P.O. Hedekvist

Amplification of WDM signals in fiber-based optical parametric amplifiers

We demonstrate for the first time, experimentally, the performance of fiber-based optical parametric amplifiers in wavelength-division-multiplexed (WDM) applications. Both a 3 /spl times/ 10 Gb/s and a commercial 7 /spl times/ 2.5 Gb/s WDM system are investigated together with the parametric amplifier. Limitations due to pump depletion and four-wave mixing are quantified. Measurements showing the performance in terms of power penalty and gain versus input-output signal power are presented.

Noise characteristics of fiber-based optical phase conjugators

This paper presents a theoretical and experimental analysis of the noise characteristics of a fiber based optical phase conjugator. The results are used to derive an expression for the noise figure (NF) of the device. The lowest measured NF is 18 dB, at -15 dB net conversion efficiency. This NF was limited by stimulated Brillouin scattering (SBS) and amplified spontaneous emission from an optical amplifier. Using the experimental parameters, the theoretical values agree well with the measurements, and predicts in our particular case a minimum NF of 10 dB at high conversion efficiencies. Furthermore, we investigate the influence of optical amplifiers before and after the conjugator, and, with all excess noise eliminated, we predict the quantum limit of 3 dB at efficiencies much greater than 100%.

Long-term 160 Gb/s-TDM, RZ transmission with automatic PMD compensation and system monitoring using an optical sampling system

Long-term measurements (10 hrs) of a 160 Gbit/s, single wavelength, RZ-system with automatic PMD compensation are demonstrated for the first time. The 186 km dispersion managed transmission system performance is also, for the first time, quantified in terms of Q-value using a real-time eye-diagram monitor based on all-optical sampling.

40-Gb/s transmission using RZ-pulse source based on fiber optical parametric amplification

We quantify the transmission properties of a high-power return-to-zero pulse source based on a fiber optical parametric amplifier. Both the amplified signal and the wavelength-translated idler are evaluated, and the differences in performance in a transmission link are shown. The pulse source emits short pulses with high extinction ratio and the quality is high enough for optical time-division multiplexing from 10 to 40 Gb/s, which is verified with bit-error-rate (BER) measurements after optical demultiplexing. We also show how the pulse source performs in a 40-Gb/s electrical time-division-multiplexed system, where the BER is measured with an electrical 40-Gb/s BER test equipment.

Impact of spectral inverter fiber length on four-wave mixing efficiency and signal distortion

We compare the performance of spectral inversion through four-wave mixing in a long (13.5 km) and a short (1.5 km) dispersion-shifted optical fiber, respectively. While the effectiveness of the long fiber is limited by nonlinear phenomena such as stimulated Brillouin scattering and cross-phase modulation, the effectiveness of the short fiber is limited only by the available power, since the critical power levels where the deleterious nonlinear phenomena occur increase when the fiber length decreases. With the requirement of negligible spectral deformation of the inverted signal, the shorter fiber gives 60% higher conversion efficiency and four times more converted optical power. Measured with 12-nm wavelength conversion from the signal to the inverted replica. >

Single-wavelength 40 Gb/s soliton field transmission experiments over 400 km fibre without in-line control

We report single-wavelength 40-Gbit/s soliton transmission over 400-km installed fiber lines in Sweden. Both polarization-division multiplexed and parallel solitons were transmitted. The system performance is dominated by the polarization-mode dispersion.