Search results for "photonics"
showing 10 items of 802 documents
Instantaneous frequency measurement by in-fiber 0.5th order fractional differentiation
2016
We experimentally demonstrate the possibility to retrieve the instantaneous frequency profile of a given temporal light pulse by in-fiber fractional order differentiation of 0.5th-order. The signal's temporal instantaneous frequency profile is obtained by simple dividing two temporal intensity profiles, namely the intensities of the input and output pulses of a spectrally-shifted fractional order differentiation. The results are supported by the experimental measurement of the instantaneous frequency profile of a mode-locked laser. Fil: Poveda-Wong, L.. Universidad de Valencia; España Fil: Carrascosa, A.. Universidad de Valencia; España Fil: Cuadrado Laborde, Christian Ariel. Consejo Nacion…
Experimental demonstration of fractional order differentiation using a long-period grating-based in-fiber modal interferometer
2016
In this work we demonstrate both, experimentally and theoretically, that a long-period grating-based in-fiber modal interferometer can perform an all-optical arbitrary-order fractional differentiation. Experimentally, we fractionally differentiated to the 0.5th order a secant hyperbolic-like pulse of 23 ps time width provided by a 1039.5 nm emission wavelength modelocked fiber laser, with a chirp parameter of −30. An analytical expression relating the fractional order of differentiation n with the characteristics of the modal interferometer was also derived, with the purpose to simplify the design procedure. The proposal was corroborated also numerically. This device may find applications i…
Linear and nonlinear fiber propagation of partially coherent fields exhibiting temporal correlations
2019
International audience; Using ultrafast photonic first-order differentiator applied on a partially coherent field, we report the generation of two correlated temporal waveforms and study their correlation properties upon linear and nonlinear propagation along the two orthogonal polarization axis of a dispersive optical fiber. Temporal correlations are maintained in linear propagation whereas Kerr nonlinearity generates anti-correlated temporal intensity patterns for both partially and uncorrelated fields. Experiments are in close agreement with the theoretical analysis.
Generalized modulational instability in multimode fibers: Wideband multimode parametric amplification
2015
In this paper intermodal modulational instability (IM-MI) is analyzed in a multimode fiber where several spatial and polarization modes propagate. The coupled nonlinear Schr\"odinger equations describing the modal evolution in the fiber are linearized and reduced to an eigenvalue problem. As a result, the amplification of each mode can be described by means of the eigenvalues and eigenvectors of a matrix that stores the information about the dispersion properties of the modes and the modal power distribution of the pump. Some useful analytical formulas are also provided that estimate the modal amplification as function of the system parameters. Finally, the impact of third-order dispersion …
Demonstration of polarization pulling using a fiber-optic parametric amplifier
2012
International audience; We report the observation of all-optical polarization pulling of an initially polarization-scrambled signal using parametric amplification in a highly nonlinear optical fiber. Broadband polarization pulling has been achieved both for the signal and idler waves with up to 25 dB gain using the strong polarization sensitivity of parametric amplifiers. We further derive the probability distribution function for the final polarization state, assuming a randomly polarized initial state, and we show that it agrees well with the experiments.
All-Optical Tuning of WGMs in Microspheres Made of Er/Yb Codoped Optical Fiber
2014
All-optical, pump-assisted, thermal tuning of high-Q whispering-gallery mode (WGM) resonances of microspheres is demonstrated. The microspheres were made of an Er/Yb codoped single-mode silica optical fiber. The pump light absorbed by the active ions heats the microsphere, which leads to the shift of the resonances. A tuning range in excess of 2 nm in the C-band is achieved. The presence of active ions is restricted to the core of the microsphere. The WGM fields, which are confined in a region close to the surface of the microsphere, do not overlap with the dopant. Thus, high-Q resonances (>10 7 ) are achieved, as in pure silica microspheres, even at optical wavelengths within the absorptio…
Effect of wavelength dependence of nonlinearity, gain, and dispersion in photonic crystal fiber amplifiers
2005
Photonic crystal fibers are used in fiber amplifiers and lasers because of the flexibility in the design of mode area and dispersion. However, these quantities depend strongly on the wavelength. The wavelength dependence of gain, nonlinearity and dispersion are investigated here by including the wavelength dependence explicitly in the nonlinear Schr\"odinger equation for photonic crystal fibers with varying periods and hole sizes. The effect of the wavelength dependence of each parameter is studied separately as well as combined. The wavelength dependence of the parameters is shown to create asymmetry to the spectrum and chirp, but to have a moderating effect on pulse broadening. The effect…
Demonstration of Stimulated-Raman-scattering suppression in optical fibers in a multifrequency pumping configuration
1999
International audience; We analyze the stimulated-Raman-scattering-(SRS) process induced by a linearly polarized multifrequency pump field in a normally dispersive single-mode fiber. We show, by theoretical analysis and numerical simulations, that the SRS process may be either controlled by switching all the generated Stokes radiations to the lowest-frequency pump or suppressed for all the frequency components of the pump field. The suppression process is achieved by an appropriate choice of the frequency separation between the pumps and a particular power distribution among the frequency components of the pump field. We present experimental spectra showing the effectiveness of this suppres…
Cascadability and reshaping properties of a saturable absorber inserted inside a RZ transmission line for future 160-Gbit/s all-optical 2R-regenerato…
2007
International audience; In this prospective work, we analyze the behavior of a quantum-well microcavity saturable absorber component cascaded into a 100-km SMF RZ transmission line in order to annihilate the ghost-pulse phenomenon in the following simplified “...010101...” 160-Gbit/s 2-bit pattern at 1555 nm. Recirculating-loop experiments show a maximal ghost-pulse extinction up to 11.6 dB as well as an intensity extinction ratio enhancement higher than 6 dB over at least 800 km of propagation.
Q switching and mode locking pulse generation from an all-fiber ring laser by intermodal acousto-optic bandpass modulation
2018
Q-switched and mode-locked (QML) pulse generation from an all-fiber ring laser based on intermodal acousto-optic bandpass modulation is reported. The modulator relies on full-acousto-optic mode re-coupling cycle induced by a standing flexural acoustic wave, with a transmission response that is controlled by amplitude modulation of the acoustic wave signal. The Q factor of the cavity is controlled by a rectangular pulse wave with variable frequency and duty cycle, whereas mode locking is achieved by amplitude modulation derived from a standing flexural acoustic wave. The best QML pulses were obtained at 0.5 kHz repetition rate, with a pump power of 549.2 mW, at the optical wavelength of 1568…