There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160)  Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.

/pdf/the-observation-of-gravitational-waves-from-a-binary-black-58srpupgg9.pdf

The Observation of Gravitational Waves from a Binary Black Hole Merger

Microwave photonics, which brings together the worlds of radiofrequency engineering and optoelectronics, has attracted great interest from both the research community and the commercial sector over the past 30 years and is set to have a bright future. The technology makes it possible to have functions in microwave systems that are complex or even not directly possible in the radiofrequency domain and also creates new opportunities for telecommunication networks. Here we introduce the technology to the photonics community and summarize recent research and important applications.

Microwave photonics combines two worlds

An overview of analog microwave photonics will be presented. The performance requirements for externally-modulated analog microwave photonic links will be reviewed with specific emphasis placed on modulator efficiency, laser noise, detected photocurrent, and link linearity.

http://ieeexplore.ieee.org/iel5/6387506/6403300/06403360.pdf

Microwave photonics

A Mott diode structure is proposed for use as an optically pumped electronic mixer. Under forward bias, the structure should combine good responsivity with a nonlinear I/V characteristic for mixing. Predictions from an accurate mixer analysis indicate that efficient frequency conversion should be achievable at microwave frequencies.

Novel optically pumped electronic mixer using a mott diode structure

We have fabricated modulator/detectors with modulation bandwidths exceeding 15 GHz, the highest yet reported for InGaAsP/InGaAsP MQW AFPMDs. Wavelength dependence of the modulated output power at m ...

High-speed 1.56 μm asymmetric Fabry-Perot modulator/detector (AFPMD) for radio-over-fibre applications

In this paper, we report the first fully bidirectional wireless data transmission of IEEE802.11a Wireless Local Area (WLAN) signals over fibre using uncooled directly modulated lasers thus providing a low cost solution. A successful connection of IEEE802.11a was established between a mobile unit and the remote base station (BS) which in turn was connected via an optical fibre to the wireless access point. A maximum data throughput of 20 Mbps and 18 Mbps was achieved at a 10 m separation distance between the mobile unit and the BS antenna in the uplink and downlink directions respectively. Results are also presented for the data throughput performance of the system with varying free space distance and the measured average throughput in both transmission directions.

Wireless data transmission of IEEE802.11a signals over fibre using low cost uncooled directly modulated lasers

Summary form only given. This is, to our knowledge, the first report of both all-optical wavelength conversion in an Fabry Perot saturable absorber (SA) incorporating an ion-bombarded MQW SA, and fast recovery through ion-bombardment in an InGaAsP/InGaAsP MQW. The measured contrast ratio and recovery time of our device, 10 dB and 4.1 ps respectively demonstrate its potential for 40 Gbps WDM system applications.

Wavelength conversion of 1.53 micron picosecond pulses in an ion-implanted multiple quantum well all-optical switch

This paper demonstrates a novel digital radio over fibre (DRoF) architecture that is able to transport multiple compressed digitised RF services using both optical fibre and wireless millimetre wave (mmW) links. This solution has advantages as a cost effective indoor wireless infrastructure where flexible transmission schemes are required. Experimental results indicate wide RF dynamic range for two LTE services transmitted simultaneously, showing its capability for creating a neutral-host radio access network (RAN) with good spectral efficiency and cost effectiveness.

/pdf/multi-service-digital-radio-over-fibre-system-with-3aruab8q54.pdf

Alwyn J. Seeds

Papers

Novel optically pumped electronic mixer using a mott diode structure

High-speed 1.56 μm asymmetric Fabry-Perot modulator/detector (AFPMD) for radio-over-fibre applications

Wireless data transmission of IEEE802.11a signals over fibre using low cost uncooled directly modulated lasers

Wavelength conversion of 1.53 micron picosecond pulses in an ion-implanted multiple quantum well all-optical switch

Multi-service Digital Radio over Fibre System with Millimetre Wave Bridging