COPULCO · Cascaded Optical Pulse Compressor

Cascaded Optical Pulse Compressor

This section normally should not exceed 2 pages. This is a comprehensive summary overview of results, conclusions and the socio-economic impacts of the project. The publishable report shall be formatted to be printed as a stand alone paper document. This report should address a wide audience, including the general public. Please ensure that it: • Is of suitable quality to enable direct publication by the REA or the Commission. • Is comprehensive, and describes the work carried out to achieve the project's objectives; the main results, conclusions and their potential impact and use and any socio-economic impact of the project. Please mention any target groups such as policy makers or civil society for whom the research could be relevant. • Includes where appropriate, diagrams or photographs and the project logo, illustrating and promoting the work of the project. • Provides the address of the project Website (if applicable) as well as relevant contact details. In this project we studied cascaded quadratic soliton compressions (CQSC) in quadratic nonlinear waveguides. Formation and interaction of few-cycle solitons in a lithium niobate channel waveguide are numerically investigated and experimentally demonstrated. Quadratic (nonlinear) waveguides are well known not only inherit to the nonlinear properties from the material, but also have optical waveguide structures that could provide good guidance and confinement on the laser light beam. Basically the light is guided and propagated inside the channel waveguide to suppress the effects of light spatial diffractions and increase the pulsed laser intensities. Therefore, laser pulses with nano-joule (nJ) energy and high repetition rate can be operated, which are complementary solutions to CQSCs in bulk materials that operate high-energy, large-beam-size pulsed lasers. The solitons are created through a cascaded phase-mismatched second-harmonic generation process, which induces a dominant self-defocusing Kerr-like nonlinearity on the pump pulse. The inherent material self-focusing Kerr nonlinearity is overcome over a wide wavelength range, and self-defocusing solitons are supported from 1100 to 1900 nm, covering the whole communication band. Single cycle self-compressed solitons and supercontinuum generation spanning 1.3 octaves are observed when pumped with femtosecond nanojoule pulses at 1550 nm. On the other hand, the dispersion engineering is possible through the design on the waveguide structure. We obtain an understanding of soliton spectral tunneling (SST) effect and use novel nonlinear phenomena to extend the conversion regimes. With a more extreme dispersion engineering, the normal dispersion range can be largely extended towards long wavelengths beyond the material zero dispersion wavelength (ZDW) and even an all-normal dispersion profile can be achieved, which could extend the CQSC into the near-infrared range (near-IR) and mid-infrared range (mid-IR), since the overall self-defocusing nonlinearity is always broadband far beyond the material ZDW.

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