Thomas Torounidis

Fiber-optical parametric amplifier with 70-dB gain

A record optical fiber gain of 70 dB was obtained in a continuous-wave pumped fiber-optical parametric amplifier. Limitations due to saturation effects from amplified spontaneous emission (ASE) and due to stimulated Brillouin scattering in this unidirectional amplifier are discussed. The spectral density of ASE was up to 180 mW/nm in agreement with theoretical expectations, illustrating the possible use as a high brightness optical noise source

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.

Broadband Single-Pumped Fiber-Optic Parametric Amplifiers

We analyze the impact of pump phase modulation (PM) on the bandwidth of single-pumped fiber-optic parametric amplifiers. The measured values and the calculations show that the impact on bandwidth by pump PM is small compared to the impact from the dispersion curvature. A bandwidth of 100 nm with a gain of 11.5plusmn2 dB is achieved. This is also used to build a widely tunable fiber ring laser

Fiber optical parametric amplifier pulse source: theory and experiments

An evaluation of a fiber optical parametric amplifier (FOPA)-based pulse source in terms of pulse width and chirp is presented. Experiments are performed when operating the FOPA as a pulse source, requiring a sinusoidally modulated pump. The FOPA is generating pulses at 10 GHz, and are measured using a streak camera capable of measuring pulses as a function of time, wavelength, and intensity. Experimental results are presented together with a theory for chirp and pulse widths that show good agreement.

Signal generation and transmission at 40, 80, and 160 Gb/s using a fiber-optical parametric pulse source

Short return-to-zero pulses (/spl sim/2 ps) are generated at bit rates of 40, 80, and 160 Gb/s using a fiber-optical parametric amplifier. The performance of the parametric pulse source is evaluated both back-to-back and in a 110-km transmission link. A receiver sensitivity of -33 dBm back-to-back was achieved after demultiplexing from 160 to 10 Gb/s. The power penalty at 160 Gb/s due to 110-km transmission was less than 2 dB. Very short pulses (0.5 ps) were also achieved when using the parametric amplifier as a compressor.

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.

Noise Statistics in Fiber Optical Parametric Amplifiers

We show both theoretically and experimentally that the probability density function of a signal amplified by parametric amplifiers with pump excess noise is non-Gaussian and asymmetric. This impacts the relationship between the noise figure and the bit-error rate.

Fiber-optic parametric amplifier in a loop mirror configuration

A configuration of the fiber-optic parametric amplifier (FOPA) using an optical loop mirror is presented and evaluated. Previously presented setups usually suffer a 10-dB loss on the input for the signal wavelength. The setup presented in this letter allows, in principle, virtually lossless combination and separation of pump and signal. In addition, over 30-dB suppression of the pump was achieved in this configuration. Bit-error-rate measurements using the FOPA as preamplifier were compared to a thermal limited receiver. The receiver sensitivity for the FOPA was -30 dBm, which was 10 dB better than the thermally limited receiver.

Fiber optical parametric amplifier in WDM applications

We demonstrate for the first time experimentally the performance of fiber-based optical parametric amplifiers in WDM applications. Limitations due to pump depletion and four-wave mixing are quantified.

Noise statistics of fiber optical parametric amplifiers

In this paper, we show both theoretically and experimentally that the probability density function of the intensity of an amplified signal by parametric amplifiers subject to a pump with excess noise is highly asymmetric. This is due to the nonlinear relationship between the optical pump power and the parametric gain. Because of this, the relationship between the noise figure (NF) and the bit error rate (BER) is modified, compared with that predicted by the chi2 theory, which is an effect that is notable at large NFs and low BERs. The difference in predicted BER can be of several orders of magnitudes between the correct theory and the chi2 approximation in single-stage parametric amplifiers. We also show that in the limit of many cascaded parametric amplifiers, the statistics of the noise of an amplified optical signal approaches chi2. Furthermore, the BER of a parametric amplifier is generally lower compared with erbium-doped fiber amplifiers for the same NF values if we assume quantum-limited amplification