18 research outputs found
Increasing the Field-of-View Radiation Efficiency of Optical Phased Antenna Arrays
Silicon photonics in conjunction with complementary metal-oxide-semiconductor
(CMOS) fabrication has greatly enhanced the development of integrated optical
phased arrays. This facilitates a dynamic control of light in a compact form
factor that enables the synthesis of arbitrary complex wavefronts in the
infrared spectrum. We numerically demonstrate a large-scale two dimensional
silicon-based optical phased array (OPA) composed of nanoantennas with circular
gratings that are balanced in power and aligned in phase, required for
producing elegant radiation patterns in the far field. For a wavelength of
1.55, we optmize two antennas for the OPA exhibting an upward radiation
efficiency as high as 90%, with almost 6.8% of optical power concentrated in
the field of view. Additionally, we believe that the proposed OPAs can be
easily fabricated and would have the ability of generating complex holographic
images, rendering them an attractive candidate for a wide range of applications
like LiDAR sensors, optical trapping, optogenetic stimulation and
augmented-reality displays
Real100G.COM
In 2012 a group of researchers proposed a basic research initiative to the German Research Foundation (DFG) as a special priority project (SPP) with the name: Wireless 100 Gbps and beyond. The main goal of this initiative was the investigation of architectures, technologies and methods to go well beyond the state of the art. The target of 100 Gbps was set far away from the (at that time) achievable 1 Gbps such that it was not possible to achieve promising results just by tuning some parameters. We wanted to find breakthrough solutions. When we started the work on the proposal we discussed the challenges to be addressed in order to advancing the wireless communication speed significantly. Having the fundamental Shannon boundary in mind we discussed how to achieve the 100 Gbps speed.Angesichts der rapiden Entwicklung der Funkkommunikation hat die Deutsche Forschungsgemeinschaft im Jahr 2012 ein Schwerpunktprogramm mit dem Titel "Wireless 100 Gbps and beyound" (dt.: Drahtloskommunikation mit 100 Gbps und mehr) gestartet. Diese Initiative zielte auf neue Lösungen, Methoden und neues Wissen zur Lösung des Problems des kontinuierlichen Bedarfs an immer höheren Datenraten im Bereich der Funkkommunikation. Eine international besetze Jury hat etliche ProjektvorschlĂ€ge evaluiert, aus denen 11 Projekte ausgewĂ€hlt und ĂŒber zweimal 3 Jahre von Mitte 2013 bis Mitte 2019 gefördert wurden. Das vorliegende Buch versammelt die AnsĂ€tze, Architekturen und Erkenntnisse der Projekte. Es ĂŒberspannt einen breiten Themenbereich, angefangen mit speziellen Fragen der physikalischen Ăbertragung, des Antennendesigns und der HF-Eingangs-Architekturen fĂŒr unterschiedliche Frequenzbereiche bis 240 GHz. DarĂŒber hinaus beschreibt das Buch AnsĂ€tze fĂŒr Ultra-Hochgeschwindigkeits-Funksysteme, deren Basisbandverarbeitung, Kodierung sowie mögliche Umsetzungen. Nicht zuletzt wurden auch Fragen des Protokolldesigns behandelt, um eine enge Integration in moderne Computersysteme zu erleichtern
Mode-locked laser timing jitter limitation in optically enabled, spectrally sliced ADCs
Novel analog-to-digital converter (ADC) architectures are motivated by the
demand for rising sampling rates and effective number of bits (ENOB). The main
limitation on ENOB in purely electrical ADCs lies in the relatively high jitter
of oscillators, in the order of a few tens of fs for state-of-the-art
components. When compared to the extremely low jitter obtained with
best-in-class Ti:sapphire mode-locked lasers (MLL), in the attosecond range, it
is apparent that a mixed electrical-optical architecture could significantly
improve the converters' ENOB. We model and analyze the ENOB limitations arising
from optical sources in optically enabled, spectrally sliced ADCs, after
discussing the system architecture and implementation details. The phase noise
of the optical carrier, serving for electro-optic signal transduction, is shown
not to propagate to the reconstructed digitized signal and therefore not to
represent a fundamental limit. The optical phase noise of the MLL used to
generate reference tones for individual slices also does not fundamentally
impact the converted signal, so long as it remains correlated among all the
comb lines. On the other hand, the timing jitter of the MLL, as also reflected
in its RF linewidth, is fundamentally limiting the ADC performance, since it is
directly mapped as jitter to the converted signal. The hybrid nature of a
photonically enabled, spectrally sliced ADC implies the utilization of a number
of reduced bandwidth electrical ADCs to convert parallel slices, resulting in
the propagation of jitter from the electrical oscillator supplying their clock.
Due to the reduced sampling rate of the electrical ADCs, as compared to the
overall system, the overall noise performance of the presented architecture is
substantially improved with respect to a fully electrical ADC
Optically Enabled ADCs and Application to Optical Communications
Electrical-optical signal processing has been shown to be a promising path to overcome the limitations of state-of-the-art all-electrical data converters. In addition to ultra-broadband signal processing, it allows leveraging ultra-low jitter mode-locked lasers and thus increasing the aperture jitter limited effective number of bits at high analog signal frequencies. In this paper, we review our recent progress towards optically enabled time- and frequency-interleaved analog-to-digital converters, as well as their monolithic integration in electronic-photonic integrated circuits. For signal frequencies up to 65 GHz, an optoelectronic track-and-hold amplifier based on the source-emitter-follower architecture is shown as a power efficient approach in optically enabled BiCMOS technology. At higher signal frequencies, integrated photonic filters enable signal slicing in the frequency domain and further scaling of the conversion bandwidth, with the reconstruction of a 140 GHz optical signal being shown. We further show how such optically enabled data converter architectures can be applied to a nonlinear Fourier transform based integrated transceiver in particular and discuss their applicability to broadband optical links in general
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[no abstract available
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Optically clocked switched-emitter-follower THA in a photonic SiGe BiCMOS technology
In this paper a novel opto-electronic Track-and-Hold Amplifier (OE-THA) is presented.The OE-THA can be used as a sampler in a photonic analog-to-digital-converter (ADC). Itis fabricated in a silicon photonic 250 nm SiGe BiCMOS technology to allow for monolithicintegration of photonic and electronic components. The OE-THA chip exhibits a small signalbandwidth of over 65 GHz, a total harmonic distortion below â34 dB up to 75 GHz and asignal-to-noise and distortion ratio (SINAD) of over 35 dB (5.5 effective bits, ENOB) up to45 GHz. The measured resolution bandwidth products result in a corresponding equivalent jitterof below 80 fs rms from 20 to 70 GHz. The best equivalent jitter is achieved at 41 GHz with avalue of 55.8 fs rms. This is enabled by using a low-jitter optical pulse train, generated by aMode-Locked-Laser (MLL), as an optical sampling clock. The circuit integrates all optical andelectronic components besides the MLL. It draws 110 mA operated from a supply voltage ofâ4.6 V and occupies a silicon area of only 0.59 mm
Increasing the Field-of-View Radiation Efficiency of Optical Phased Antenna Arrays
<p>Numerical optimization of antenna elements to be employed in a large-scale two dimensional silicon-based optical phased array.</p><p>Financial support from the German Research Foundation (Deutsche Forschungsgemeinschaft DFG, project 231447078âTRR 142, subproject B06 & C05) and Ministry of Culture and Science of the state of North Rhine-Westphalia (PhoQC project) is gratefully acknowledged.</p>