M. A. Mestre

Experimental Investigation of Inter-Modal Four-Wave Mixing in Few-Mode Fibers

We experimentally demonstrate nondegenerate four-wave mixing (FWM) between waves belonging to different spatial modes of a 5-km-long few-mode fiber (FMF). Of the three inter-modal FWM (IM-FWM) processes possible, two have been experimentally observed. These IM-FWM processes are found to be phase-matched over very large frequency separations of several Terahertz between the waves. In contrast to FWM in single-mode fibers that require operating near the zero-dispersion wavelength to achieve phase matching, IM-FWM in a FMF can be fully phase matched in the presence of large chromatic dispersion in each spatial mode.

Space-division multiplexing and all-optical MIMO demultiplexing using a photonic integrated circuit

We demonstrate a silicon photonic integrated circuit for all-optical demultiplexing of and selective coupling to the six spatial and polarization modes of a few-mode fiber (FMF). We successfully demultiplex all six modes after transmission through 30 km of FMF.

Experimental Observation of Inter-Modal Cross-Phase Modulation in Few-Mode Fibers

We experimentally demonstrate a broadband nonlinear interaction between a data-modulated pump and an unmodulated probe occupying different spatial modes of a few-mode fiber. This nonlinear interaction is attributed to inter-modal cross-phase modulation (IM-XPM) and found to be maximum when signal and probe have similar group velocities. This can correspond to a few THz of wavelength separation between waves. The magnitude of the measured IM-XPM is found to be comparable to the measured intra-modal XPM with similar nonlinear coefficients. A comparison to a semi-analytical model of XPM shows good agreement with the measurements.

Mode-Multiplexed Transmission Over a 209-km DGD-Compensated Hybrid Few-Mode Fiber Span

We transmitted five wavelength channels and six spatial and polarization modes over a 209-km-long hybrid few-mode fiber span. The fiber supports six spatial and polarization modes, and consists of a first section of large effective area depressed-cladding few-mode fiber followed by a graded-index few-mode fiber. The differential group delay is compensated by using fiber spools with differential group delay of opposite sign. Low-loss three-spot mode couplers are used to couple to the few-mode fiber, and backward pumped-distributed Raman amplification is used to overcome the fiber loss. The 40-Gb/s QPSK signals with an aggregate capacity of 1.2 Tb/s are recovered by coherent multiple-input-multiple-output off-line digital signal processing. The impulse response at various span lengths is compared and analyzed in detail.

Single Carrier 168-Gb/s Line-Rate PAM Direct Detection Transmission Using High-Speed Selector Power DAC for Optical Interconnects

We demonstrate the generation and detection of single-polarization 56-GBd PAM-8 and PAM-4 signals using intensity modulation and direct detection leveraging a novel high-speed high-output swing selector power DAC fabricated in an InP DHBT which does not require an external driver. Considering 7% overhead hard-decision forward error control, we validate our design by transmitting the 150 Gb/s net data rate signal based on PAM-8 over 2 km and 100 Gb/s signal based on PAM-4 over 4 km of standard single mode fiber without optical amplification. We complement the results by taking advantage of the high bandwidth of the selector power DAC to increase the PAM-4 symbol rate to 64 GBd and we compare it with the results at 56 GBd at constant information rate. We use the concept of mutual information to assess which Baud rate can achieve best sensitivity as a function of transmission distance.

Monolithic integrated silicon-based slot-blocker for packet-switched networks

We demonstrate a 16-channel, silicon-on-insulator, monolithic integrated slot-blocker. This silicon photonic circuit includes two arrayed waveguide gratings, 16 variable optical attenuators and two vertical fiber couplers. We successfully operate it with 56 Gb/s and 80 Gb/s QPSK optical packets.

Optical slot switching-based datacenters with elastic burst-mode coherent transponders

In a novel concept for intra-datacenter networks, we combine optical slot switching and elastic, burst-mode transponders, with variable bit-rate from 100 to 250 Gb/s depending on node count. Our scenario requires ~x400 fewer transponders than todays 10 Gb/s electronic networks.

Combined SDM and WDM transmission over 700-km Few-Mode Fiber

We experimentally demonstrate multiple-input multiple-output transmission over a 700-km few-mode fiber of a combined 3-space-, 2-polarization-, and 34-wavelength-division multiplex, using low-loss 3-spot mode couplers.

Transmission of single-carrier Nyquist-shaped 1-Tb/s line-rate signal over 3,000 km

We synthesize a single-carrier optical signal at a record 1-Tb/s line-rate, out of multiple spectral slices by joint optical and digital signal processing. The 127.9-GBd signal is successfully transmitted and detected after 3,000km distance.

Compact InP-Based DFB-EAM Enabling PAM-4 112 Gb/s Transmission Over 2 km

We demonstrate a 56-GBd pulse-amplitude modulation-4 compact InP transmitter module integrating a distributed feedback laser and an electro-absorption modulator, which exhibits 50-GHz bandwidth, >13-dB extinction ratio and up to 1.5-mW output power. Successful amplifier-free 112-Gb/s transmission is performed over 2 km using low complexity three-taps equalization. We also study the tradeoff between receiver bandwidth, equalizer length and performance, and show successful signal recovery with bandwidths as low as 18 GHz when increasing the equalizer length.