCILLATIONS
PEAKS
PULSES
PUMPING
SOLITONS
SPECTRA
WAVELENGTHS
ALKALINE EARTH METAL COMPOUNDS
BORON COMPOUNDS
ELECTROMAGNETIC RADIATION
FREQUENCY MIXING
OXYGEN COMPOUNDS
QUASI PARTICLES
RADIATIONS
SORPTION