Nano-optical devices

Near-field observation of the optical field distribution in the nanostructures reveals a wealth of information about the enhancement mechanism of the optical field and will give useful guidelines to design a desirable SERS substrate. It is also practically important to consider the potential applications of the confined optical fields to nano-optical devices, bioimaging, and photochemical reactions. 

A method to obtain nano-particles at air/water interfaces has been described in [287]. Spreading of surfactant-coated metallic, semi-conducting, magnetic and ferroelectric nanoparticles on water surfaces results in the formation of monoparticulate thick films which then can be transferred, layer by layer, to solid substrates. These films can find potential applications in advanced electronic and electro-optical devices. Here and further, we give only typical examples of using surfactants in novel technologies. A more detailed description can be found in a new edition of Surfactants Science Series [288]. 

For the future work, elastomer tunable optofluidic devices are expected to extend into the nano-optics or nanofluidic fields. Several tunable nano-optical antenna devices fabricated on a stretchable PDMS substrate have been demonstrated recently. Combining elastomer-based micro/nano-devices with nanoplasmonic elements can be interesting for molecule-level imaging and spectroscopy. A tunable elastic nanofluidic channel was demonstrated recently on a PDMS chip for nanoparticle separation and molecule trapping [12]. One of the challenges of PDMS-based tunable nano-devices is to realize the high accuracy in control. High-precision control of PDMS-based tunable structures could be realized by very fine pneumatic actuation or connection to a piezo-actuator. 

The concept behind optical devices which incorporate liquids as a fundamental part of the optical structure can be traced at least as far back as the eighteenth century where rotating pools of mercury were proposed as a simple technique to create smooth spherical mirrors for use in reflecting telescopes. Modem microfluidics has enabled the development of a present-day equivalent of such devices, the development of which we now refer to as optofluidics. As will be described below, the capabilities in terms of fluidic control, mixing, miniaturization, and optical property tuning afforded by micro-, nano-, and electro-fluidics combined with soft lithography-based fabrication provide an ideal platform upon which to build such devices. 

Nevertheless, interest in these systems remains high for the future if these limiting issues can be addressed, for example by advances in materials science, nano-optics and device design. ... 

CdSe thin-film transistors were used in LCDs in 1973. Develc )ed for use in optoelectronic devices, laser diodes, nano-sensing, biomedical imaging and film solar cells. CdSe QDs have potential use in optical devices, such as laser diodes that can cover a large part of the visible spectrum ... 

Within the last decade the use of nanoclusters for novel (bio)electronic and (bio)optical devices gained world-wide attention due to a number of key-developments describe in this article. Furthermore, attempts to reduee the size of electronic devices with top down techniques will encounter insurmountable barriers due to limits of UV-lithography. The use of colloidal particles as elements and building blocks for new devices is a novel and cost efficient route. Bio-nano-assemblies will enable us to construct three-dimensional electronic circuits of ultra-high packing density. Manufacturing of bio-nano-devices will require the development of a completely new set of techniques to arrange, manipulate and couple colloidal particles. 

In optical devices regular arrays of nano-clusters give a very sharp resonance signal due to the large number of cooperative interactions in between the particles. Whereas this effect allows precise resonance tuning the same cooperative effect limits the dynamic range of the reaction if used for direct analyte detection. E.g. DNA-covered nano-clusters... 

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