11 research outputs found
Non-sliced Optical Arbitrary Waveform Measurement (OAWM) Using a Silicon Photonic Receiver Chip
Comb-based optical arbitrary waveform measurement (OAWM) techniques can
overcome the bandwidth limitations of conventional coherent detection schemes
and may have disruptive impact on a wide range of scientific and industrial
applications. Over the previous years, different OAWM schemes have been
demonstrated, showing the performance and the application potential of the
concept in laboratory experiments. However, these demonstrations still relied
on discrete fiber-optic components or on combinations of discrete coherent
receivers with integrated optical slicing filters that require complex tuning
procedures to achieve the desired performance. In this paper, we demonstrate
the first wavelength-agnostic OAWM front-end that is integrated on a compact
silicon photonic chip and that neither requires slicing filters nor active
controls. Our OAWM system comprises four IQ receivers, which are accurately
calibrated using a femtosecond mode-locked laser and which offer a total
acquisition bandwidth of 170 GHz. Using sinusoidal test signals, we measure a
signal-to-noise-and-distortion ratio (SINAD) of 30 dB for the reconstructed
signal, which corresponds to an effective number of bits (ENOB) of 4.7 bit,
where the underlying electronic analog-to-digital converters (ADC) turn out to
be the main limitation. The performance of the OAWM system is further
demonstrated by receiving 64QAM data signals at symbol rates of up to 100 GBd,
achieving constellation signal-to-noise ratios (CSNR) that are on par with
those obtained for conventional coherent receivers. In a theoretical
scalability analysis, we show that increasing the channel count of non-sliced
OAWM systems can improve both the acquisition bandwidth and the signal quality.
We believe that our work represents a key step towards out-of-lab use of highly
compact OAWM systems that rely on chip-scale integrated optical front-ends
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
Slice-Less Optical Arbitrary Waveform Measurement (OAWM) in a Bandwidth of More than 600 GHz Using Soliton Microcombs
We propose and demonstrate a novel scheme for optical arbitrary waveform
measurement (OAWM) that exploits chip-scale Kerr soliton combs as highly
scalable multiwavelength local oscillators (LO) for ultra-broadband full-field
waveform acquisition. In contrast to earlier concepts, our approach does not
require any optical slicing filters and thus lends itself to efficient
implementation on state-of-the-art high-index-contrast integration platforms
such as silicon photonics. The scheme allows to measure truly arbitrary
waveforms with high accuracy, based on a dedicated system model which is
calibrated by means of a femtosecond laser with known pulse shape. We
demonstrated the viability of the approach in a proof-of-concept experiment by
capturing an optical waveform that contains multiple 16 QAM and 64 QAM
wavelength-division multiplexed (WDM) data signals with symbol rates of up to
80 GBd, reaching overall line rates of up to 1.92 Tbit/s within an optical
acquisition bandwidth of 610 GHz. To the best of our knowledge, this is the
highest bandwidth that has so far been demonstrated in an OAWM experiment
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
Primary pleomorphic liposarcoma of fallopian tube with recurrence: a case report and review of the literature
Liposarcoma, which develops in adipose tissue, is one of the most common soft tissue sarcomas. It appears mostly in the lower limbs, particularly in the thigh and limb girdles, followed by the upper extremities, thoracoabdominal wall, and the internal trunk and retroperitoneum. Pleomorphic liposarcoma (PLS), a rare subtype of liposarcoma is considered a highgrade malignancy
Large Brunner’s gland adenoma of the duodenum for almost 10 years
Brunner’s gland adenoma is a rare benign tumor arising from
Brunner’s glands. It is mostly small in size, and patients with this tumor
are asymptomatic
Perovskite solar cells with embedded homojunction via nonuniform metal ion doping
A long photoluminescence decay lifetime has been regarded as a generic indication of long charge carrier recombination lifetime in semiconductors such as metal halide perovskites (MHPs), which have shown tremendous success in solar cells. Here, we report that MHP polycrystalline films with extrinsic metal ions have a very long charge recombination lifetime, but a much shorter photoluminescence decay lifetime, and this huge difference can be explained by a model of lateral homojunction within each individual grain. The lateral homojunction is formed due to the doping along grain boundaries by metal ions, and then verified by nanoscale potential mapping and transient photo-response mapping. The built-in electric field within each grain reduces the recombination of free charge carriers within the perovskite grain and along grain boundaries, while the free electrons and holes are collected to cathode and anode through the grain boundaries and grain interiors, respectively. Then, the efficiencies of MHP polycrystalline solar cells are increased.ChemE/Opto-electronic Material