Optical Data Link Employing Organic Light-Emitting Diodes and Organic Photodiodes as Optoelectronic Components

An optical interconnect solely using organic optoelectronic components is presented. The data link is based on an organic light-emitting diode as the transmitter and an organic photodiode as the receiver. Light is transmitted via a polymer optical fiber coupled to the active components. A digitized audio signal based on the Sony/Philips Digital Interface Format standard at a signal bit rate of 2.8224 Mbit/s (44.1-kHz sampling frequency) is successfully transmitted.     

Coupling of Organic Semiconductor Amplified Spontaneous Emission Into Polymeric Single-Mode Waveguides Patterned by Deep-UV Irradiation

Single-mode waveguides were fabricated by deep ultraviolet radiation in poly(methyl methacrylate) (PMMA). Using a masking process, the radiation modifies the refractive index of the PMMA forming core and cladding regions for waveguiding. Following the fabrication of the waveguides, the small molecule material aluminum tris(8-hydroxyquinoline) doped with the laser dye DCM is deposited directly onto the waveguide structures. By optical pumping (lambda=355 nm) amplified spontaneous emission was observed at the end facets of the waveguides     

A non-farnesylated Ha-Ras protein can be palmitoylated and trigger potent differentiation and transformation

Ha-Ras undergoes post-translational modifications (including attachment of farnesyl and palmitate) that culminate in localization of the protein to the plasma membrane. Because palmitate is not attached without prior farnesyl addition, the distinct contributions of the two lipid modifications to membrane attachment or biological activity have been difficult to examine. To test if palmitate is able to support these crucial functions on its own, novel C-terminal mutants of Ha-Ras were constructed, retaining the natural sites for palmitoylation, but replacing the C-terminal residue of the CAAX signal for prenylation with six lysines. Both the Ext61L and ExtWT proteins were modified in a dynamic fashion by palmitate, without being farnesylated; bound to membranes modestly (40% as well as native Ha-Ras); and retained appropriate GTP binding properties. Ext61L caused potent transformation of NIH 3T3 cells and, unexpectedly, an exaggerated differentiation of PC12 cells. Ext61L with the six lysines but lacking palmitates was inactive. Thus, farnesyl is not needed as a signal for palmitate attachment or removal, and a combination of transient palmitate modification and basic residues can support Ha-Ras membrane binding and two quite different biological functions. The roles of palmitate can therefore be independent of and distinct from those of farnesyl. Reciprocally, if membrane association can be sustained largely through palmitates, farnesyl is freed to interact with other proteins.     

Laser Diode-Pumped Organic Semiconductor Lasers Utilizing Two-Dimensional Photonic Crystal Resonators

Two-dimensional photonic crystal lasers based on the small molecule organic semiconductor tris-(8-hydroxyquinoline) aluminum (Alq ₃) doped with 4-Dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) are optically pumped with a conventional low-cost pulsed (In)GaN laser diode. We compare photonic crystal resonators providing first- and second-order distributed feedback and find threshold values of 1.9 and 3.2kW/cm², respectively. Such inorganic-organic hybrid laser systems open up a way to inexpensive, tunable, and all solid-state lasers in the full visible wavelength range