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

Optical delivery of modulated millimetre-wave signals using free-running laser heteroyne with frequency drift cancellation

In this paper an optical frequency synthesis technique using optical injection phase-locked loop is discussed. An optical frequency comb generator produces a complete set of channel frequencies is extracted from the comb spectrum using an active filtering arrangement, based on the combined use of injection locking and phase locking in an optical injection phase lock loop (OIPLL). This approach eliminates the wide bandwidth, short (<1 ns) loop propagation delay design constraints of conventional optical phase lock loops for use with non line-narrowed semiconductor lasers.

Optical frequency synthesis for high spectral efficiency WDM transmission

This dataset contains experimental data presented in the paper titled 'Generation of continuous wave terahertz frequency radiation from MOCVD grown Fe-doped InGaAs and InGaAsP'. The IV characteristics, THz signal amplitudes, bias and optical power dependence of the different InGaAs and InGaAsP wafers are given.

Generation of continuous wave terahertz frequency radiation from MOCVD grown Fe-doped InGaAs and InGaAsP

https://doi.org/10.1016/j.jlumin.2023.119799

Surface/interface engineering of InAs quantum dot edge-emitting diodes toward III-V/SiN photonic integration

In this Letter, we present long-wavelength microdisk lasers based on five stacks of self-assembled InAs/InAlGaAs quantum dots as the active medium, which were grown on InP (001) substrate by solid-source molecular beam epitaxy. The 8.4- μm-diameter quantum dot microdisk laser is operated at room temperature under pulsed optically pumping conditions. Multi-wavelength lasing emissions at ∼1.6  μm were achieved with a low lasing threshold of 30  μW and a quality factor of ∼1336. The lasing behavior was verified by the “ S” shape L– L curve, linewidth narrowing effect, and strong speckle patterns of the collected near field intensity profile. The demonstrated long-wavelength lasers with low threshold and ultracompact footprint can find potential applications in integrated gas detection and highly localized label-free biological and biochemical sensing.

Alwyn J. Seeds

Papers

Optical delivery of modulated millimetre-wave signals using free-running laser heteroyne with frequency drift cancellation

Optical frequency synthesis for high spectral efficiency WDM transmission

Generation of continuous wave terahertz frequency radiation from MOCVD grown Fe-doped InGaAs and InGaAsP

Surface/interface engineering of InAs quantum dot edge-emitting diodes toward III-V/SiN photonic integration

Long-wavelength InAs/InAlGaAs quantum dot microdisk lasers on InP (001) substrate