Search

Second harmonic generation is an efficient way to create coherent radiation at wavelengths that are not accessible with standard laser sources. In this work we demonstrate second harmonic generation from 1550 to 775 nm in a polymer photonic integrated circuit via the hybrid integration of a periodically poled lithium niobate crystal. The bulk crystal is inserted in an on-chip free-space section between two waveguide coupled GRIN lenses. Fiber to fiber conversion efficiencies were 0.03%/W for a continuous wave laser source and 100%/W for a femtosecond laser source. Furthermore, third and fourth harmonic light at 517 and 388 nm was observed. [ABSTRACT FROM AUTHOR]

In this paper, we present a locally controllable liquid crystal lens array for a partially switchable 2D/3D display, from which 2D images without resolution degradation and 3D images can simultaneously emerge. The liquid crystal (LC) lens has the advantages of low driving voltages (<\6\ Vrms) and a simple structure for which the fabrication only requires two photolithography processes. A partial lens array can be formed arbitrarily using a passive driving method. Finally, we demonstrate a 3.5-in partially switchable 2D/3D display that can present partial 3D images with 10.8% crosstalk and partial 2D images without resolution degradation. [ABSTRACT FROM PUBLISHER]

In this letter, we introduce beam shapers that are designed using 1-D photonic crystals with a defect layer. We use two different radial gradient refractive index lenses as defect layers. Using the transfer matrix method, the properties of the structures are investigated. As a result, the proposed devices can shape and modulate the phase and intensity of plane waves on the output plane. It is possible to engineer different parameters, such as the refractive index distribution function of the defect layer and incident wave frequency, to achieve desired and useful beam shapes that are required for a given application. [ABSTRACT FROM PUBLISHER]

Abstract: Gaussian beam propagation through a novel high refractive index contrast nanostructured Gradient-Index (GRIN) microlens with an arbitrary refractive index distribution is investigated. The concept of the nanostructured GRIN microlenses is based on the effective medium theory and we show numerically, using the FDTD method, that nanostructured GRIN microlenses can focus Gaussian beams in an identical manner to conventional GRIN microlenses. Nanostructured GRIN microlenses have a reduced thickness by almost two orders of magnitude compared to conventional GRIN lenses. We also investigate the accuracy of the standard scalar and paraxial GRIN theory in the case of a very high contrast nanostructured GRIN microlens. The paraxial GRIN lens theory is shown only to give an approximate description of Gaussian beam propagation in such a high contrast nanostructured GRIN microlens. [Copyright &y& Elsevier]

We report a new addressing mechanism for quasi-distributed absorption sensors based on the frequency modulated continuous wave (FMCW) method. The sensor units consist of open-path microoptic cells constructed from gradient index (GRIN) lenses, each of differing lengths. Coherence addressing of the cells using FMCW is achieved by the interferometric mixing of two signals originating from each cell (from the glass/air interfaces). The time delay between the two reflections, along with the linear frequency ramp of the source, gives rise to beat frequencies in the mixed output which are different for each cell. The connecting fiber length between two successive sensor cells is chosen to be much greater than the coherence length of the source so that the reflections from different cells do not interfere. The interference patterns of all sensor cells add up at the detector whereby each individual sensing cell is identified, by its power spectrum in the frequency domain. We show theoretically and experimentally how individual cells can be addressed and the measured signals obtained by suitable choice of cell length, proper modulation of the source and appropriate signal processing [ABSTRACT FROM PUBLISHER]

Gradient-index fiber lenses are used to fabricate high-strength (>100 kpsi) low-loss fusion splices between two microstructured optical fibers (as low as 0.40 dB) or between a microstructured fiber and a conventional optical fiber (as low as 0.44 dB). This approach overcomes the deleterious effects of heat-induced air-hole collapse, which has until now been an important limitation when fusion splicing microstructured optical fibers. [ABSTRACT FROM PUBLISHER]