Photonic fabrication

Industrial Applications Photonic fabric display " Safety/Toxicity No data available... 

Tao, X. Cheng, X. Yu, J. Liu, L. Wong, W Tam, W. Photonic fabric display with controlled pattern, color, luminescence intensity, scattering intensity and light self-amplificatioa U.S. Pat. Appl. Publ. US 20070281155,2007. 

It is seen that the TPA rate quadratically depends on the light intensity, which is an important mechanism to improve the spatial resolution in two-photon fabrication. A high capability of materials to absorb photons via TPA is desired, which is described by TPA cross-section, 5, defined by... 

Fig. 9 A crossbeam two-photon two-color scanning laser microscopic system. Pulses from two beams split from an identical laser output should overlap in both time and temporal domains so that a TPA process could be launched by simultaneously absorbing two photons. Removal of the frequency shifter gives rise to a degenerative two-photon fabrication system...

Both of the above two researches targeted the drug delivery devices or sustained release devices. It is believed that the ability to fabricate with both hydrogel materials and proteins at milli-, micro- and nanoscales would expand the utility of such devices that are currently millimeter-sized. Critical to creating useful release devices is the entrapment of target molecules. For two-photon curing, the task was simplified to include only the molecules of the fabrication solution. Pitts et al. find that alkaline phosphatase maintains bioactivity after entrapment in the protein structure. As sustained release devices, it is found the rates of diffusion of fluorescently labeled dextrans (10 and 40 kDa) from a two-photon fabricated BSA matrix vary with molecular weight and are Hnearly correlated with cross-link density. The release half-life of 10 kDa dextran-TMR from a BSA microstructure is equal to or less than 6 minutes while that for 40 kDa dextran-TMR is 25 minutes. 

Designing tandem cells is complex. For example, each cell must transmit efficiently the insufficiently energetic photons so that the contacts on the backs of the upper cells are transparent to these photons and therefore caimot be made of the usual bulk metal layers. Unless the cells in a stack can be fabricated monolithically, ie, together on the same substrate, different external load circuits must be provided for each cell. The thicknesses and band gaps of individual cells in the stack must be adjusted so that the photocurrents in all cells are equal. Such an optimal adjustment is especially difficult because the power in different parts of the solar spectmm varies under ambient conditions. Despite these difficulties, there is potential for improvement in cell conversion efficiency from tandem cells. 

This article focuses primarily on the properties of the most extensively studied III—V and II—VI compound semiconductors and is presented in five sections (/) a brief summary of the physical (mechanical and electrical) properties of the 2incblende cubic semiconductors (2) a description of the metal organic chemical vapor deposition (MOCVD) process. MOCVD is the preferred technology for the commercial growth of most heteroepitaxial semiconductor material (J) the physics and (4) apphcations of electronic and photonic devices and (5) the fabrication process technology in use to create both electronic and photonic devices and circuits. 

Since IR detector materials are direct bandgap materials (with no change in electron momentum required), they are very efficient absorbers (and emitters) of light - all IR photons are absorbed within the first few /rm of material. The reason that infrared detectors are 10 to 15 ptm thick is for structural and fabrication reasons, not for light absorption reasons. 

The lead compounds PbS, PbSe, PbTe are narrow-gap semiconductors that have been widely investigated for infrared detectors, diode lasers, and thermo-photovoltaic energy converters. Their photoconductive effect has been utilized in photoelectric cells, e.g., PbS in photographic exposure meters. Integrated photonic devices have been fabricated by their heteroepitaxial growth on Si or III-V semiconductors. 

Figure 11.11. Integration of nanowire photonics with silicon electronics. Schematic illustrating fabrication of hybrid structures. A silicon-on-insulator (SOI) substrate is patterned by standard electron-beam or photolithography followed by reactive ion etching. Emissive NWs are then aligned onto the patterned SOI substrate to form photonic sources. [Reprinted with permission from Ref. 59. Copyright 2005 Wiley-VCH Verlag.]...

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