Characterization of Phase-Sensitive and Phase-Insensitive Fiber Optical Parametric Amplifiers

The topic of this thesis is fiber optical parametric ampliers (FOPA). A unique feature of such ampliers is that they can operate in both phase-insensitive and phase-sensitive mode. The latter offers the potential of amplification without any added noise. FOPAs are based on a fiber nonlinearity known as four-wave mixing (FWM) and require one or two high-power optical pump waves. In addition to amplifying the signal, a new wavelength component, called the idler wave, will be generated. Two problems for all kinds of FOPAs are the stimulated Brillouin scattering (SBS) effect that can limit the pump power, and the fact that the nonlinear fibers have a non-uniform dispersion. A method for suppressing the SBS and simultaneously controlling the dispersion is presented and evaluated. By using two pumps, flat and broadband gain can be achieved, but this is typically limited by the available pump wavelengths. The generation of a high-power pump outside the conventional wavelength range is demonstrated, and applied in a two-pump FOPA with very broadband gain. To operate in phase-sensitive mode, the FOPA requires the idler wave to be present at the input, and that all waves are phase-correlated. The use of a first stage based on FWM to achieve this is presented, and a second stage operating in phase-sensitive mode is characterized in terms of gain, and in another experiment, the unique phase-squeezing property was characterized using a coherent receiver. This property is also exploited to demonstrate all-optical phase regeneration of phase-encoded data

Characterization of Phase-Sensitive and Phase-Insensitive Fiber Optical Parametric Amplifiers

The topic of this thesis is fiber optical parametric ampliers (FOPA). A unique feature of such ampliers is that they can operate in both phase-insensitive and phase-sensitive mode. The latter offers the potential of amplification without any added noise. FOPAs are based on a fiber nonlinearity known as four-wave mixing (FWM) and require one or two high-power optical pump waves. In addition to amplifying the signal, a new wavelength component, called the idler wave, will be generated. Two problems for all kinds of FOPAs are the stimulated Brillouin scattering (SBS) effect that can limit the pump power, and the fact that the nonlinear fibers have a non-uniform dispersion. A method for suppressing the SBS and simultaneously controlling the dispersion is presented and evaluated. By using two pumps, flat and broadband gain can be achieved, but this is typically limited by the available pump wavelengths. The generation of a high-power pump outside the conventional wavelength range is demonstrated, and applied in a two-pump FOPA with very broadband gain. To operate in phase-sensitive mode, the FOPA requires the idler wave to be present at the input, and that all waves are phase-correlated. The use of a first stage based on FWM to achieve this is presented, and a second stage operating in phase-sensitive mode is characterized in terms of gain, and in another experiment, the unique phase-squeezing property was characterized using a coherent receiver. This property is also exploited to demonstrate all-optical phase regeneration of phase-encoded data

Phase-Sensitive Fiber-Optic Parametric Amplifiers and their Applications (Invited paper)

We review some fundamental and practical aspects of fiber-optic parametric amplifiers (FOPAs). In particular, their unique phase-sensitive amplification ability along with the corresponding ultralow noise figure will be discussed. Applications of both phase-insensitive and phase-sensitive FOPAs will also be covered

Optical modulation signal enhancement using a phase sensitive amplifier

We propose and demonstrate the use of a PSA as a modulation signal enhancer for the first time. It can generate both phase- and amplitude modulated signals from low-extinction inputs

Optical modulation signal enhancement using a phase sensitive amplifier

We propose and demonstrate the use of a PSA as a modulation signal enhancer for the first time. It can generate both phase- and amplitude modulated signals from low-extinction inputs

Phase-Sensitive Fiber-Optic Parametric Amplifiers and their Applications (Invited paper)

We review some fundamental and practical aspects of fiber-optic parametric amplifiers (FOPAs). In particular, their unique phase-sensitive amplification ability along with the corresponding ultralow noise figure will be discussed. Applications of both phase-insensitive and phase-sensitive FOPAs will also be covered

Phase and amplitude characteristics of a phase-sensitive amplifier operating in gain saturation

We investigate a non-degenerate phase-sensitive amplifier (PSA) operating in gain saturation experimentally and numerically using the three-wave model. The phase-dependent gain and phase-to-phase transfer functions are obtained for different levels of saturation with good agreement between experimental and numerical data when higher-order FWM is small. Moreover, we identify an operating point where the PSA is found to be able to significantly reduce both phase-and amplitude noise simultaneously

Impact of Zero-Dispersion-Wavelength Distributions on the Noise Figure Nonreciprocity of a Fiber Parametric Amplifier

For the first time we both theoretically and experimentally show that the zero-dispersion-wavelength (ZDW) variations in highly nonlinear fibers (HNLFs) will modify the output noise figure (NF) of a fiber optical parametric amplifier and make it nonreciprocal, due to the Raman phonon induced excess noise. The results show that a longer ZDW (but still below the pump wavelength) close to fiber input will give a better noise performance. The experimental results agree well with theory

Phase and Amplitude Transfer Functions of a Saturated Phase-Sensitive Parametric Amplifier

We experimentally investigate the phase and amplitude transfer functions of a nondegenerate idler PSA in saturation. A regime in which phase noise can be reduced with very low amplitude penalty is identified

Ultra-low-noise, Broadband Phase-Sensitive Optical Amplifiers and Their Applications

Frequency non-degenerate phase-sensitive amplifiers (PSAs) have the potential to realize broadband and noiseless amplification. However the rigorous requirement of phase- and wavelength-locking of the input waves has significantly hampered their progress. In this paper, we review recent research on this type of optical amplifier. This work is based on a copier-PSA scheme, which consists of a parametric phase-insensitive copier followed by one or more PSAs. Broadband gain and noise performance of a fiber-based non-degenerate PSA has been characterized, both theoretically and experimentally. A record-low 1.1 dB noise figure was measured at > 26 dB gain, and a clear phase dependent gain was observed. Moreover, potential applications including phase noise squeezing and ultra-low noise, multi-channel and modulation-format-transparent linear amplification with up to 6 dB link noise figure advantage over conventional EDFA-amplified links have been experimentally demonstrated. The prospects and practical challenges of this intriguing amplification technology are also discusse