A number of approaches have been developed for in-vivo imaging of neural function at the time scale of action potentials and at the spatial resolution of individual neurons. Remarkable results have been obtained with optogenetics, although the need for genetic modification is an important limitation of these approaches. Similarly, voltage and ion-sensitive dyes allow for optical imaging of action potentials but toxicity remains a problem. Additionally, optical techniques are often only able to be used up to a limited depth. Our preliminary work has shown that nanoparticles of common phosphorescent materials, believed to be generally non-toxic, specifically lutetium oxide and strontium aluminate, can be utilized for cellular imaging, for tomographic imaging, and that the particles can be designed to adhere to neurons. Additionally, lutetium oxide has been shown to be highly X-ray luminescent, potentially allowing for imaging deep within the brain, if the particles can be targeted properly. In ex vivo experiments, we have shown that the phosphorescence of strontium aluminate particles is significantly affected by electric fields similar in strength to those found in the vicinity of the cellular membrane of a neuron. This phenomenon is consistent with early published reports in the electroluminescence literature, namely the Gudden-Pohl effect. We will show results of the ex vivo imaging and dynamic electrical stimulation experiments. We will also show some preliminary ex vivo cell culture results, and will describe plans for future research, focusing on potential in both cell cultures and in vivo for animal models.
Efficient light extraction from organic light emitting diode (OLED) is challenging and efforts are being made to come up with efficient & cost effective outcoupling techniques. We demonstrate 50% EQE entitlement from solution processed white OLEDs compared to 33% EQE observed in devices, implying that there is plenty of room to improve the efficiency of white OLEDs. We present challenges in efficient light extraction from solution processed OLEDs that need to be overcome to close the efficiency gap. We also demonstrate a novel characterization technique that is effective in estimating the light extraction efficiency of outcoupling films and can expedite the selection and optimization of various light extraction approaches without the need to build OLEDs.
Holographic data storage materials are presented that are based on a thermoplastic host doped with narrow-band
absorption dyes. The dyes are photosensitive and undergo non-reversible photobleaching reactions upon exposure.
Samples were produced using different dyes and various concentrations in a polymer host with a focus on sensitivity and
capacity of the media. A challenging obstacle for a successful dye-doped system is the inherent remaining
photosensitivity of the material after the writing process. This paper will introduce the concept of a highly sensitive yet
non-volatile dye-based data storage system. The chromophore is subjected to a post-treatment step at a second
wavelength which removes the photosensitivity. The stored data can therefore be secured against degradation during
read-out at the writing wavelength.
Holographic data storage materials based on a dye-doped thermoplastic that could find application in professional archival and consumer applications are described. The dye is selected from the class of o-nitrostilbenes, which irreversibly bleaches under exposure to light and shows high thermal stability before and after exposure. The reduction in concentration of the dye in the host after exposure induces refractive index variations over a wide range of wavelengths and extends well away from the dye absorption peak conforming to the Kramers-Kronig relationship. The materials are injection moldable into the standard disc format and have negligible shrinkage during data storage. Samples were produced using different dyes and various concentrations in a polycarbonate host and processed on professional CD/DVD equipment. The refractive index change is as high as 0.04, with a measured instantaneous sensitivity of 0.5 cm/J and M/# = 0.3.
This paper updates the recent progress in the micro-holographic format data recorded in our second-generation dye-doped thermoplastic medium. This new medium is about 400 times more sensitive than our first generation material, while our single-bit system needs less than 2.3 milliseconds to write a micro-hologram. The characteristics of micro-holograms recorded in the high sensitivity material are presented and compared to earlier results from the first-generation low-sensitivity material.
Holographic data storage materials are currently being developed at General Electric. These materials are based on a thermoplastic host doped with narrow-band absorption dyes. The dyes are photosensitive and undergo non-reversible photochromic reactions upon exposure. Samples were produced using different dyes and various concentrations in a polycarbonate host with a focus on sensitivity and capacity of the media. A challenging obstacle for a successful photochromic system is the inherent remaining photosensitivity of the material after the writing process. This paper will introduce the concept of a highly sensitive yet non-volatile photochromic data storage system. The chromophore is subjected to a post-treatment step at a second wavelength which removes the photosensitivity. The stored data can therefore be secured against degradation during read-out at the writing wavelength.
The growing prevalence of digital technologies has led to increased data generation so that new storage technologies must be developed to handle expanding capacity demand. Holographic data storage is a very promising candidate with the potential to provide ultra-high density data storage. Currently, many teams are developing holographic storage technology, with much of the emphasis on professional archival applications. However, consumer-oriented applications are also growing rapidly and the requirements for these applications are different from those for professional archival storage. In particular, a holographic medium for consumer applications must be simple, cheap, and easy to process. In addition, where content distribution is the intended application, the medium must also be compatible with mastering and replication processes. We present a new holographic medium designed to meet the requirements of consumer oriented applications. The media is based on thermoplastic materials that are modified by the inclusion of photo-chemically active dyes. A series of 0.6 and 1.2 mm thick discs were injection molded and characterized for holographic storage capacity and sensitivity. The first series of samples showed large refractive index modulations of 0.03 but a poor sensitivity of 0.1 cm/J. Analysis of the data showed that the low sensitivity limited the usable capacity of the media to M/# values of ~1. A new series of dyes were synthesized with optimized efficiency and injection molded in 1.2 mm substrates. These substrates demonstrated comparable usable capacity but with significantly increased sensitivities. The results of the measurements of the injection-molded thermoplastic media are presented.
A new holographic data storage material based on narrow-band absorption is currently being developed at General Electric. Experimental characterization results of the preliminary materials are presented.
Very Small Aperture Laser (VSAL) system is a near field optical data storage system that utilizes a nano-aperture fabricated at the front facet of a semiconductor laser to define a nano-sized spot and hence to achieve ultra-high density storage. However, these nano-apertures typically have very poor power throughput behavior when the sizes of the apertures are much smaller than the wavelength of the incident light. In this paper, we use numerical simulation tool XFDTD, which is a three-dimensional vector electro-magnetic field simulator based on the finite difference time domain (FDTD) method, to study the behavior of the nano-apertures. We show that for square apertures, the power throughput decays as r4 (r is the size of the aperture) when the aperture size r is less than lamda/4 (lamda is the incident light wavelength). To solve the power throughput shortage problem, we present our novel nano-aperture design -'C'-aperture. Compared with a conventional 100nm square aperture, the 'C'-aperture provides 1000x higher power throughput while maintaining a comparable near field spot size. We show that the greatly enhanced power throughput is due to both the polarization and resonance effects.