Resistive loop directional coupler calibration
Resistive loop directional coupler calibration
CALIBRATION↗
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Directional coupler for optical waveguides
Feasibility study of transmitting optical energy in single mode through photonic waveguides results in a conceptual directional coupler consisting of two types of optical waveguides /a stratified /core/ dielectric and a mirror wall/. Waveguide medium analysis produced formulation of mode cutoff conditions, field distributions, and propagation characteristics.
Schineller, E. R.↗
Frequency selective coupler for integrated optics systems.
A frequency selective coupler which consists of two thin film waveguides imbedded in a periodic medium is studied using the Brillouin diagram. Detailed results for the relative bandwidth and the coupling factor are plotted as a function of normalized frequency for a representative case.
Elachi, C.↗
Rotating optical coupler for signal transmission
Optical coupler using Dove prism assembly to form stationary image of rotating object, transmits data across rotating interface without sliprings or other mechanical contacts. Device can handle many high-bit-rate data channels.
Ivie, C. V.↗
Circuit Methods for VLF Antenna Couplers
The limitations of different E-field antenna coupler or preamplifier circuits are presented. All circuits were evaluated using actual Loran or Omega signals. Electric field whip or wire antennas are the simplest types which can be used for reception of VLF signals in the 10 to 100 kHz range. JFET or MOSFET transistors provide impedance transformation and some voltage gain in simple circuits where the power for operating the preamplifier uses the same coaxial cable that feeds the signal back to the receiver. The circuit techniques provide useful alternative methods for Loran-Omega receiver system designers.
Burhans, R. W.↗
Dual coupler configuration at DSS 14 for the Voyager era
A description is given of the dual coupler configuration which was installed at DSS 14 for station delay calibrations during the Voyager era. The Z correction values determined for these new and previous configurations are presented.
Otoshi, T. Y.↗
Coupler for remote manipulators
Reliable, low-cost coupler alines and grasps moving and rotating objects. Coupling mechanism may be used in handling of radio-active materials or in underwater explorations and other remote manipulators.
Rudmann, A. A.↗
Determining the refractive index and thickness of thin films from prism coupler measurements
A simple method of determining thin film parameters from mode indices measured using a prism coupler is described. The problem is reduced to doing two least squares straight line fits through measured mode indices vs effective mode number. The slope and y intercept of the line are simply related to the thickness and refractive index of film, respectively. The approach takes into account the correlation between as well as the uncertainty in the individual measurements from all sources of error to give precise error tolerances on the best fit values. Due to the precision of the tolerances, anisotropic films can be identified and characterized.
Kirsch, S. T.↗
Fabricating Grating Couplers on Optical Fibers
Microscopic corrugations form on fiber surfaces. Grating couplers couple signals into and out of single-mode optical waveguides without requiring precise alignment of components, although in-service efficiency has yet to be verified.
Chubb, C. R.↗
Optical-Fiber-to-Channel-Waveguide Coupler
Holding device made by etching V-shaped grooves in silicon in coupler close tolerances are achieved for high-efficiency coupling between optical fibers with core diameter of 5 um and 110 um in cross section. Fibers are held in V-shaped grooves on silicon chips.
Ramer, G. O.↗
Plasmon device design: Conversion from surface to junction plasmons with grating-couplers
Scaling calculations and numerical studies are used to show that grating couplers provide effective energy transfer between surface plasmons and slower modes localized in the tunnel diodes. Within first order perturbation theory in grating amplitude, 90% efficiency energy transfer occurs within micrometers for realistic structures and materials parameters. Scaling laws are derived. Seventy to 90% of the electromagnetic field energy is concentrated in the oxide layer of an MOM diode after the energy is distributed by longer range modes that have less than 0.1% overlap with the tunneling region. The mode conversion allows the requirements separation for energy transport and power production by inelastic tunneling.
