The agnostic sampling transceiver

Increasing capacity demands in the access networks require inventive concepts for the transmission and distribution of digital as well as analog signals over the same network. Here a new transceiver system, which is completely agnostic for the signals to be transmitted is presented. Nyquist sampling and time multiplexing of N phase and intensity modulated digital and analog channels with one single modulator, as well as the transmission and demultiplexing with another modulator have been demonstrated. The aggregate symbol rate corresponds to the modulator bandwidth and can be further increased by a modification of the setup. No high-speed electronic signal processing or high bandwidth photonics is required. Apart from its simplicity and the possibility to process high bandwidth signals with low bandwidth electronics and photonics, the method has the potential to be easily integrated into any platform and thus, might be a solution for the increasing data rates in future access networks

Orthogonal Full-Field Optical Sampling

Sampling is the first step to convert analogue into digital signals and one of the basic concepts for information handling. All practical sampling systems, however, are accompanied with errors. Bandwidth-limited signals can be seen as a superposition of time-shifted sinc pulses, weighted with the sampling values. Thus, due to orthogonality, bandlimited signals can be perfectly sampled by a corresponding sinc pulse with the correct time shift. But, sinc pulses are just a mathematical construct. Sinc pulse sequences, instead, can simply be generated by a rectangular, phase-locked frequency comb. For a high repetition-time to pulsewidth ratio, or a low duty cycle, the pulses of such a sequence come close to single sinc pulses, and thus, the sampling with them might lead to an almost ideal sampling. Here, we present the full-field optical sampling with a repetition-time to pulsewidth ratio of up to 153, or a duty cycle of around 0.65%. Since it enables amplitude and phase sampling, ultrahigh sampling rates should be possible

Orthogonal Sampling based Broad-Band Signal Generation with Low-Bandwidth Electronics

High-bandwidth signals are needed in many applications like radar, sensing, measurement and communications. Especially in optical networks, the sampling rate and analog bandwidth of digital-to-analog converters (DACs) is a bottleneck for further increasing data rates. To circumvent the sampling rate and bandwidth problem of electronic DACs, we demonstrate the generation of wide-band signals with low-bandwidth electronics. This generation is based on orthogonal sampling with sinc-pulse sequences in N parallel branches. The method not only reduces the sampling rate and bandwidth, at the same time the effective number of bits (ENOB) is improved, dramatically reducing the requirements on the electronic signal processing. In proof of concept experiments the generation of analog signals, as well as Nyquist shaped and normal data will be shown. In simulations we investigate the performance of 60 GHz data generation by 20 and 12 GHz electronics. The method can easily be integrated together with already existing electronic DAC designs and would be of great interest for all high-bandwidth applications

High-Bandwidth Arbitrary Signal Detection Using Low-Speed Electronics

The growing demand for bandwidth and energy efficiency requires new solutions for signal detection and processing. We demonstrate a concept for high-bandwidth signal detection with low-speed photodetectors and electronics. The method is based on the parallel optical sampling of a high-bandwidth signal with sinc-pulse sequences provided by a Mach-Zehnder modulator. For the electronic detection and processing this parallel sampling enables to divide the high-bandwidth optical signal with the bandwidth B into N electrical signals with the baseband bandwidth of B/(2N) . In proof-of-concept experiments with N=3 , we present the detection of 24 GHz optical signals by detectors with a bandwidth of only 4 GHz. For ideal components, the sampling and bandwidth down-conversion does not add an excess error to the signals and even for the non-ideal components of our proof-of-concept setup, it is below 1%. Thus, the rms error for the measurement of the 24 GHz signal was reduced by a factor of about 3.4 and the effective number of bits were increased by 1.8

Low-Bandwidth Photonics-Assisted Receiver for Broad-Bandwidth Wireless Signals

This paper introduces a photonics-assisted receiver that enables the reception of high-bandwidth wireless signals with low-bandwidth electronics. The receiver down-converts the input signal into parallel low-bandwidth sub-signals, employing photonics-based orthogonal sampling. This sampling is based on a multiplication and not switching, so, it does not introduce additional aperture jitter. Therefore, the photonics-assisted analog-to-digital converter (ADC) converts the wireless signal with a higher signal-to-noise-and-distortion ratio (SINAD), which improves the Q-factor for the detection. This Q-factor improvement is especially high, when the orthogonal sampling is carried out with low-jitter oscillators. Compared to the direct detection with 30 GHz, the simulation demonstrates a 2.2 dB Q-factor enhancement for the detection of a 30 GHz signal, with 10 GHz electronics. The same improvement is revealed in the experiment for the detection of 12 GHz signals with 4 GHz electronics

Filterless and Compact ANy-WDM Transmission System Based on Cascaded Ring Modulators

