Nonlinear Fiber Amplifier Research Articles

Active spectral phase control by use of an acousto-optic programmable filter in high-repetition-rate sub-80 fs nonlinear fiber amplifiers

We report the generation of sub-80 fs pulses with energy in the 100 nJ range at 1050 nm and a repetition rate up to 164 kHz based on a nonlinear fiber amplification system combined with an active control of the spectral phase. This control is performed by an acousto-optic programmable dispersive filter operated at a multiple of its acoustic repetition rate. This result opens up its possible use in highly nonlinear fiber chirped-pulse amplification setups.

Similaritons in nonlinear optical systems

By using the lens-type transformation, exact soliton and quasi-soliton similaritons are found in (1+1), (2+1) and (3+1)-dimensional nonlinear Schrödinger equations in the context of nonlinear optical fiber amplifiers and graded-index waveguide amplifiers. The novel analytical and numerical results show that, in addition to the exact solitonic optical waves, quasi-solitonic optical waves with Gaussian, parabolic, vortex and ring soliton profiles can evolve exact self-similarly without any radiation.

Theory of parabolic pulse propagation in nonlinear dispersion-decreasing optical fiber amplifiers

We show that pulse spectral broadening in normally dispersive nonlinear fiber amplifiers may be enhanced by introducing a suitable dispersion tapering. We obtain an analytical dispersion profile that permits one to reduce pulse propagation in a varying dispersion fiber to the case of an equivalent fiber with constant parameters.

Theoretical optimization of nonlinear chirped-pulse fiber amplifiers

The exploitation of nonlinear phase shifts (ΦNL) in chirped-pulse fiber amplifiers has been demonstrated recently. Systematic optimization of the performance of a femtosecond-pulse fiber amplifier in the presence of substantial ΦNL is a challenging multivariable problem. We introduce an approximate theoretical model that is valid as long as the ΦNL is not so large that the spectrum changes substantially. The model allows an arbitrary chirped-pulse amplification system to be described by a set of four universal curves. These reveal the scaling of performance and allow determination of the optimal values of residual group-velocity dispersion and third-order dispersion for a given pulse duration and energy.

Output Phase Characteristics of a Nonlinear Regenerative Fiber Amplifier

A simple regenerative fiber amplifier with a nonlinear refractive index is described and analyzed. Using standard equations of operation, we model the circulating intensity within the resonant cavity and determine the nonlinear phase response to changes in this intensity over the entire range of initial cavity detuning. Simple stability criteria are established and described. It is shown that the presence of sufficient nonlinearity leads to stable regions of operation with consistent phase-intensity relationships. Based on these results, the phase of the amplifier output is predicted relative to the injected field for the entire range of initial detuning

Analytical Dynamics of Parabolic Pulses in Nonlinear Optical Fiber Amplifiers

The process of attraction of parabolic pulses towards a self-similar profile in weakly dispersive nonlinear fiber-optic amplifiers can be well described by means of a simple analytical model. This approach permits for a rapid evaluation of the achievable pulse compression factor of high energy, strongly chirped pulses that emerge from a fiber amplifier

High spectral power density supercontinuum generation in a nonlinear fiber amplifier

We present an experimental study on supercontinuum generation with high spectral power density by using a commercial nonlinear fiber amplifier. This new approach consists in the simultaneous combination of the amplification of a pulsed seed signal at 1.06 microm and its peak-power-induced spectral broadening as the optical pulse propagates along the amplifying fiber. A 750-nm broadening from 1 microm to 1.75 microm with tunable spectral power density according to the amplifier gain level is obtained. Spectral power density in excess of 3 mW/nm is demonstrated.

Scalar off-resonant modulation instability in rare-earth-doped fiber amplifiers

Presents an analytical model which describes the dynamics of the modulation instability in a nonlinear, dispersive, homogeneously broadened and nonsaturable fiber amplifiers. The general case of arbitrary detuning between the laser frequency and the resonance frequency and arbitrary bandwidth of the amplifying transition is treated. The model accounts both for the gain dispersion and for the gain-induced, near resonant refractive index dispersion, Simple closed form expressions for the combined gain coefficients of the Stokes and anti-Stokes frequencies are obtained.