Fiber Optical Parametric Amplifier Research Articles

Phase noise in fiber-optic parametric amplifiers and converters and its impact on sensing and communication systems

We present a theoretical analysis describing the spectral dependence of phase noise in one-pump fiber parametric amplifiers and converters. The analytical theory is experimentally validated and found to have high predictive accuracy. The implications related to phase-coded sensing and communications systems are discussed.

Influence of the zero dispersion wavelength fluctuation on the gain and noise performance in dual-pump fiber parametric amplifiers

Because of the zero dispersion wavelength (ZDWL) random fluctuations, the gain and noise figures deteriorate in optical parametric amplifiers based on highly nonlinear fibers (HNLFs). The detrimental role of ZDWL fluctuations on the gain and noise performance in dual-pump fiber optical parametric amplifiers (FOPAs) is presented. Numerical investigations of noise figure (NF) for different fibers with random fluctuation are analyzed. The noise figures for different fibers are varying even if the random fluctuation is small. Through choosing HNLFs with low ZDWL fluctuation and large nonlinear coefficient, high-gain and low-noise performance can be obtained.

Bandwidth-efficient phase modulation techniques for Stimulated Brillouin Scattering suppression in fiber optic parametric amplifiers

Two novel bandwidth efficient pump-dithering Stimulated Brillouin Scattering (SBS) suppression techniques are introduced. The techniques employ a frequency-hopped chirp and an RF noise source to impart phase modulation on the pumps of a two pump Fiber Optical Parametric Amplifier (FOPA). The effectiveness of the introduced techniques is confirmed by measurements of the SBS threshold increase and the associated improvements relative to the current state of the art. Additionally, the effect on the idler signal integrity is presented as measured following amplification from a two pump FOPA employing both techniques. The measured 0.8 dB penalty with pumps dithered by an RF noise source, after accruing 160 ps/nm of dispersion with 38 dB conversion gain in a two-pump FOPA is the lowest reported to date.

Theoretical demonstration for signal gain in multiple four-wave mixing processes based on cubic susceptibility medium

An insight into the signal gain in multiple four-wave mixing (MFWM) processes based on a cubic susceptibility medium is theoretically proposed and demonstrated. A dual-pumped fiber optical parametric amplification (FOPA) model is developed with the exact expressions for the signal gain and its 3-dB bandwidth successfully yielded.With these analytical expressions, we show that when pump-1 and pump-2 wavelengths tuned at 1549 and 1551.02 nm, the 3-dB bandwidth of the signal gain can be achieved at about 2253.4 nm theoretically by properly setting the pumped powers. Numerical simulations show that there is a small pinnacle emerging in the signal gain spectrum owing to the degenerate OPA process occurring. The proposed OPA model can find potential applications in all-optical wavelength conversion, optical amplifier, and all-optical sampling.

1-Tb/s DWDM Long-Haul Transmission Employing a Fiber Optical Parametric Amplifier

In this letter, we report the performance of a fiber optical parametric amplifier (OPA) when used as a source or intermediate node amplifier in a dense wavelength-division-multiplexed (DWDM) long-haul transmission testbed with 26 DWDM channels modulated at 43.7-Gb/s return-to-zero differential phase-shift keying. In both scenarios, we demonstrate similar performance to an erbium-doped fiber amplifier. This shows the OPAs compatibility with high-capacity (>1 Tb/s) long-haul communication systems.

Modeling and measurement of the noise figure of a cascaded non-degenerate phase-sensitive parametric amplifier

Semi-classical noise characteristics are derived for the cascade of a non-degenerate phase-insensitive (PI) and a phase-sensitive (PS) fiber optical parametric amplifier (FOPA). The analysis is proved to be consistent with the quantum theory under the large-photon number assumption. Based on this, we show that the noise figure (NF) of the PS-FOPA at the second stage can be obtained via relative-intensity-noise (RIN) subtraction method after averaging the signal and idler NFs. Negative signal and idler NFs are measured, and <2 dB NF at >16 dB PS gain is estimated when considering the combined signal and idler input, which is believed to be the lowest measured NF of a non-degenerate PS amplifier to this date. The limitation of the RIN subtraction method attributed to pump transferred noise and Raman phonon induced noise is also discussed.

