Search results for "Photonics"
showing 10 items of 802 documents
Application of WGM Resonances to the Measurement of the Temperature Increment of Ho and Ho-Yb Doped Optical Fibers Pumped at 1125 and 975 nm
2021
Optical fiber characterization using whispering gallery mode resonances of the fiber itself has been demonstrated to be a powerful technique. In this work, we exploit the thermal sensitivity of whispering gallery mode resonances to characterize the pump-induced temperature increment in holmium doped and holmium-ytterbium codoped optical fibers. The technique relies on the measurement of the resonances’ wavelength shift due to temperature variation as a function of the pump power. Holmium doped fibers were pumped to the second excited level 5I6 of the Ho3+ ion using a laser diode at 1125 nm and ytterbium-holmium codoped fibers to the 2F5/2 level of the Yb3+ ion by a laser diode at 975 nm. Ou…
Spectroscopic response and charge transport properties of CdZnTe detectors grown by the vertical Bridgman technique
2015
In this work, we present the results of spectroscopic investigations on CdZnTe (CZT) detectors grown by the boron oxide encapsulated vertical Bridgman technique (1MEM-CNR, Parma, Italy). The detectors, with different thicknesses (1 and 2.5 mm), are characterized by the same electrode layout (gold electroless contacts): the anode is a central electrode (2 x 2 mm(2)) surrounded by a guard-ring electrode, while the cathode is a planar electrode covering the detector surface (4.1 x 4.1 mm(2)). The results of electrical investigations point out the low leakage currents of these detectors even at high bias voltages: 38 nA/cm(2) (T = 25 degrees C) at 10000 V/cm. The time stability and the spectros…
All-optical extinction-ratio enhancement of a 160 GHz pulse train by a saturable-absorber vertical microcavity
2006
International audience; A vertical-access passive all-optical gate has been used to improve the extinction ratio of a 160 GHz pico-second pulse train at 1555 nm. An extinction ratio enhancement of 6 dB is observed within an 8 nm bandwidth. Such a device is a promising candidate for low-cost all optical reamplication and reshaping (211) regeneration at 160 Gbits/s.
Near-field spectroscopy of low-loss waveguide integrated microcavities
2006
International audience; A scanning near-field spectroscopy method is used to observe loss reduction and Q-factor enhancement due to transverse-mode profile matching within photonic-crystal microcavities. Near-field measurements performed directly on cavity modes are compared with three-dimensional calculations and quantitative agreement is observed. (c) 2006 American Institute of Physics.
Rains of Solitons in a Fiber Laser
2009
We report a novel and intriguing nonlinear dynamics observed in a fiber laser cavity, in which soliton pulses are created from an extended noisy background and drift until they reach a condensed phase comprising several tens of aggregated solitons. This soliton flow can be adjusted with manual cavity tuning, and can even be triggered by the injection of an external low-power cw laser.
Experimental demonstration of 160-GHz densely dispersion-managed soliton transmission in a single channel over 896 km of commercial fibers
2003
International audience; We experimentally demonstrate the first 160-GHz densely dispersion-managed soliton transmission in a single channel at 1550 nm over nearly 900 km using commercially available non-zero dispersion-shifted fibers. This performance has been achieved by using a 16 km-long recirculating loop configuration and an appropriate design of the dispersion map.
Shaping Light in Nonlinear Optical Fibers
2017
International audience; This book is a contemporary overview of selected topics in fiber optics. It focuses on the latest research results on light wave manipulation using nonlinear optical fibers, with the aim of capturing some of the most innovative developments on this topic. The book’s scope covers both fundamentals and applications from both theoretical and experimental perspectives, with topics including linear and nonlinear effects, pulse propagation phenomena and pulse shaping, solitons and rogue waves, novel optical fibers, supercontinuum generation, polarization management, optical signal processing, fiber lasers, optical wave turbulence, light propagation in disordered fiber medi…
Generation of a 160-GHz transform-limited pedestal-free pulse train through multiwave mixing compression of a dual-frequency beat signal.
2002
International audience; We report the experimental generation of a 160-GHz picosecond pulse train at 1550 nm, using multiple four-wave mixing temporal compression of an initial dual-frequency beat signal in the anomalous-dispersion regime of a nonzero dispersion-shifted fiber. Complete intensity and phase characterizations of the pulse train were carried out by means of a frequency-resolved optical gating technique, showing that 1.27-ps transform-limited pedestal-free Gaussian pulses were generated.
All-fibered high-quality low duty-cycle 160-GHz femtosecond pulse source
2008
International audience; In this paper, we report the experimental demonstration of an all-optical fiber-based 160-GHz femtosecond pulse source exhibiting a duty cycle as low as 1/17. The 380-fs wellseparated Gaussian pulses are generated thanks to the strong temporal compression of an initial beat-signal propagating into three distinct segments of optical fiber. