Blue-phase liquid crystal (BPLC) is introduced into the pores of capillary arrays to fabricate fiber arrays. Owing to the photonic-crystals like properties of BPLC, these fiber arrays exhibit temperature dependent photonic bandgaps in the visible spectrum. With the cores maintained in isotropic as well as the Blue phases, the fiber arrays allow high quality image transmission when inserted in the focal plane of a 1x telescope. Nonlinear transmission and optical limiting action on a cw white-light continuum laser is also observed and is attributed to laser induced self-defocusing and propagation modes changing effects caused by some finite absorption of the broadband laser at the short wavelength regime. These nonlinear and other known electro-optical properties of BPLC, in conjunction with their fabrication ease make these fiber arrays highly promising for imaging, electro-optical or all-optical modulation, switching and passive optical limiting applications.

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Abstract-We provide a critical account of the dynamics of laser induced refractive index changing mechanisms in nematic liquid crystals which may be useful for all-optical switching and modulation applications in the visible as well as the Terahertz and long-wavelength regime. In particular, the magnitude and response times of optical Kerr effects associated with director axis reorientation, thermal and order parameter changes, coupled flow-reorientation effects and individual molecular electronic responses are thoroughly investigated and documented, along with exemplary experimental demonstrations. Emphases are placed on identifying parameter sets that will enable all-optical switching with much faster response times compared to their conventional electro-optics counterparts.

We present a theoretical analysis supported by comprehensive numerical simulations of quasi-phase-matched four-wave mixing (FWM) of ultrashort optical pulses that propagate in weakly width-modulated silicon photonic nanowire gratings. Our study reveals that, by properly designing the optical waveguide such that the interacting pulses copropagate with the same group velocity, a conversion efficiency enhancement of more than 15 dB, as compared to a uniform waveguide, can readily be achieved. We also analyze the dependence of the conversion efficiency and FWM gain on the pulse width, time delay, walk-off parameter, and grating modulation depth.