Anderson, L. M.↗
Polarization preserving single mode fiber optic coupler
A technique is described for fabrication of etched single mode fiber optical waveguide couplers which preserve the polarization state to within 0.0001. The coupling ratio is tunable over a broad range (0-9 percent) during fabrication. Back-coupling is less than 0.001, insertion loss is less than 1.5 dB, and coupling ratio thermal coefficient is about 1 percent per degree C.
Nelson, M. D.↗
Nonlinear effects in coplanar GaAs/InGaAs strained-layer superlattice directional couplers
The performance characteristics of InGaAs/GaAs strained-layer superlattice coplanar ridge-type directional couplers realized by molecular beam epitaxy are reported. The measured power transfer characteristics with 1.15 micron incident photoexcitation demonstrate nonlinear coupling due to absorption associated with the tails of the excitonic resonances in the quantum wells. From a theoretical fit of the measured data, the nonlinear refractive index coefficient, n2, of the multiquantum well is found to be 2.25 x 10 to the -7th sq cm/W. This agrees very well with a value of n2 = 1.9 x 10 to the-7th sq cm/W obtained independently on the same material from interferometric measurents.
Das, Utpal↗
Study of optical output couplers for submillimeter wavelength backward-wave oscillators (BWO's)
Several scaled experiments of optical output couplers for submillimeter backward-wave oscillators (BWOs). Various designs of planar antennas (Vivaldi horns) lens-feed systems (hyperhemispherical lens) were constructed and tested between 20 and 100 GHz using a spectrum analyzer. The lens system was also tested at 337 GHz using a CO2 pumped FIR laser. It is found that Vivaldi horns have unsatisfactory resonances, perhaps because the horns studied were relatively short. Several techniques to maximize and flatten the frequency response of these horns are presented. The results suggest that alternate coupling schemes are superior to Vivaldi horns.
Cook, Jerry D.↗
Shaft Adapter For Data Coupler
Shaft adapter developed to provide means for securing Acurex 1200B universal data coupler to rotating instrumented shaft. Consists of two major parts: shaft sleeve and shaft clamp. Provides for accurate measurements of stresses and strains in shaft.
Elliott, James R.↗
Electro-Optic Modulator Based on Organic Planar Waveguide Integrated with Prism Coupler
The objectives of the project, as they were formulated in the proposal, are the following: (1) Design and development of novel electro-optic modulator using single crystalline film of highly efficient electro-optic organic material integrated with prism coupler; (2) Experimental characterization of the figures-of-merit of the modulator. It is expected to perform with an extinction ratio of 10 dB at a driving signal of 5 V; (3) Conclusions on feasibility of the modulator as an element of data communication systems of future generations. The accomplishments of the project are the following: (1) The design of the electro-optic modulator based on a single crystalline film of organic material NPP has been explored; (2) The evaluation of the figures-of-merit of the electro-optic modulator has been performed; (3) Based on the results of characterization of the figures-of-merit, the conclusion was made that the modulator based on a thin film of NPP is feasible and has a great potential of being used in optic communication with a modulation bandwidth of up to 100 GHz and a driving voltage of the order of 3 to 5 V.
Sarkisov, Sergey S.↗
Calibration of Passive Microwave Polarimeters that Use Hybrid Coupler-Based Correlators
Four calibration algorithms are studied for microwave polarimeters that use hybrid coupler-based correlators: 1) conventional two-look of hot and cold sources, 2) three looks of hot and cold source combinations, 3) two-look with correlated source, and 4) four-look combining methods 2 and 3. The systematic errors are found to depend on the polarimeter component parameters and accuracy of calibration noise temperatures. A case study radiometer in four different remote sensing scenarios was considered in light of these results. Applications for Ocean surface salinity, Ocean surface winds, and soil moisture were found to be sensitive to different systematic errors. Finally, a standard uncertainty analysis was performed on the four-look calibration algorithm, which was found to be most sensitive to the correlated calibration source.
Piepmeier, J. R.↗
Y-branch optical coupler monolithically integrated with DFB quantum cascade lasers
Y-branch optical coupler monolithically integrated with two DFB Quantum Cascade Laser has been demonstrated and studied.
Mid-IR lasers↗