RF photonic instantaneous frequency measurement using DC photo-detection

A microwave photonic instantaneous frequency measurement (IFM) system based on a photonic transversal approach and DC-detection is proposed and practically demonstrated. This system is able to measure the RF frequency and power level independently

Two output RF hybrid coupler using photonic transversal approach

A novel technique to implement a two output broad band RF hybrid coupler based on transversal signal processing is proposed and practically demonstrated. It features broadband frequency range, stable phase difference at outputs, 50 ohm input/output impedance, and low noise characteristics. This technique is suitable for non-coherent optic implementation

Numerical studies of the Lagrangian approach for reconstruction of the conductivity in a waveguide

We consider an inverse problem of reconstructing the conductivity function in a hyperbolic equation using single space-time domain noisy observations of the solution on the backscattering boundary of the computational domain. We formulate our inverse problem as an optimization problem and use Lagrangian approach to minimize the corresponding Tikhonov functional. We present a theorem of a local strong convexity of our functional and derive error estimates between computed and regularized as well as exact solutions of this functional, correspondingly. In numerical simulations we apply domain decomposition finite element-finite difference method for minimization of the Lagrangian. Our computational study shows efficiency of the proposed method in the reconstruction of the conductivity function in three dimensions

Reduced cost photonic instantaneous frequency measurement system

A wideband photonic instantaneous frequency measurement system is proposed and practically demonstrated. This system employs only a low-frequency inexpensive photodetector and thus the system cost is reduced

Amplitude independent RF instantaneous frequency measurement system using photonic Hilbert transform

A photonic instantaneous frequency measurement system capable of measuring both RF frequency and power simultaneously, is conceived and practically demonstrated. This system employs an RF photonic Hilbert transformer together with low-cost, low-frequency photo-detectors to obtain two orthogonal DC measurements. This system exhibits a frequency range of 1-10 GHz. Wider frequency range can be achieved through integration

Wideband RF photonic in-phase and quadrature-phase generation

A photonic implementation of a practical broadband RF Hilbert transformer is demonstrated by using a four-tap transversal system. An almost ideal 90° phase shift with less than 3 dB of amplitude ripple has been achieved from 2.4 to 17.6 GHz. An efficient method to realize both transformed (quadrature-phase) and reference (in-phase) signal has been achieved by using a coarse wavelength division multiplexing coupler. Extension of the transformer bandwidth and further improvements of its implementation are discussed

Photonic instantaneous frequency measurement using non-linear optical mixing

In this paper we propose and demonstrate a photonically implemented instantaneous frequency measurement system. This system uses two differentially delayed modulated optical carriers that are mixed using a semiconductor optical amplifier. The output of the system includes a DC component that varies as a function of frequency. This can be used for frequency measurement using a low-cost DC photo-detector. Operation is demonstrated from 2-20 GHz

Development of a Mind Map System Integrating Full Moodle Function

An LMS is the most basic infrastructure used in e-learning. Various types of LMSs are used, covering open source and commercial software. Moodle is one of the most widely used LMSs today. Moodle has many features that are educationally useful because of its long history and contributions of community. Moodle’s wide variety of functions are sometimes criticized as being too complicated to use. It is necessary to develop an LMS with various functions inside a simple and user-friendly GUI. In this paper, a Moodle GUI has been improved by mapping the main functions of a Moodle course to OKMindmap, which is an open service that runs on the Web, so that learners and teachers can use LMS services in a simple and convenient way. The developed results are demonstrated by applying actual class scenarios with which course activities, supplementary resources, and additional guide information was successfully integrated in a mind map

Detection of Methyl Radicals in a Flat Flame by Degenerate Four-Wave Mixing

We report the spatially resolved detection of methyl radicals in a methane–air f lat flame, using degenerate four-wave mixing (DFWM). A frequency-tripled dye laser pumped with a frequency-doubled Nd:YAG laser was used to access the Herzberg b1 band of methyl near 216 nm. Using a nearly phase-conjugate geometry, we detected methyl with high spatial resolution [0.2 mm (0.3 mm) vertical (horizontal) and ,6 mm longitudinal] and with good signal-to-noise ratio in a rich sf _ 1.55d flame. Compared with laser absorption spectra, DFWM spectra were much less influenced by a broad featureless background. From the absorption data, we measured the peak methyl concentration to be 650 parts in 106, resulting in an estimated DFWM detection limit of 65 parts in 106.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86762/1/Sick48.pd

Low-cost RF frequency measurement using photonic approach

A technique to implement frequency measurement photonically using only low-cost DC photodetectors is proposed and a proof of concept implementation is practically demonstrated. Techniques to further reduce cost and extend bandwidth are proposed