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The performance of a black-box Raman-assisted PSA amplifier is experimentally evaluated. In a 20-Gbaud QPSK system, more than 25dB net gain is demonstrated. Comparing to a 4dB-noise-figure EDFA, ∼1.5dB ASE noise level reduction is observed.
A cascaded configuration of Parametric Amplifiers (PA) using distributed Raman amplification is proposed to selectively extract either of QPSK channels in a WDM system. Wavelength selectivity is obtained by changing PA pump wavelength and phase.
A Raman-assisted PSA scheme is proposed with the phase matching condition achieved by PSA pump wavelength tuning. More than 10dB signal gain and 2dB sensitivity improvement are experimentally demonstrated by a typical 20G-baud QPSK system.
We investigated the effect of residual chromatic dispersion on phase-sensitive amplification of 20Gbaud 16QAM signals experimentally. We observed negligible impacts on amplification although the constellation is degraded in proportion to the amount of CD.
We first demonstrated a Raman-assisted phase sensitive amplifier, which has no optical fiber path separation between pump and signal to achieve negligible power fluctuation. Better noise performance of the proposed scheme was verified with BER measurements as comparing to EDFA.
We investigated various PSA schemes for phase regeneration and compared applicability to QPSK and higher-level formats. We demonstrated a polarization-diversity PSA to support a dual-polarization signal. Optical parametric amplifier may be one of the solutions to squeezing amplitude noise.
An optical signal level swapping function and a multi-level amplitude noise mitigation method are proposed using three parametric gain regions. Experiments demonstrate less than 1% EVM-penalty for swapping and multi-level amplitude noise mitigation is achieved.
We demonstrate 51.1-Tb/s multi-core fiber transmission using cladding pumped 7-core EDFAs and confirmed a reachable distance of 2,520 km with 73 × 100-Gbit/s Nyquist-pulse-shaped DP-QPSK signals per core.
We experimentally demonstrate tunable phase-noise mitigation and automatic frequency/phase locking to a “local” pump laser for a 20–32 Gbaud QPSK homodyne receiver using nonlinear optical signal processing. For the input noisy signal, open eye-diagrams are obtained for in-phase and quadrature components and ∼2 dB OSNR gain is achieved at BER 10−3.
We experimentally demonstrate ultra-long-haul multi-core fiber transmission using a cladding pumped 7-core erbium-doped fiber amplifier. We confirm 76 × 128-Gbit/s Nyquist-pulse-shaped DP-QPSK signals are successfully transmitted over 4,200-km 7-core fiber.
We developed a cladding pumped multicore EDFA with a compact packaged housing. Output power more than 20 dBm and NF less than 6 dB in L-band, with power consumption of 33 W were confirmed.
We propose an all-optical regeneration consisting of a phase quantizer based on delay and summation of higher harmonics and an optical amplitude squeezer. We experimentally demonstrate phase noise reduction of 40% and OSNR-gain of 3dB at BER 10−3 for 30-Gbaud QPSK signals.
We report some recent research activities of multicore EDFAs with cladding-pumped technology. We successfully developed cladding-pumped MC-EDFAs with C-band L-band application, respectively. Cladding-pumped L-band MC-EDFA realized output power of 19 dBm for each core between 1576–1603 nm with 33 % reduced power consumption.
Seven-core MC-EDFA pumped with single MM-LD optimized for L-band is developed. Output power of 19 dBm for each core is realized between 1576-1603nm with 33% reduced power consumption.
We demonstrate a single-pumped fiber optical parametric amplifier using alternately concatenated highly nonlinear fibers and pump-phase shifters for quasi-phase matching. Gain bandwidth with 1-dB flatness is 25 nm. Noise figure is less than 4 dB.
We optimize 7-multicore erbium-doped fiber amplifier for DWDM systems. Each core of MC-EDF is pumped by LD individually with bundled fan-in. The MC-EDFA has gain of 15 dB and NF of 6 dB within C-band.
We have developed a 19-SDM transmission system consisting of a new low-crosstalk 19-core fiber and a prototype 19-core EDFA. The EDFA uses shared free-space optics to couple pump light into cores and thus is SDM transparent. Recirculating loop experiment with PDM-QPSK signals shows the system feasibility for long-haul transmission over 900 km.
Amplification characteristics of MC-EDFA are reviewed. Applicability to future network is evaluated by utilizing core-pumping configuration. In addition, cladding-pumping configuration, which has possibilities for reducing power consumption and downsizing, is demonstrated.
We demonstrate 140.7-Tbit/s, 7,326-km transmission of 7×201-channel 25-GHz-spaced Super-Nyquist-WDM 100-Gbit/s optical signals using seven-core fiber and full C-band seven-core EDFAs. The record capacity-distance product of 1.03 Exabit/skm is achieved.
We report fabrication of a 45.5-km seven-core fiber with enlarged Aeff and a high-power seven-core EDFA with 5-THz bandwidth. Using them, we confirmed the feasibility of 100-Tbit/s-class transoceanic transmission.
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