Mikael Mazur

Long-haul coherent communications using microresonator-based frequency combs

Microresonator-based frequency combs are strong contenders as light sources for wavelength-division multiplexing (WDM). Recent experiments have shown the potential of microresonator combs for replacing a multitude of WDM lasers with a single laser-pumped device. Previous demonstrations have however focused on short-distance few-span links reaching an impressive throughput at the expense of transmission distance. Here we report the first long-haul coherent communication demonstration using a microresonator-based comb source. We modulated polarization multiplexed (PM) quadrature phase-shift keying-data onto the comb lines allowing transmission over more than 6300 km in a single-mode fiber. In a second experiment, we reached beyond 700 km with the PM 16 quadrature amplitude modulation format. To the best of our knowledge, these results represent the longest fiber transmission ever achieved using an integrated comb source.

High-order coherent communications using mode-locked dark-pulse Kerr combs from microresonators

Microresonator frequency combs harness the nonlinear Kerr effect in an integrated optical cavity to generate a multitude of phase-locked frequency lines. The line spacing can reach values in the order of 100 GHz, making it an attractive multi-wavelength light source for applications in fiber-optic communications. Depending on the dispersion of the microresonator, different physical dynamics have been observed. A recently discovered comb state corresponds to the formation of mode-locked dark pulses in a normal-dispersion microcavity. Such dark-pulse combs are particularly compelling for advanced coherent communications since they display unusually high power-conversion efficiency. Here, we report the first coherent-transmission experiments using 64-quadrature amplitude modulation encoded onto the frequency lines of a dark-pulse comb. The high conversion efficiency of the comb enables transmitted optical signal-to-noise ratios above 33 dB, while maintaining a laser pump power level compatible with state-of-the-art hybrid silicon lasers.Dark-pulse combs may be useful for coherent communications since they display high power conversion efficiency. Here, the authors report the first demonstration of coherent wavelength division multiplexing using dark pulse microresonator combs high signal-to-noise while maintaining a low on-chip pump power.

Long-haul coherent transmission using a silicon nitride microresonator-based frequency comb as WDM source

We demonstrated transmission of polarization-multiplexed quadrature phase-shift keying data over 6000 km using a low-noise silicon nitride microresonator frequency comb as light source. These results show the technologys suitability for long-haul fiber communications.

Joint Carrier Recovery for DSP Complexity Reduction in Frequency Comb-Based Superchannel Transceivers

We experimentally demonstrate a master-slave carrier recovery scheme by joint processing of 10 GBd PM-64QAM phase-locked wavelength carriers. We measure negligible penalty up to a frequency spacing of 275 GHz, showing the potential for effective resource utilization among many wavelength channels.

Phase Correlation Between Lines of Electro-Optical Frequency Combs

Simultaneous measurement of the phase noise from 49 electro-optical frequency comb lines show a correlation of over 99.99% between lines. Additionally, the phase noise difference between line pairs is correlated, verifying theoretical predictions.

ASIC Implementation of Time-Domain Digital Back Propagation for Coherent Receivers

Digital back propagation (DBP) is often proposed and implemented offline for the mitigation of nonlinear impairments in long-haul fiber communications. However, complexity in terms of chip area and power consumption in a realistic application-specific integrated circuit implementation is yet to be determined. Here, we implement time-domain DBP (TD-DBP) in a 28-nm fully-depleted silicon-on-insulator process technology, considering digital implementation aspects such as limited-resolution arithmetic and finite-length filters. We choose as example a coherent optical transmission system, viz. a single-channel, single-polarization, and 20-GBd 16-QAM system, for which the DBP is known to perform well. For the considered system, we find that the TD-DBP can enable a reach increase from 3400 to 5300 km, at a power dissipation of <20 W (or, conversely, an energy dissipation of <230 pJ/bit), at a pre-FEC BER of

Time-domain digital back propagation: Algorithm and finite-precision implementation aspects

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Frequency noise of a normal dispersion microresonator-based frequency comb

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10.3 bits/s/Hz Spectral Efficiency 54×24 Gbaud PM-128QAM Comb-Based Superchannel Transmission Using Single Pilot

We propose a nonlinear mitigation algorithm designed from an ASIC perspective, and analyze implementation aspects. Given 9 signal and 11 coefficient bits, reach is increased by 105% compared to linear compensation in single-channel 16-QAM transmission.

High Spectral Efficiency PM-128QAM Comb-Based Superchannel Transmission Enabled by a Single Shared Optical Pilot Tone

Using delayed self-heterodyne coherent detection, we characterized the FM noise across the C-band of a widely spaced microresonator-based frequency comb. The resulting linewidth depends on both the pump laser and the comb line position.