G. M. Carter

All-optical 80-gb/s time-division demultiplexing using polarization-insensitive cross-phase modulation in photonic crystal fiber

We describe an all-optical 80-Gb/s time-division demultiplexer, which utilizes cross-phase modulation in a commercial photonic crystal fiber. Compared to back-to-back 10-Gb/s measurements, the demultiplexer achieves better than a 2.5-dB power penalty for all eight channels. More importantly, we demonstrate a novel scheme for polarization-insensitive operation, which uses only the birefringence of the fiber itself and proper alignment of the clock pulse polarization. Using this technique, the polarization sensitivity of the converted power is found to be less than 0.4 dB, allowing for error-free demultiplexing even while the data polarization state is scrambled

Polarization-insensitive optical clock recovery at 80 Gb/s using a silicon photodiode

We report an optical clock recovery system that uses two-photon absorption in a conventional silicon photodiode to synchronize a 10-GHz optical clock to an 80-Gb/s data stream. Compared to many other clock recovery techniques, the system is economical, polarization-insensitive, and can operate over a broad range of optical wavelengths. The system was tested back-to-back and in a 110-km transmission experiment, achieved error-free performance in all cases, and exhibits a root-mean-square timing jitter of 120 fs. Low timing jitter is maintained even in the presence of slow or fast polarization fluctuations.

Erratum to “Polarization-Insensitive Wavelength Conversion by FWM in a Highly Nonlinear PCF of Polarization-Scrambled 10-Gb/s RZ-OOK and RZ-DPSK Signals”

Wavelength conversion of polarization-scrambled 10-Gb/s on-off keyed and differential phase-shift-keyed signals for which the pulse format was 33% return-to-zero, has been achieved by partially degenerate four-wave mixing in a record 20-m-short highly nonlinear photonic crystal fiber. It was found that a minimum pump-probe detuning of ~9 nm was required to achieve polarization-insensitive wavelength conversion of <1 dB, resulting in a 10-9-receiver sensitivity penalty of <1 dB, for both modulation formats.

All-Optical Wavelength Conversion of 10 Gb/s RZ-OOK Data in a Silicon Nanowire via Cross-Phase Modulation: Experiment and Theoretical Investigation

Wavelength conversion of a 10 Gb/s 2.7%-duty-cycle return-to-zero (RZ) OOK (RZ-OOK) signal using XPM in a compact silicon nanowire waveguide (Si nanowire) and a detuned filter is successfully demonstrated for the first time. A 10-9-BER receiver sensitivity penalty of <;1 dB was measured for the converted signal relative to the baseline signal, with a filter-probe detuning of 0.6 nm. The system is numerically modeled and the results are shown to match well with the experimental results. The numerical model is further used to design an optimal filter that would eliminate filter-probe detuning.

Wavelength Conversion of 10-Gb/s RZ-OOK Using Filtered XPM in a Passive GaAs–AlGaAs Waveguide

Wavelength conversion of a 10-Gb/s return-to-zero on-off-keyed (RZ-OOK) signal has been achieved using transient cross-phase modulation in a passive GaAs-AlGaAs bulk-waveguide, followed by a detuned filter. The converted RZ-OOK signal showed a power penalty of <1 dB at a bit-error-rate of 10-9 relative to the baseline RZ-OOK signal.

160-Gb/s Polarization-Independent Optical Demultiplexing in 2-m Nonlinear Fiber

We report a new method for polarization-independent optical demultiplexing that uses cross-phase modulation (XPM) in nonlinear fiber. Using this technique, we achieved error-free 160- to 10-Gb/s demultiplexing in only 2 m of highly nonlinear bismuth-oxide fiber. The demultiplexing performance is not impaired when the input data polarization state is scrambled at high speed. This method does not require circular polarization states and is shown to work even in birefringent fibers. We present a simple theoretical model that predicts the conditions under which polarization-independent XPM can be achieved, and we show numerical simulations that agree well with experimental observations

XPM-induced impairments in RZ-DPSK transmission in a multi-modulation format WDM system

We investigate the impact of XPM-induced penalties on a RZ-DPSK channel due to NRZ-ASK neighbors in a WDM transmission system, and examine the dependence on channel spacing and launch polarization.

Performance of DBPSK in a 5 /spl times/ 10 Gb/s mixed modulation format Raman/EDFA WDM system

The impact of varying the pulse format as well as the data format of side channels on a differential binary phase-shift-keyed (DBPSK) center channel, as a function of channel spacing and propagation distance, was examined for the first time in a 5 /spl times/ 10 Gb/s Raman/erbium-doped fiber amplifier wavelength-division-multiplexed recirculating loop. The data format of the side channel was either on-off keying (OOK) or DBPSK, while its pulse format was either 50% return-to-zero or nonreturn-to-zero. For the system studied, it was found that the side channel OOK data format was always more detrimental than its pulse format to the performance of the DBPSK center channel.

Polarization-Insensitive Wavelength Conversion by FWM of 100-GHz-Spaced DWDM 4

Polarization-insensitive (PI) wavelength conversion of 100-GHz-spaced wavelength-division multiplexed 4 × 10 Gb/s return-to-zero binary phase-shift keyed (RZ-BPSK) signals was successfully demonstrated utilizing four-wave mixing for the first time in a passive, birefringent nonlinear AlGaAs waveguide. In addition to a pump launch angle adjustment, a minimum pump-probe detuning was also required to mitigate polarization-induced power fluctuations in the probe. The PI-wavelength-converted signals all demonstrated a pre-amplified receiver sensitivity penalty of less than ≈ 2 dB at 10-9 bit-error-rate, relative to their respective baseline RZ-BPSK signals.

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By utilizing cross-phase modulation and birefringence, we demonstrated simultaneous polarization-insensitive phase-transmultiplexing and multicasting of a single 10-Gbaud CSRZ-OOK signal and 4 × 10-Gbaud RZ-BPSK signals to generate 4 × 10-Gbaud RZ-QPSK signals in a photonic crystal fiber. The measured receiver sensitivity OSNR penalty at BER of 10-9 was ≈1.8 dB, relative to the FPGA-precoded RZ-DQPSK baseline, for a randomly polarized CSRZ-OOK signal, when the launch angles of all RZ-BPSK signals were fixed at ≈ 45°. In addition, the OSNR of the remotely generated CSRZ-OOK signal could be degraded down to ≈34 dB/0.1 nm, before the BER performance of the phase-transmultiplexing and multicasting operation began to degrade.