Transmission of optical communication signals by distributed parametric amplification

We have demonstrated, for the first time to our knowledge, distributed parametric amplification, i.e. amplification of 10-Gb/s communication signals along a 75-km transmission fiber by using a co-propagating pump with only 66.5 mW of power.published_or_final_versio

Improvement of optical signal-to-noise ratio of a high-power pump by stimulated Brillouin scattering in an optical fiber

We propose and demonstrate improvement of optical signal-to-noise ratio of a highpower pump by saturated stimulated Brillouin amplification of a backward seed in a fiber. A 27-dB improvement was obtained for a 1-W pump

Stokes-space formalism for Bragg scattering in a fiber

Optical frequency conversion by four-wave mixing (Bragg scattering) in a fiber is considered. The evolution of this process can be modeled using the signal and idler amplitudes, which are complex, or Stokes-like parameters, which are real. The Stokes-space formalism allows one to visualize power and phase information simultaneously, and produces a simple evolution equation for the Stokes parameters

Recent advances in the design and implementation of practical fiber optical parametric amplifiers

Conference on Optoelectronic and Microelectronic Materials and Devices, Brisbane, Australia, 8-10 December 2004Fiber optical parametric amplifiers (OPAs) are based on the third-order nonlinear susceptibility of glass fibers. If two strong pumps and a weak signal are fed into a fiber, an idler is generated. Signal and idler can grow together if pump power is high enough, and phase matching occurs. In recent years, impressive performance has been demonstrated in several respects: 1) Gain in excess of 60 dB has been obtained; 2) fiber OPAs can exhibit a large variety of gain spectra: a gain bandwidth of 400 nm has been demonstrated; tunable narrowband gain regions can also be generated; 3) Noise figure of 3.7 dB, limited by other third-order nonlinear process; 4) Polarization-insensitive operation in both one-pump and two-pump configurations; 5) The presence of the idler can be used for wavelength conversion. Also, the spectrum of the idler is inverted with respect to that of the signal; thus by placing an OPA in the middle of a fiber span one can realize mid-span spectral inversion (MSSI) which counteracts the effect of fiber dispersion and some nonlinear effects. Besides using fiber OPA in continuous-wave regime as in typical systems, pulsed-pump has also been demonstrated to achieve larger bandwidth and higher peak gain by combining with optical filtering technique. Furthermore, by modulating the pump it is possible to modulate signal and/or idler at the output. This can be used to implement a variety of signal processing functions, including: fast signal switching; demultiplexing of time-division-multiplexed signals; retiming and reshaping of waveforms; optical sampling. A number of challenges must be overcome in order for fiber OPAs to be useful in communication applications. In multi-wavelength systems, these are: four-wave mixing, cross-phase modulation; and cross-gain modulation between signals. Furthermore, the pump-to-signal relative intensity noise (RIN) transfer and frequency/phase modulation (FM/PM) to signal intensity conversion are also potential challenges for practical fiber OPAs. © 2005 IEEE.published_or_final_versio

Pump-to-signal transfer of low-frequency intensity modulation in fiber optical parametric amplifiers

This paper describes the theoretical and experimental investigation of the transfer of low-frequency intensity modulation (IM) from pump to signal in fiber optical parametric amplifiers (OPAs). It is first established that low-frequency IM of the pump remains unchanged over the length of the amplifier in spite of the presence of parametric gain. The pump-power dependence of the OPA gain is then used to calculate the instantaneous effect of pump IM on the signal and idler output powers. These calculations are performed for both one- and two-pump OPAs. The main predictions are that 1) the ratio ρ of the signal intensity modulation depth to that of the pump varies across the OPA gain spectrum and 2) for a 20-dB gain, ρ can exceed 10 at some wavelengths, which indicates that this effect can be detrimental. Experiments have been performed to verify these predictions. Using sinusoidal IM of the pump, the resulting amplified signal IM was measured, and the experimental results were found to be in good agreement with the theoretical predictions. © 2005 IEEE.published_or_final_versio

Ultrafast and versatile spectroscopy by temporal Fourier transform

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Theory of quantum frequency translation of light in optical fiber: application to interference of two photons of different color

We study quantum frequency translation and two-color photon interference enabled by the Bragg scattering four-wave mixing process in optical fiber. Using realistic model parameters, we computationally and analytically determine the Green function and Schmidt modes for cases with various pump-pulse lengths. These cases can be categorized as either "non-discriminatory" or "discriminatory" in regards to their propensity to exhibit high-efficiency translation or high-visibility two-photon interference for many different shapes of input wave packets or for only a few input wave packets, respectively. Also, for a particular case, the Schmidt mode set was found to be nearly equal to a Hermite-Gaussian function set. The methods and results also apply with little modification to frequency conversion by sum-frequency conversion in optical crystals

Recent Developments In European Union Crisis Management Operations

The European Union (EU) has the possibility to plan, establish, and launch crisis management operations on the basis of Articles 42(4) and 43(2) of the Treaty on European Union (TEU).\u2