Gilles J. Benoit

Wavelength-scalable hollow optical fibres with large photonic bandgaps for CO 2 laser transmission

Conventional solid-core optical fibres require highly transparent materials. Such materials have been difficult to identify owing to the fundamental limitations associated with the propagation of light through solids, such as absorption, scattering and nonlinear effects. Hollow optical fibres offer the potential to minimize the dependence of light transmission on fibre material transparency. Here we report on the design and drawing of a hollow optical fibre lined with an interior omnidirectional dielectric mirror. Confinement of light in the hollow core is provided by the large photonic bandgaps established by the multiple alternating submicrometre-thick layers of a high-refractive-index glass and a low-refractive-index polymer. The fundamental and high-order transmission windows are determined by the layer dimensions and can be scaled from 0.75 to 10.6 µm in wavelength. Tens of metres of hollow photonic bandgap fibres for transmission of carbon dioxide laser light at 10.6 µm wavelength were drawn. The transmission losses are found to be less than 1.0 dB m-1, orders of magnitude lower than those of the intrinsic fibre material, thus demonstrating that low attenuation can be achieved through structural design rather than high-transparency material selection.

Hollow multilayer photonic bandgap fibers for NIR applications

Here we report the fabrication of hollow-core cylindrical photonic bandgap fibers with fundamental photonic bandgaps at near-infrared wavelengths, from 0.85 to 2.28 microm. In these fibers the photonic bandgaps are created by an all-solid multilayer composite meso-structure having a photonic crystal lattice period as small as 260 nm, individual layers below 75 nm and as many as 35 periods. These represent, to the best of our knowledge, the smallest period lengths and highest period counts reported to date for hollow PBG fibers. The fibers are drawn from a multilayer preform into extended lengths of fiber. Light is guided in the fibers through a large hollow core that is lined with an interior omnidirectional dielectric mirror. We extend the range of materials that can be used in these fibers to include poly(ether imide) (PEI) in addition to the arsenic triselenide (As(2)Se(3)) glass and poly(ether sulfone) (PES) that have been used previously. Further, we characterize the refractive indices of these materials over a broad wavelength range (0.25 - 15 microm) and incorporated the measured optical properties into calculations of the fiber photonic band structure and a preliminary loss analysis.

Dynamic all-optical tuning of transverse resonant cavity modes in photonic bandgap fibers

Photonic bandgap fibers for transverse illumination containing half-wavelength microcavities have recently been designed and fabricated. We report on the fabrication and characterization of an all-optical tunable microcavity fiber. The fiber is made by incorporating a photorefractive material inside a Fabry-Perot cavity structure with a quality factor Q >200 operating at 1.5 microm. Under short-wavelength transverse external illumination, a 2 nm reversible shift of the cavity resonant mode is achieved. Dynamic all-optical tuning is reported at frequencies up to 400 Hz. Experimental results are compared with simulations based on the amplitude and kinetics of the transient photodarkening effect measured in situ in thin films.

Efficient LED light distribution cavities using low loss, angle-selective interference transflectors

Recent advances in solid state light source efficiency and luminance present the technical challenge of distributing light from very small point sources to large areas, with area distribution ratios having orders of magnitude greater than previously addressed. Broad adoption of LEDs in lighting and liquid crystal displays is in part contingent on addressing this fundamental light distribution issue. Here we present new materials based on giant birefringent nanotechnology which address these deficiencies allowing us to guide light in air via a novel light distribution system. Resulting from controlled in-plane and out-of-plane x,y,z refractive indices of adjacent layers, these multilayer interference films possess both angle selective and polarization selective reflectance. The angle selectivity can be tuned in both azimuth and polar angle, relieving a key constraint of prior materials. Our work has been done on a physically large scale enabling demonstration of large light management systems of industrial and practical relevance.

60.1: LCD Integrated Optics

A new class of optical film is demonstrated which addresses fundamental and longstanding constraints in LCD backlights. These films enable displays with highly integrated optics and no free-floating films. Both unitary polarized solid light guides and edge-lit hollow systems without guides are shown. The non-incremental impact on multiple LCD value propositions including waste stream is discussed. Film development has been done on manufacturing scale.