Eugene Frumker

Femtosecond pulse shaping using a two-dimensional liquid-crystal spatial light modulator.

We introduce a programmable, high-rate scanning femtosecond pulse shaper based on a two-dimensional liquid crystal on a silicon spatial light modulator (SLM). While horizontal resolution of 1920 addressable pixels provides superior fidelity for generating complex waveforms, scanning across the vertical dimension (1080 pixels) has been used to facilitate at least 3 orders of magnitude speed increase as compared with typical liquid-crystal SLM-based pulse shapers. An update rate in excess of 100 kHz is demonstrated.

Femtosecond pulse-shape modulation at nanosecond rates.

We report high-rate, computer-controlled femtosecond pulse shaping by use of an electro-optical gallium arsenide optical phased-array modulator with 2304 controlled waveguides. It provides fast modulation speed of both spectral phases and amplitudes. Limited by the driving electronics of our current setup, we were able to update a pulse shape in approximately 30 ns. This technique paves the way toward individual shaping of every single pulse of typical femtosecond mode-locked oscillators.

Phase and amplitude pulse shaping with two-dimensional phase-only spatial light modulators

We consider a programmable, phase, and amplitude femtosecond pulse shaper based on a two-dimensional (2D) reflective liquid-crystal (LC) spatial light modulator (SLM). A new zero-order pulse shaping scheme is introduced and compared to the first-order scheme, both theoretically and experimentally, using liquid crystal on silicon 2D SLM. While the spectral components of the pulse are spread across the horizontal dimension, we use the vertical direction for modulation of both spectral phases and amplitudes. It was found that while zero-order approach provided better light efficiency (67% versus 43%), the first-order scheme has superior dynamic range of amplitude modulation.

Femtosecond pulse-shape modulation at kilohertz rates

We demonstrate a new scanning femtosecond pulse-shaping technique that allows pulse shapes to be modulated at kilohertz rates. This technique is particularly useful for lock-in measurements in which the signal is synchronized with the alternating pulse shapes. The pulse-shape lock-in technique is demonstrated in resonant coherent anti-Stokes Raman scattering, where it is shown to significantly improve the ratio of the resonant signal to both the nonresonant background and to noise.

Generic method for aero-optic evaluations

The effect of aerodynamic flow on the performance of an airborne optical system is becoming a critical issue in the development of electro-optic systems. A novel technique for aero-optic calculations that is based on commercially available software is presented. The optically relevant data from the computational fluid dynamics results are transformed into an index-of-refraction field and introduced as an input to the optical code. The data do not necessarily have to be presented in analytical form; instead it is introduced in a most general form as a discrete set of values located at a nonuniform grid of points. The modified quadratic Shepard method has been adopted for data interpolation, enabling a simple interface with virtually any software output. Several numerical simulations that demonstrate the technique are presented.

Femtosecond pulse shaping using a 2D liquid crystal spatial light modulator

We demonstrate a new scanning femtosecond pulse shaping technique that enables modulation of pulse- shapes at hundred of kilohertz rates. This technique is particularly useful for lock-in on the pulse shape measurements.

Discrete nonlinear X-waves in waveguide arrays

We present experimental evidence for the formation of nonlinear X-waves in AlGaAs waveguide arrays. These results agree with numerical simulations based on the discrete nonlinear Schrodinger equation with an appropriate temporal dispersion term.

Excitation of discrete X-waves in nonlinear waveguide arrays

We present experimental evidence for the formation of X-waves in nonlinear AlGaAs waveguide arrays. These results agree with numerical simulations based on the discrete nonlinear Schrodinger equation with an appropriate temporal dispersion term

Spatio-temporal Effects in Nonlinear Discrete Media

In this paper, we will introduce the concept of discrete solitons and we will discuss some of their spatio-temporal dynamics, which leads to interesting consequences in both the fundamental and the applied domain