Peter J. Pupalaikis

Mode-multiplexed 6×20-GBd QPSK transmission over 1200-km DGD-compensated few-mode fiber

Low differential group delay (DGD) between the modes of a graded-index few-mode fiber is obtained by combining segments with DGD of opposite sign. Transmission of mode-multiplexed 6×20-GBd QPSK over a record distance of 1200 km is demonstrated.

Low-loss mode coupler for mode-multiplexed transmission in few-mode fiber

We present a novel low-loss 3-spot mode coupler to selectively address 6 spatial and polarization modes of a few-mode fiber. The coupler is used in a 6×6 MIMO-transmission experiment over a 154-km hybrid span consisting of 129-km depressed-cladding and 25-km graded-index few-mode fiber.

12 x 12 MIMO Transmission over 130-km Few-Mode Fiber

We demonstrate 12 x 12 multiple-input multiple-output mode multiplexed transmission over130-km of few-mode fiber of a combined 6-space-, 2-polarization-, and 8-wavelength-division multiplex, using low-loss photonic lantern and 3D-waveguide mode multiplexers.

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We demonstrate ten-channel wavelength-division-multiplexed (WDM) transmission of 56-Gbaud polarization-division-multiplexed quadrature phase-shift keying signals (i.e., at a line rate of 224 Gb/s) over 1890 km of fiber on a 100-GHz WDM grid (spectral efficiency of ~2 b/s/Hz). The coherent intradyne receiver digitizes the signal at 80 GSamples/s, and is followed by offline digital signal processing.

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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.

224-Gb/s WDM Transmission of 56-Gbaud PDM-QPSK Signals Over 1890 km of Fiber

A single-polarization 160-Gb/s (80-Gbaud) electronically time-division-multiplexed (ETDM) quadrature phase-shift-keyed (QPSK) signal is generated and coherently detected using two 45-GHz-bandwidth oscilloscope prototypes and offline processing.

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

Technologies and design considerations are presented for the design of very high bandwidth oscilloscopes. These include chip, DSP and microwave technologies employed in some of the fastest waveform digitizers in the world.

All-ETDM 80-Gbaud (160-Gb/s) QPSK Generation and Coherent Detection

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.

Technologies for very high bandwidth real-time oscilloscopes

We demonstrate a coherent receiver using a 100-GHz electrical bandwidth and 240-GS/s real-time oscilloscope as analog-to-digital converter in a 160-Gbaud QPSK system.

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

We demonstrate an all-electronic digital-to-analog converter (DAC) with 100-GHz electrical bandwidth, sampling at 240 GSa/s, based on digital band interleaving (DBI). We discuss digital predistortion techniques for compensating the nonideal performance of the high-speed and radio-frequency components in our DBI architecture. We then test the DAC by generating up to 190-GBaud Nyquist-shaped pulse amplitude modulation. We analyze the performance of the digital band interleaved DAC and demonstrate coherent detection of single-polarization optical binary phase-shift keying at 140 GBaud.