Optical limiting, pulse reshaping, and stabilization with a nonlinear absorptive fiber system

Functional Materials Based on Metal-Containing Polymers

Since the dawn of human civilization, there has been a demand for materials that include ceramics, metals, and polymers. Increasing demand as well as the need for enhanced performance has driven material scientists to research metal-containing polymers as complements of these materials. Consequently, metal-containing polymers that integrate the excellent thermal, electronic, optical, and magnetic properties of metals with the lightweight, low cost, and in some cases, the chemical stability of organic-based polymers have been designed, and used as catalysts, sensors, ceramic precursors, magnetic materials, and electrical conductors. This chapter provides an overview of some of these functional metal-containing polymers.

Conjugated polymer-fullerene blend with strong optical limiting in the near-infrared

Optical-quality, melt processable thick films of a conjugated polymer blend containing poly(2-methoxy-5-(2-ethyl-hexyloxy)-(phenylene vinylene)) (MEH-PPV), a C(60) derivative (PCBM) and a plasticizer (1,2-di-iso-octylphthalate) have been developed and their nonlinear absorption and optical limiting properties have been investigated. These blend materials exhibited strong optical limiting characteristics in the near infrared region (750-900 nm), with broad temporal dynamic range spanning femtosecond to nanosecond pulse widths. The dispersion of the optical limiting figure-of-merit of the MEH-PPV:PCBM:DOP blend shows a peak near the wavelength of the MEH-PPV cation, indicating an important role of one-photon and two-photon induced charge transfer in the nonlinear absorption response.

Metalloporphyrin polymer with temporally agile, broadband nonlinear absorption for optical limiting in the near infrared

A lead bis(ethynyl)porphyrin polymer possesses strong nonlinear absorption with unprecedented spectral/temporal coverage as a result of broad, overlapping two-photon and excited-state absorption bands with favorable excited-state dynamics. Consequently, this material exhibits effective optical limiting over a range of about 500 nm in the near infrared (ca. 1050 - 1600 nm) and for laser pulsewidths spanning from 75 fs to 40 ns. Introduction of the material in a waveguide device geometry results in a strong optical limiting response.

Significant enhancement of broadband optical limiting behavior using off-resonant sub-wavelength coupled plasmonic waves

We present the numerical investigation of the optical limiting behavior based on coupled nonlinear plasmonic waveguides. Exploiting the strong localization of the electromagnetic fields at metal-dielectric interfaces, significant enhancement of the nonlinear absorption was achieved. Two types of optical limiters (OLs), one based on the enhanced optical Kerr (OK) effect and the other based on the enhanced two-photon absorption (TPA), are proposed. Their transmission characteristics at off-resonant band of Au are investigated. The simulation results reveal that the linear transmittances in both cases are higher than 85%, and the limiting thresholds are 250 GW/cm(2) and 42.69 GW/cm(2) for the OK and TPA based OLs, respectively. As compared with the non-structured slab waveguides, the optical limiting thresholds are greatly reduced. Wideband operation over 200 nm was confirmed and TPA induced free carrier absorption (FCA) discussed.

Optical limiting properties of nonlinear multimode waveguides

An experimental investigation of the transmission of multimode capillary waveguides with a nonlinear absorber in the core shows an enhanced nonlinear absorption relative to the same length of bulk material. The results are consistent with partial mode filling within the cores of the waveguides. This study confirms the promising optical limiting capabilities of multimode nonlinear waveguides and implies that the mode structure should be considered in the design and evaluation of capillary array optical limiters.