Shimie Atkins

All-optical pulse rate multiplication using fractional Talbot effect and field-to- intensity conversion with cross-gain modulation

The authors show a passive all-optical method for pulse-rate multiplication. It is based on the fractional temporal Talbot effect along with nonlinear field-to-intensity conversion, using cross gain modulation in a semiconductor optical amplifier. In the experimental demonstration, the pulse rate was doubled and quadrupled to provide /spl sim/20-40-GHz pulses, but much higher rates can be obtained with this method.

Repetition-rate multiplication of optical pulses using uniform fiber Bragg gratings

A simple method for repetition-rate multiplication of optical pulses using uniform Bragg gratings is demonstrated. The grating formation system for this application requires positioning accuracy of only 1 μm. A simple method of control for each of the gratings in the writing process is proposed. Compensation of fiber dispersion using rate multiplication of pulses is also demonstrated.

Dispersion-mode pulsed laser

A new self-consistency condition in pulsed lasers with strong intracavity dispersion imposes dispersion modes with specific cavity-length dependent pulse rates, utilizing pulse-train self-imaging properties of a temporal Talbot effect. We give an experimental demonstration of such a laser operation, using a long fiber cavity. We also demonstrate temporal Talbot imaging of a train of short pulses that propagate along large distances of dispersive fibers.

Compression of periodic light pulses using all-optical repetition rate multiplication

We propose a novel method for compression of periodic optical pulses based on all-optical repetition rate multiplication of pulses without requiring propagation in a dispersive delay line. The compression principle is explained using the temporal Talbot effect. The proposed method is demonstrated experimentally with the generation of ∼20 ps pulses from cw radiation of a laser diode. The repetition rate multiplication is performed with fiber Bragg gratings. The proposed method simultaneously implements two important requirements of many fields, for example, of optical communications: pulse compression and pulse repetition rate multiplication.

Experimental demonstration of localization in the frequency domain of mode-locked lasers with dispersion

Mode-locked lasers with intracavity dispersion are experimentally shown to exhibit localization behavior in their frequency domain. The localization, with its typical exponential spectrum structure, is analogous to that which occurs for the quantum kicked rotor. The experimental demonstration of our optical kicked rotor is done with a long mode-locked dispersive fiber laser. The localization effect sets a basic limit on the spectrum bandwidth and the minimum pulse width in such lasers. It also provides a special experimental test bed for the study of optical kicked rotors and localization effects.

Repetition rate multiplication of optical pulses using fiber Bragg gratings

In this paper, a simple method for repetition rate multiplication of optical pulses using a number of fiber Bragg gratings is demonstrated, where the required positioning accuracy in the grating formation was only 1 /spl mu/m. The lack of narrow passbands in the proposed method, provides stability for the multiplied pulses. We propose a simple method of control for each of the gratings in the writing process. We also demonstrate the use of true repetition rate multiplication for compensation of fiber dispersion.

Fractional dispersion-modes in a pulsed fiber laser

We present and demonstrate pulse operation of a fiber laser at fractional dispersion modes. These modes are obtained when the applied modulation frequency of the laser is tuned to match the cavity round-trip to a fraction of the Talbot length. The laser pulse and spectrum behavior and the losses are determined by the repetition rate multiplying aspect of the fractional Talbot effect and the modulation parameters.

Evolution of localization in frequency for modulated light pulses in a recirculating fiber loop.

We present an experimental demonstration of the evolution of localization in frequency of light pulses that are repeatedly kicked by phase modulation and then propagated along equally spaced lengths of fiber with weak dispersion. The experiment was performed with a long fiber recirculating loop that allows us to follow the pulses spectral changes after each cycle.

Evolution of localization in frequency for modulated light pulses in a recirculating fiber loop

Summary form only given. We present an experimental demonstration of the evolution of localization in frequency of the optical kicked rotor in dispersive single mode fibers, predicted previously. This localization occurs after propagation in a dispersive fiber of broad light pulses that are repeatedly kicked by a sinusoidal RF phase modulation at equally spaced locations along the fiber. The naive expectation concerning the evolution of the spectrum and the buildup of sidebands (harmonics) is that their number diffusively increases with the number of kicks, so that the spectrum continuously broadens with propagation. However due to localization the spectrum is confined, usually with an exponential signature. The focus of the present paper is the transition between the broadening and the localization regimes, and the number of kicks needed for it. The experimental system to track the evolution of localization consisted of a recirculating fiber loop comprised of a tunable erbium doped fiber amplifier, a LiNbO/sub 3/ phase modulator, a chirped fiber Bragg grating (to minimize lasing of the system), polarization controls, and an electrooptic switch.

Compression of periodic optical pulses without propagation in dispersive delay line

Summary form only given. Conventional optical pulse compression is accomplished in two stages: first by performing quadratic phase modulation of the pulses and then propagating the modulated pulses through a dispersive delay line. We demonstrate a novel method of periodic pulse compression that does not require propagation of the pulses in a dispersive delay line. This method is based on the use of pulse repetition rate multiplication, and can be explained with the help of the temporal Talbot effect. The pulses were generated from cw radiation of a tunable laser diode. The phase modulated light was reflected from the fiber Bragg gratings and a circulator directed it to the measuring equipment. To obtain the desired pulses, fine tuning was required for the laser wavelength, the modulation frequency and the modulation index. Pulses obtained (with a rate multiplication M = 4) using four fiber Bragg gratings are shown. The original pulse repetition rate and modulation index were 6.25 GHz and 3.3 rad, respectively.