Character analysis of slow light with communication waveband in fiber optical parametric amplifier

The comprehensive characters of delay time and delay bandwidth with distortion, signal wavelength dependence and delay bandwidth product in fiber optical parametric amplifier are investigated theoretically when the pump locates at anomalous dispersion region. The delay character of single pulse, data stream with certain bit pattern and pseudo random data stream are analyzed comprehensively. In this category of fiber optical parametric amplifier, the delay time and delay bandwidth product vary from signal wavelengths and bit rates. For the same nonlinear coefficient, pump power and fiber length, the diverse dependences of bit pattern in different signal wavelengths are found by numerical simulation. The impacts of pump power and fiber length on the delay character and distortion are also discussed. These relations are conductive to the design of slow light based on fiber optical parametric amplifier in telecommunication waveband.

Simultaneous Dual-Channel Retiming and Reshaping Using Two Independent Phase Clocks in Fiber-Optic Parametric Amplification

We propose a novel scheme for simultaneous retiming and reshaping of two wavelength-division-multiplexing channels using two independent phase clock pump and polarization multiplexing in fiber-optic parametric amplification, with the benefits of suppressing the interchannel cross-phase-modulation effect induced by the clock pumps and four-wave-mixing crosstalk. Operation of two 10-Gb/s channels is demonstrated experimentally. In both single- and dual-channel operation, eye diagrams after regeneration are significantly cleared with pulsewidth narrowed, and the nonlinear interferences are effectively reduced. An average 2-dB power penalty improvement at a bit-error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> is obtained in both single- and dual-channel operation.

Experimental demonstration of optical parametric chirped pulse amplification in optical fiber

We experimentally demonstrate optical parametric chirped pulse amplification for the first time (to our knowledge) in a completely integrated all-fiber optical system. A single chirped fiber Bragg grating, achieving both the stretching and compression stages, is combined with a cw-pumped fiber optical parametric amplifier. As a proof of principle, we demonstrate the amplification of picosecond Fourier-transform-limited pulses at 1550nm.

Investigation on noise characteristics of dual-pumped fiber optical parametric amplifiers based on photonic crystal fibers

The noise characteristics of dual-pumped fiber optical parametric amplifiers (FOPAs) induced by gain and loss in photonic crystal fibers (PCFs) are analyzed. A special photonic crystal fiber is designed. Its noise figure (NF) changes with structure parameters, and it decreases as the hole diameter decreases. Three factors including input-signal power, signal wavelength and pump separation which impact on the final noise figure are discussed with the designed PCF.

Gain statistics of a fiber optical parametric amplifier with a temporally incoherent pump

We present an investigation of the statistics of the gain fluctuations of a fiber optical parametric amplifier pumped with a temporally incoherent pump. We derive a simple expression for the probability distribution of the gain of the amplified optical signal. The gain statistics are shown to be a strong function of the signal detuning and allow the possibility of generating optical gain distributions with controllable long-tails. Very good agreement is found between this theory and the experimentally measured gain distributions of an incoherently pumped amplifier.

Thermal noise for SBS suppression in fiber optical parametric amplifiers

We demonstrate a new and simple solution to suppress stimulated Brillouin scattering in fiber optical parametric amplifiers. Cumbersome PRBS or sinusoidal generators used to broaden the pump spectrum are replaced by a filtered microwave noise source. Stimulated Brillouin scattering threshold can be increased up to large values still keeping an excellent quality of amplification of nonreturn to zero signals. The simplicity and the performances of this setup open the way for a wide variety of applications for FOPAs.

Raman-Induced Asymmetric Pump Noise Transfer in Fiber-Optical Parametric Amplifiers

In this letter, a theoretical model accounting for the asymmetric transfer of pump noise in the gain spectrum of a single-pump fiber parametric amplifier due to the Raman effect is presented. The model is satisfactorily verified by the experiments. The experiments demonstrate that the pump electrical signal-to-noise ratio remains unchanged in contrast to the optical signal-to-noise ratio which decreases along the fiber.

Detailed characterization of a fiber-optic parametric amplifier in phase-sensitive and phase-insensitive operation

We experimentally demonstrate a single-pumped, non-degenerate phase-sensitive parametric amplifier with a precise control of phase and amplitude of the in-going waves and investigate in detail its gain, attenuation and saturation properties in comparison with operation in phase insensitive amplifier (PIA) mode. We experimentally observe the variation of the gain and attenuation as a function of the relative phase, pump power and the signal-idler power ratio. The phase sensitive gain spectrum is studied over a 24 nm symmetrical bandwidth and we achieve a maximum phase sensitive amplification (PSA) gain of 33 dB. A departure from the theoretical maximum attenuation as the gain increases is observed and explained.

