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Special QO/AMO Seminar

Lecture I - Martijn deSterke

Title: Evanescent modes in slow-light photonic crystal waveguides

Photonic crystal waveguides are an excellent geometry for the observation of slow light, since the dispersion relation can be manipulated delicately. A perceived problem, based on a simple impedance-type argument, is that the coupling into a slow-light waveguide is inefficient. We recently showed that this is not necessarily so, because the simple argument ignores the presence of evanescent modes. I review these arguments and then present experimental results, taken at AMOLF in the Netherlands, explicitly confirming the presence of the evanescent modes in slow-light photonic crystal waveguides.

Lecture II- Irina Kabakova

Title: Bragg-grating based optical switching in highly-nonlinear bismuth-oxide fiber

Nonlinear Bragg Gratings (BGs) are ideal for studying dynamic optical effects in nonlinear periodic media. The one-dimensional photonic bandgap, in combination with a Kerr-type medium, leads to ultrafast (10s of femtoseconds) all-optical functions such as transmission (reflection) switching and power limiting. The main drawback of these techniques, implemented in conventional fibers, is optical power requirement as high as several kilowatts. To overcome this disadvantage we propose to use highly-nonlinear media for all-optical switching. In this talk, I demonstrate efficient transmission switching of an optical signal in a Bragg grating inscribed in highly-nonlinear bismuth-oxide fiber. The high nonlinear refractive index of the glass in combination with a small fiber core make possible to reduce the switching threshold from kilowatts to tens of watts.