To cope with the exponential increase in internet services and corresponding data traffic, especially data centers and access networks require new high data rate transmission methods with low cost, very small package and low energy consumption. In this paper, we demonstrate a filterless, agnostic Nyquist wavelength division multiplexing (ANy-WDM) transmission system based on cascaded ring modulators and a comb source. The single ring modulator acts as a filter, filtering one of the n WDM lines, generated by the comb. The same ring modulator modulates k time division multiplexed (TDM) channels on the single wavelength. Since each WDM channel, consisting of k time domain channels, has a rectangular bandwidth, the aggregated symbol rate of the superchannel modulated by this system corresponds to the optical bandwidth of all n WDM channels together. The approach is very simple and compact. Since no optical filters, delay lines or other special photonics or high bandwidth electronics is needed, an integration into any photonics platform is straightforward. Thus, the proposed method might enable very compact, ultra-high data rate transmission devices for future data centers and access networks

Orthogonal Sampling-Based Broad-Band Signal Generation With Low-Bandwidth Electronics

High-bandwidth signals are needed in many applications like radar, sensing, measurement and communications. Especially in optical networks, the sampling rate and analog bandwidth of digital-to-analog converters (DACs) is a bottleneck for further increasing data rates. To circumvent the sampling rate and bandwidth problem of electronic DACs, we demonstrate the generation of wide-band signals with low-bandwidth electronics. This generation is based on orthogonal sampling with sinc-pulse sequences in ${N}$ parallel branches. The method not only reduces the sampling rate and bandwidth, at the same time the effective number of bits (ENOB) is improved, dramatically reducing the requirements on the electronic signal processing. In proof of concept experiments the generation of analog signals, as well as Nyquist shaped and normal data will be shown. In simulations we investigate the performance of 60 GHz data generation by 20 and 12 GHz electronics. The method can easily be integrated together with already existing electronic DAC designs and would be of great interest for all high-bandwidth applications

Reconfigurable and real-time high-bandwidth Nyquist signal detection with low-bandwidth in silicon photonics

We demonstrate for the first time, to the best of our knowledge, reconfigurable and real-time orthogonal time-domain detection of a high-bandwidth Nyquist signal with a low-bandwidth silicon photonics Mach-Zehnder modulator based receiver. As the Nyquist signal has a rectangular bandwidth, it can be multiplexed in the wavelength domain without any guardband as a part of a Nyquist-WDM superchannel. These superchannels can be additionally multiplexed in space and polarization. Thus, the presented demonstration can open a new possibility for the detection of multidimensional parallel data signals with silicon photonics. No external pulse source is needed for the receiver, and frequency-time coherence is used to sample the incoming Nyquist signal with orthogonal sinc-shaped Nyquist pulse sequences. All parameters are completely tunable in the electrical domain. The feasibility of the scheme is demonstrated through a proof-of-concept experiment over the entire C-band (1530 nm-1560 nm), employing a 24 Gbaud Nyquist QPSK signal due to experimental constraints on the transmitter side electronics. However, the silicon Mach-Zehnder modulator with a 3-dB bandwidth of only 16 GHz can process Nyquist signals of 90 GHz optical bandwidth, suggesting a possibility to detect symbol rates up to 90 GBd in an integrated Nyquist receiver

Early results of first versus second generation Amplatzer occluders for left atrial appendage closure in patients with atrial fibrillation

Background: Transcatheter left atrial appendage (LAA) occlusion has been proven to be an effective treatment for stroke prophylaxis in patients with atrial fibrillation. For this purpose, the Amplatzer cardiac plug (ACP) was introduced. Its second generation, the Amulet, was developed for easier delivery, better coverage, and reduction of complications. Aim: To investigate the safety and efficacy of first generation versus second generation Amplatzer occluders for LAA occlusion. Methods: Retrospective analysis of prospectively collected data from the LAA occlusion registries of the Bern and Zurich university hospitals. Comparison of the last consecutive 50 ACP cases versus the first consecutive 50 Amulet cases in patients with non-valvular atrial fibrillation. For safety, a periprocedural combined endpoint, which is composed of death, stroke, cardiac tamponade, and bailout by surgery was predefined. For efficacy, the endpoint was procedural success. Results: There were no differences between the two groups in baseline characteristics. The percentage of associated interventions during LAA occlusion was high in (78% with ACP vs. 70% with Amulet p=ns). Procedural success was similar in both groups (98 vs. 94%, p=0.61). The combined safety endpoint for severe adverse events was reached by a similar rate of patients in both groups (6 vs. 8%, p=0.7). Overall complication rate was insignificantly higher in the ACP group, which was mainly driven by clinically irrelevant pericardial effusions (24 vs. 14%, p=0.31). Death, stroke, or tamponade were similar between the groups (0 vs. 2%, 0 vs. 0%, or 6 vs. 6%, p=ns). Conclusion: Transcatheter LAA occlusion for stroke prophylaxis in patients with atrial fibrillation can be performed with similarly high success rates with first and second generations of Amplatzer occluders. According to this early experience, the Amulet has failed to improve results of LAA occlusion. The risk for major procedural adverse events is acceptable but has to be taken into account when selecting patients for LAA occlusion, a preventive procedure