Photonic crystal fibers (PCFs) are a special class of optical fibers with a periodic arrangement of microstructured holes located in the fiber’s cladding. Light confinement is achieved by means of either index-guiding, or the photonic bandgap effect in a low-index core. Ever since PCFs were first demonstrated in 1995, their special characteristics, such as potentially high birefringence, very small or high nonlinearity, low propagation losses, and controllable dispersion parameters, have rendered them unique for many applications, such as sensors, high-power pulse transmission, and biomedical studies. When the holes of PCFs are filled with solids, liquids or gases, unprecedented opportunities for applications emerge. These include, but are not limited in, supercontinuum generation, propulsion of atoms through a hollow fiber core, fiber-loaded Bose–Einstein condensates, as well as enhanced sensing and measurement devices. For this reason, infiltrated PCF have been the focus of intensive research in recent years. In this review, the fundamentals and fabrication of PCF infiltrated with different materials are discussed. In addition, potential applications of infiltrated PCF sensors are reviewed, identifying the challenges and limitations to scale up and commercialize this novel technology.

Photonic crystal fibers (PCF) have been selectively filled with a cholesteric liquid crystal (ChLC) with special interest in the blue phase (BP) of the liquid crystal. It has been observed thermal tuning of the guided light in the visible region. A dramatically enhance appears when the phase of the liquid crystal changes from cholesteric to blue phase I (BPI). When a thermal range of the blue phase I is achieved, no changes are observed while increasing temperature from BPI through BPII and to the isotropic phase.

The peculiar optical response of polydimethylsiloxane (PDMS) doped with metallic nanoparticles can be employed to develop optical sensing materials. These nanocomposites may work in an ample range of temperatures, showing good linearity and high sensitivity. Plasmon resonances of the metallic nanoparticles produce interesting effects on the optical response by affecting the effective refractive index of PDMS. The high resonant response leads to a number of different configurations of optical filters and phase devices whose resonant frequency depends on the chosen nanoparticle. Moreover, the wavelength can be tuned up by external manufacturing conditions such as nanoparticle size or fill factor, and by working parameters such as temperature. This work develops the theoretical background required for the design of these structures, and evaluates the adequate dimensional and doping ranges for device optimization.

We have evaluated the performance for space applications of commercial off-the-shelf fiber coupled optical switches with no-moving parts, based on different technologies. The technical requirements of several space applications of optical switches were defined. After the technology selection, a tradeoff was performed to select the final optical switches to be tested, which are based on three technologies (Magneto-Optic MO, Bulk Electro-Optic B-EO, and Waveguide Electro-Optic W-EO) and fabricated by four different manufacturers. Other potential technologies (acoustooptic, liquid crystal, thermo-optic, micro/nano photonic waveguides) were not selected due to the lack of commercial products. A test campaign was carried out, consisting of thermal vacuum cycles, mechanical tests (vibration and shocks) and radiation tests (gamma radiation). The main performance parameters were the insertion loss, crosstalk, and switching speed. After the final electro-optical characterization, a destructive physical analysis was made to some optical switches. The results of the tests indicated that B-EO and MO technologies are excellent candidates for the analyzed space applications. They respond very well under typical space conditions as radiation, vibration, shocks and thermal vacuum; B-EO technology presents lower switching time but its crosstalk is worse. WG-EO technology is very fast, but a mechanical failure in one device was observed, the insertion losses are very high and the crosstalk is very low.

Abstract-Selectively filled photonic crystal fibers with polydimethylsiloxane (PDMS), a silicon-type material, have been studied. It has been demonstrated that polarization properties of these hybrid devices change and so do the properties of guided light in relation with temperature, finding that the state of polarization (SOP) changes with an increasing temperature but remains constant for a wide spectrum of wavelengths for a determinate temperature.

Abstract:A photonic crystal fiber selectively filled with silver nanoparticles dispersed in polydimethylsiloxane has been numerically studied via finite elements analysis. These nanoparticles possess a localized surface plasmon resonance in the visible region which depends on the refractive index of the surrounding medium. The refractive index of polydimethylsiloxane can be thermally tuned leading to the design of polarization tunable filters. Filters found with this setup show anisotropic attenuation of the x-polarization fundamental mode around a x = l200dB/cm remarkably higher than the y-polarization mode. Moreover, high fiber birefringence and birefringence reversal is observed in the spectral region of the plasmon. References and links1. J. C. Knight, T. A. Birks, P. St. J. Russell, and D. M. Atkin, "All-silica single-mode optical fiber with photonic crystal cladding," Opt. Lett. 21, 1547Lett. 21, -1549Lett. 21, (1996.

Abstract-Policryps structures of photo-curable adhesive NOA61

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