Evgeny Shumakher

Large tunable delay with low distortion of 10 Gbit/s data in a slow light system based on narrow band fiber parametric amplification

We describe slow light propagation of a 10 Gbit/s data stream in a narrow band fiber parametric amplifier. A large tunable delay of 10 to 60 ps with very low signal distortion has been demonstrated in a 1 km long dispersion shifted fiber. The longitudinal variation of the fiber propagation parameters was extracted from measured amplified spontaneous emission and these parameters serve to accurately predict the delayed temporal pulse shape. Simulated results suggest that the system exhibits large delays with low distortions in a wide spectral range within the OPA gain spectrum.

A Novel Multiloop Optoelectronic Oscillator

We present a novel realization of a multiloop optoelectronic oscillator based on a wavelength multiplexed optical source and fiber Bragg grating reflectors. The oscillator exhibits a phase noise of -108 dBc/Hz at 10-kHz offset from the 10.2-GHz carrier while suppressing parasitic modes to below -80 dBc.

On the balance between delay, bandwidth and signal distortion in slow light systems based on stimulated Brillouin scattering in optical fibers

We describe systematic measurements of the gain and delay spectra in a slow light system based on stimulated Brillouin scattering in optical fibers. The measurements yield the system complex transfer function with which delays and signal distortion can be calculated for any input signal. The theoretical predictions are confirmed experimentally for single pulses as well as 50 Mb/s data streams in a system which employs pump modulation to modify the gain and delay spectra of the SBS process.

Optoelectronic Oscillator Tunable by an SOA Based Slow Light Element

We present a continuously tunable optoelectronic oscillator with an intra cavity slow light element based on coherent population oscillations in a semiconductor optical amplifier. The performance of the oscillator is characterized in terms of its frequency tuning range and phase noise. These two characteristics can be traded for each other by choosing the operating conditions of the slow light element and the oscillator fiber length.

Fiber parametric oscillator for the 2 μm wavelength range based on narrowband optical parametric amplification.

We describe a widely tunable synchronously pumped coherent source based on the process of narrowband parametric amplification in a dispersion-shifted fiber. Using an experimental fiber with a zero-dispersion wavelength of 1590 nm and pump wavelengths of 1530 to 1570 nm yields oscillations at 1970 to 2140 nm-the longest reported wavelength for a fiber parametric oscillator. The long-wavelength oscillations are accompanied by simultaneous short-wavelength oscillations at 1200 to 1290 nm. The parametric gain is coupled to stimulated Raman scattering. For parametric oscillations close to the Raman gain peak, the two gain processes must be discriminated from each other. We devised two configurations that achieve this discrimination: one is based on the exploitation of the difference in group delay between the wavelengths where Raman and parametric gain peak, and the other uses intracavity polarization tuning.

On the Roles of Polarization and Raman-Assisted Phase Matching in Narrowband Fiber Parametric Amplifiers

This paper presents a comprehensive framework for the analysis of narrowband optical fiber parametric amplifiers. The novel vector model comprises virtually every significant nonlinear contribution, including a full stimulated Raman interaction model. We employ the model to calculate the influence of fiber random birefringence, as well as of longitudinal variations of linear and nonlinear propagation parameters on both gain and phase spectra.

Signal-to-noise ratio of a semiconductor optical-amplifier-based optical phase shifter

We report an experimental characterization of additive noise from a single-stage phase shifter based on slow and fast light propagation in a bulk semiconductor optical amplifier. We examine the influence of redshifted sideband suppression and optical input power on the signal-to-noise ratio (SNR) of the detected signal. We conclude that in spite of the up to a 6 dB reduction in the detected noise, the SNR remains dominated by the decrease in the detected signal power.

Self-starting ultralow-jitter pulse source based on coupled optoelectronic oscillators with an intracavity fiber parametric amplifier

A self-starting optical pulse source based on mutually coupled optoelectronic oscillators is described. The system employs a phototransistor-based microwave oscillator that is coupled to a fiber cavity optoelectronic oscillator with an intracavity fiber parametric amplifier. It self-starts and exhibits 3 ps pulses at a rate of 10 GHz with extremely low jitter of 30, 29, and 40 fs (for integration bandwidths of 100 Hz-15 kHz, 500 Hz-1 MHz, and 100 Hz-1 MHz, respectively).

Noise Properties of Microwave Phase Shifters Based on Semiconductor Optical Amplifiers

In this paper, we present detailed modeling and experiments of the noise properties of a single-stage microwave phase-shifting element based on slow light propagation in a semiconductor optical amplifier. A wideband large-signal model is used to calculate the performance dependencies on gain, input power, and modulation frequency for the case where the red-shifted sideband at the amplifier output is suppressed.

The role of optical filtering in microwave phase shifting

We highlight the importance of the delay arising from optical filters in slow-light-based microwave phase shifting systems. We calculate the filter delay numerically from the measured amplitude response by using the well-known Kramers-Kronig relations. The complex filter transmission response is then incorporated within a numerical model with which we explain phase shifting results obtained from experiments employing semiconductor optical amplifiers as slow light elements.