ABSTRACT
This Letter reports the electro-optical (EO) effect of Poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofibers colloid in a polymer micro-fluidic EO cell. P3HT nanofibers are high aspect ratio semiconducting nanostructures, and can be collectively aligned by an external alternating electric field. Optical transmission modulated by the electric field is a manifestation of the electro-optical effect due to high inner crystallinity of P3HT nanofibers. According to our results, the degree of alignment reaches a maximum at 0.6 V/µm of electric field strength, implying a big polarizability value due to geometry and electrical properties of P3HT nanofibers. We believe that one-dimensional crystalline organic nanostructures have a large potential in EO devices due to their significant anisotropy, wide variety of properties, low actuation voltages, and opportunity to be tailored via adjustment of the fabrication process.
ABSTRACT
Prospects for a lossless negative dielectric constant material for optical devices are studied. Simulations show that with sufficient gain, a mixture of two semiconductor quantum dots (QDs) can produce an effective dielectric constant that is lossless and negative. This permits, in concept, arbitrarily small scaling of the optical mode volume, a major goal in the field of nanophotonics. The proposed implementation of a lossless negative dielectric constant material based on colloidal QDs opens a tractable path.
Subject(s)
Models, Theoretical , Quantum Dots , Computer Simulation , Electric Impedance , Electrons , Light , Optical DevicesABSTRACT
We report on the first experimental evidence of negative refraction at telecommunication wavelengths by a two-dimensional photonic crystal field. Samples were fabricated by chemically assisted ion beam etching in the InP-based low-index constrast system. Experiments of beam imaging and light collection show light focusing by the photonic crystal field. Finite-difference time-domain simulations confirm that the observed focusing is due to negative refraction in the photonic crystal area.
ABSTRACT
A potentially ultrafast optical analog-to-digital (A/D) converter scheme is proposed and was partly studied experimentally. In the A/D converter scheme the input signal controls the wavelength of a diode laser, whose output beam is incident on a grating. The beam from the grating hits a diffractive optical element in an array. The wavelength determines which element is illuminated. Each element fans out a unique spot-pattern bit code to be read out in parallel by individual detectors. In the experiment all patterns but one from 64 array elements were read out correctly.
ABSTRACT
Analysis of a directional coupler by use of rigorous coupled-mode theory is presented. The coupling process is explained by the mutual coupling of modes of a single waveguide that is due to the presence of the other waveguide. It is explicitly shown by example that the radiation modes that take part in the coupling are just those needed to form the guided modes of the composite double-guide structure.
ABSTRACT
The beam-propagation method is employed to analyze nonlinear directional-coupler operation for various combinations nonlinear materials and initially mismatched guides. A mixed focusing-defocusing configuration is found optimal results.
ABSTRACT
An integrated optics spectrum analyzer based on using the linear electrooptic effect was theoretically investigated earlier. This spectrum analyzer performs Fourier analysis of sampled electronic signals, where each voltage sample is fed to an electrode of a metal electrode array. The electrode array acts as a spatial light modulator, and the diffracted light field is focused on a detector array. The intensity values at the detector elements represent a weighted discrete Fourier transform of the voltage values on the electrodes. The first experimental results to verify the principle of operation of the device are now reported and compared with theory. The prism coupling technique has been used to investigate the influence of an electrode array with voltages on a collimated beam in a LiNbO(3) waveguide. The voltage distributions analyzed correspond to a square wave function and rect functions. The theory has also been extended, and some pertinent signal processing properties of the device are discussed.
ABSTRACT
An extension of the beam propagation method to anisotropic media is presented and the formalism is employed to study several integrated optics devices.
ABSTRACT
An integrated optics spectrum analyzer based on using the linear electrooptic effect is investigated. This spectrum analyzer performs Fourier analysis of sampled electronic signals, where each signal is fed to an electrode of an electrode array. The electrode array acts as a spatial light modulator, and the diffracted light field, representing a weighted discrete Fourier transform (DFT), is focused on a detector array by an integrated transform lens. The theory of operation of the spectrum analyzer is outlined, numerical results relating to this theory are presented, and questions concerning efficiency, dynamic range, design, and implementation are discussed.
