Intensity Modulation Transfer Research Articles

Fiber optical parametric amplified optical direct-detection OFDM signal with intensity modulation transfer blocking.

A fiber optical parametric amplified optical orthogonal frequency division multiplexing (OFDM) signal with intensity modulation transfer (IMT) blocking is proposed. A novel blank carrier blocking method is adopted to suppress pump to signal intensity interference. Compared with regular optical signal, the IMT induced interference can be well blocked in the experiment. The error vector magnitude (EVM) and signal gain are also investigated in the experiment.

All-Optical DPSK Regenerative One-to-Nine Wavelength Multicasting Using Dual-Pump Degenerate Phase Sensitive Amplifier

We present theoretical investigation of all-optical differential phase-shift keying (DPSK) regenerative wavelength multicasting using dual-pump degenerate phase sensitive amplifier (PSA), based on seven-wave model rather than traditional three-wave model. We first test the accuracy of the seven-wave model in the context of 40 Gb/s DPSK all-optical regenerative multicasting. We find that the seven-wave model is more accurate than the three-wave model. Meanwhile, we successfully optimize optical signal power, frequency spacing between two pumps, and regeneration capability of all multicasting channels. All-optical DPSK regenerative one-to-nine wavelength multicasting can be successfully realized. Both eye diagrams and the calculated bit error rate curve demonstrate that the optical signal to noise ratio penalties of all multicasting channels are improved by around 3 dB. Finally, to the best of our knowledge, we investigate, for the first time, the effects of the high-order four-wave mixing (FWM) products on the evolution of pump-to-signal intensity modulation transfer (IMT) and IMT from the pump to all wavelength-multicasting channels in a dual-pump degenerate PSA. We find that high-order FWM products contribute to the suppression of pump-to-signal IMT after proper optimization of dual-pump's frequency spacing and signal optical power. Both regenerative one-to-nine wavelength multicasting and pump-to-signal IMT smaller than 1 can be simultaneously achieved under the gain saturation region.

Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our knowledge, how gain saturation of a FOPA reduces the noise contribution due to the transfer of pump power fluctuations to the signal. In a particular example, it is shown that the transferred noise is significantly reduced by a factor of 3, while the FOPA gain remains above 10 dB.

Pump-To-Signal Intensity Modulation Transfer Characteristics in FOPAs: Modulation Frequency and Saturation Effect

This paper reports a comprehensive study of pump-to-signal intensity modulation transfer (IMT) in single-pump fiber optic parametric amplifiers (FOPAs). In particular, the IMT is studied for the first time for high-frequency fluctuations of the pump as well as in the saturated gain regime. The IMT cut-off frequency in typical single-pump FOPAs is around 100-200 GHz. The possibilities to shift this frequency based on dispersion and nonlinearities involved in the parametric gain are discussed. The severe IMT to the signal at low modulation frequencies can be suppressed by more than 50% in the gain saturation regime with respect to the linear gain operation. Experimental results confirm the validity of the numerical study.

Complex intensity modulation transfer function for supercontinuum generation in microstructure fibers

We investigated the complex intensity modulation transfer function for supercontinuum generation in microstructure fibers (MSF). We measured the relative intensity and phase modulations in the output spectrum of the MSF with spectral resolution of one and ten nanometers, respectively. For small intensity modulation indices (~ 1 %) we found power modulation gain factors as large as 100 in certain spectral areas of the super continuum. In all spectral regions the phase modulation coefficient was found not to exceed 40 rad per percent of pulse power change. Consequences for applications of phase-coherent supercontinua, such as frequency metrology, pulse synthesis, heterodyne coherent anti-Stokes Raman scattering (CARS) are discussed.

Polarization dependence of the intensity modulation transfer function of an optical system with PMD and PDL

The intensity modulation transfer function of a linear optical system is described using a time-dependent Muller-like matrix. Based on this description a novel measurement method for the combined effect of polarization mode dispersion and polarization-dependent loss is introduced.

An Intensity MTF Theory for Coherent Imaging

The effect that any parameter of a holographic or coherent imaging system would have on the resultant image is normally described by an amplitude modulation transfer function. We show here that an intensity modulation transfer function (MTF) can be used to analyze the coherent systems if diffuse targets are employed and if the usable area image.