Xinli Jiang

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.

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.

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.

6.3-Tb/s unrepeatered transmission over 402-km fiber using high power Yb-free clad-pumped L-band EDFA

Unrepeatered transmission of 6.3-Tb/s (63×128-Gb/s) signals over 402-km of effective-area (Aeff) managed fiber link is achieved by employing high power Yb-free clad-pumped L-band EDFA and remote optically pumped amplifier, which is counter-propagating 2nd-order Raman pumped.

Demonstration of broadband inter-modal four-wave mixing in graded-index few-mode fibers

We experimentally demonstrate broadband four-wave mixing (FWM) between two spatial modes of a 5-km-long few-mode fiber. We show that, in contrast to FWM in single-mode fibers, inter-modal FWM (IM-FWM) can be better phase matched for waves well separated in frequency (a few THz) than when they are closely spaced (tens of GHz).

800Gb/s (8x128Gb/s) unrepeatered transmission over 515-km large-area ultra-low-loss fiber using 2nd-order Raman pumping

We demonstrate unrepeatered transmission of 8x128Gb/s PDM-QPSK signals over a 515k-m fiber link. This ultra-long distance of 800 Gb/s unrepeatered transmission in a single fiber configuration is achieved by employing enabling techniques such as large-effective-area ultra-low-attenuation fibers, co-propagating and counter-propagating 2nd-order-pumped distributed Raman amplification, and remote optically pumped amplifier (ROPA). The ROPA itself is also counter-propagating 2nd-order Raman pumped. The designs and characteristics of the ROPA and 2nd-order pumped distributed Raman amplification are described, and optimization of the transmission performance of this ultra-long reach 800Gb/s unrepeatered transmission fiber link is discussed in this paper.