Tunable single-longitudinal-mode fiber optical parametric oscillator

A tunable single-longitudinal-mode (SLM) fiber optical parametric oscillator (FOPO) is proposed and demonstrated experimentally. A sub-ring cavity with a short cavity length is used to suppress the longitudinal modes and broaden the longitudinal mode spacing. A fiber loop mirror, consisted of an unpumped erbium-doped fiber, acts as an autotracking filter for providing fine mode restriction and ensuring the single-frequency operation. The measurement based on a homodyne method shows that the FOPO provides the SLM output. Furthermore the SLM FOPO can be tunable over 14 nm for each of the signal and the idler, which is limited only by the gain bandwidth of the fiber optical parametric amplifier.

Full characterization of the signal and idler noise figure spectra in single-pumped fiber optical parametric amplifiers

For the first time, four different noise sources, which are amplified quantum noise, Raman phonon seeded excess noise, pump transferred noise (PTN), and pump residual noise, are considered simultaneously to model the wavelength-dependent noise figure in a single-pumped fiber optical parametric amplifier. An asymmetric signal NF spectrum induced by both Raman phonon seeded excess noise and Raman gain modified PTN is measured in the electrical domain. Theoretical results agree very well with the experimental data. The idler NF spectrum is also analyzed and measured, which shows a more symmetric profile.

Wavelength-swept spectral and pulse shaping utilizing hybrid Fourier domain modelocking by fiber optical parametric and erbium-doped fiber amplifiers

We report the first Fourier domain modelocked (FDML) laser constructed using optical parametric amplifier (OPA) in conjunction with an erbium-doped fiber amplifier (EDFA), centered at approximately 1555 nm, to the best of our knowledge. We utilize a one-pump OPA and a C-band EDFA in serial configuration with a tunable Fabry-Perot interferometer to generate a hybrid FDML spectrum. Results demonstrate a substantially better spectral shape, output power and stability than individual configurations, with decreased sensitivity to polarization changes. We believe this technique has the potential to enable several amplifiers to complement individual deficiencies resulting in improved spectral shapes and power generation for imaging applications such as optical coherence tomography (OCT).

Gain spectrum of an optical parametric amplifier with a temporally incoherent pump

We experimentally investigate the performance of a fiber optic parametric amplifier pumped with a temporally incoherent pump. The measured gain curves are compared with both a simple theory capable of predicting the maximum attainable mean incoherent parametric gain and full numerical simulations of the nonlinear Schrödinger equation. Parametric gain slopes seven times higher than that of an equivalent coherently pumped parametric amplifier are reported.

Investigation on all-optical regeneration of asynchronous dual-wavelength signals based on fiber-optic parametric amplification

With the continued development of the wavelength division multiplexing (WDM) network, there arises an urgent demand for the research of multi-wavelength all-optical 3R regeneration. In this paper, a novel multi-wavelength all-optical regeneration scheme has been proposed. Using phase clock in the fiber-optic parametric amplification and polarization multiplexing, all-optical regeneration of dual-wavelength signals generated by two independent WDM transmitter is realized. Theoretical analysis is carried out for the operation mechanism of the amplitude noise suppression using the gain saturation of the parametric amplification, and re-timing using phase modulation with cascading dispersion. Dual-wavelength 10 Gbit/s signal optical regeneration is demonstrated experimentally. Experimental results show that the inter-channel nonlinearities like four-wave mixing and cross phase modulation are effectively reduced. In the single and dual-wavelength cases, signal to noise ratio improvements of at least 6.5 dB and 4.5 dB have been achieved, respectively, after regeneration. Bit error rate test shows that about 2 dB power penalty improvement is obtained in both single- and dual-wavelength operations.

Burst-mode amplification of dynamic optical packets using fibre optical parametric amplifier in optical packet networks

The burst-mode amplification performance of a fibre optical parametric amplifier (FOPA) is experimentally investigated. Compared to an EDFA, no serious transient effect was observed for amplified optical packets even with a low traffic granularity, due to the fast response of the FOPA.