Search results for " Modulation"

Frequency tunable polarization and intermodal modulation instability in high birefringence holey fiber

2009

International audience; We present an experimental analysis of polarization and intermodal noise-seeded parametric amplification, in which dispersion is phase matched by group velocity mismatch between either polarization or spatial modes in birefringent holey fiber with elliptical core composed of a triple defect. By injecting quasi-CW intense linearly polarized pump pulses either parallel or at 45 degrees with respect to the fiber polarization axes, we observed the simultaneous generation of polarization or intermodal modulation instability sidebands. Furthermore, by shifting the pump wavelength from 532 to 625 nm, we observed a shift of polarization sidebands from 3 to 8 THz, whereas int…

Raman-assisted parametric frequency conversion in a normally dispersive single-mode fiber

1999

International audience; We demonstrate efficient frequency conversion with large frequency shifts of an anti-Stokes signal into a parametrically seeded Stokes idler, which is generated by a highly mismatched three-wave mixing interaction and subsequent Raman amplification in a normally dispersive single-mode fiber. The use of non-phase-matched waves in Raman-assisted three-wave mixing interactions overcomes the strict spectral limitations imposed by phase-matching conditions in parametric frequency-conversion processes.

Supercontinuum generation in silicon waveguides based on optical wave-breaking

2014

We theoretically find the third order dispersion that optimizes the spectral broadening induced by optical wave-breaking. It produces supercontinuum spectra spanning beyond 2=3 of an octave in a silicon waveguide pumping at 1550 nm.

Metalenses with high-NA, enhanced resolution and apodization

2017

Dielectric microlenses employed in imaging and focusing for optoelectronics are currently prospects to be substituted by metalenses showing an extraordinary optical performance within notably reduced volumes. Here we present some proposals to achieve an enhanced resolution in metallodielectric metasurface-based lenses established on either efficient arrangements with high numerical aperture or spatial filtering enabling to surpass the limit of resolution derived by the Rayleigh criterion.

Phase-shifting digital lensless Fourier holography for high numerical aperture in-line interferometric microscopy

2012

A new common-path and phase-shifting digital lensless Fourier architecture for high numerical aperture (NA) imaging in lensless in-line holographic microscopy based on the use of a spatial light modulator (SLM) is presented and experimentally validated.

Monitoring Reversible Tight Junction Modulation with a Current-Driven Organic Electrochemical Transistor

2021

All-fiber lasers actively modelocked by acousto-optic modulation

2010

The development of all-fiber lasers is of high interest because of the intrinsic robustness, compactness and energy efficiency. In-fiber amplitude modulators based on acousto-optic modulation of fiber Bragg gratings (FBG) permit the implementation of novel all-fiber actively modelocked lasers. Using either traveling or standing longitudinal acoustic waves, optical pulses between 500 and 100 mW peak powers and ∼ 700 ps temporal width were obtained at 4.1 and 9 MHz repetition rates, respectively. Implementing a simultaneous active Q-switching, we have demonstrated a doubly active Q-switching and mode-locking of two different all-fiber laser configurations. In the case of the laser based on tr…

Characterization of a 10Hz double-pulse non-normal incidence pumped transient collisional Ni-like molybdenum soft x-ray laser for applications

2009

Stable and reliable operation of a nickel-like molybdenum transient collisional soft x-ray laser at 18.9 nm demonstrated and studied with a 10Hz Ti:sapphire laser system proves the suitability of the double-pulse non-normal incidence pumping geometry for table-top high repetition soft x-ray lasers and broadens the attractiveness of x-ray lasers as sources of coherent radiation for various applications. X-ray laser emission with pulse energies well above 1 μJ is obtained for several hours at 10Hz repetition-rate without re-alignment under optimized double pumping pulse parameters including energy ratio, time delay, pulse duration and line focus width.

Long-cavity all-fiber ring laser actively mode locked with an in-fiber bandpass acousto-optic modulator.

2013

We demonstrate low-frequency active mode locking of an erbium-doped all-fiber ring laser. As the mode locker, we used a new in-fiber bandpass acousto-optic modulator showing 74% modulation depth, 3.7 dB power insertion losses, 4.5 nm of optical bandwidth, and 20 dB of nonresonant light suppression. The laser generates 330 ps mode-locked pulses over a 10 ns pedestal, at a 1.538 MHz frequency, with 130 mW of pump power. Fil: Cuadrado Laborde, Christian Ariel. Universidad de Valencia; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigaciones Opticas (i); Argentina. Provincia de Buenos Aires. Gobernación. Comisión de In…

High-repetition rate acoustic-induced Q-switched all-fiber laser

2005

We report a high repetition rate actively Q switched all fiber laser. The acousto optic interaction controls the cou pling between co propagating core and cladding modes and is used to modulate the optical losses of the cavity, which permits to perform active Q-switching. Using 1.4 m of 300 ppm Er-doped fiber and a maximum pump power of 120 mW, we have obtained up to 1 W peak power pulses, with a pulse repetition rate that can be continuously varied from 1 Hz to 120 kHz and a pulse width that changes from 70 ns to 2.2 μs.