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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.

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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems

Information Theory and Reliable Communication

Influence of time delay in a balanced optical phase-locked loops (OPLL) with a proportional integrator (Pl) filter is investigated using a delayed differential equation (DDE) is investigated. The limitations, which a time delay imposes on the Pl filter bandwidth, at increasing values of loop gain, are investigated by numerical simulations. Furthermore, simple expressions governing the stability properties of the loop, in the presence of time delay, are derived. For this purpose, three standard loop filters are considered: a Pl filter, a low pass (LP) filter and an active lag (AL) filter. The derived expressions are used to perform an optimisation in terms of the selected loop filters.

/pdf/analysis-of-the-effects-of-time-delay-in-clock-recovery-2e7z6llyhv.pdf

Analysis of the effects of time delay in clock recovery circuits based on phase-locked loops

This tutorial will cover recent advances towards the generation of Terabit per second single channel systems using optical time division multiplexing. It will describe key technologies and requirements to such systems and address energy considerations.

Tutorial: Terabit/second OTDM systems

We experimentally demonstrate a 640 Gbit/s all-optical NOT gate for high-speed telecommunication on-off-keying (OOK) data signals. We employ linear optical signal processing based on spectral phase-only (all-pass) optical filtering to perform the target logic NOT operation.

Passive linear-optics 640 Gbit/s logic NOT gate

We propose a scheme for phase regeneration of an optical binary phase shift keying (BPSK) data signal using a Lithium Niobate (LiNbO3) phase modulator. The scheme is based on heterodyne detection of the BPSK data signal with a continuous wave local oscillator (CW-LO). Carrier recovery is then achieved in the electrical domain using a ×2 frequency-multiplier and a narrow-band filtering scheme. Subsequently, a superposition of the recovered carrier and the heterodyne detected data signal is used to modulate the CW-LO in a LiNbO3 phase modulator. The result is a parametric mixing process in the optical domain, leading to a phase-regenerated BPSK data signal by the coherent superposition with a phase-inverted copy. The proposed scheme constitutes a compact and stable setup, where active phase-stabilization of the electrical data- and carrier-paths can potentially be avoided. An analytical derivation of the working principle is provided, using Jacobi–Anger expansions to describe the phase-modulation. A proof-of-principle experiment is carried out, demonstrating regeneration of a 10 Gb/s NRZ-BPSK data signal degraded by a 5-GHz sinusoidal phase-noise tone. In the proof-of-principle demonstration, the decorrelated data- and LO-carriers are derived from the same CW source. A preliminary test with separate CW sources for data and LO, but without the required electrical narrow-band carrier filtering, is also included. Finally, numerical simulations of the regenerator performance in the presence of wideband phase- and amplitude-noise are performed.

Phase Regeneration of a BPSK Data Signal Using a Lithium Niobate Phase Modulator

The impact of gating timing jitter on a 160 Gb/s demultiplexer is investigated by using two pulse sources with different timing jitter properties. It is found that jitter in the range 20 kHz-10 MHz is essential to minimize.

Leif Katsuo Oxenløwe

Papers

Analysis of the effects of time delay in clock recovery circuits based on phase-locked loops

Tutorial: Terabit/second OTDM systems

Passive linear-optics 640 Gbit/s logic NOT gate

Phase Regeneration of a BPSK Data Signal Using a Lithium Niobate Phase Modulator

The impact of gating timing jitter on a 160 Gb/s demultiplexer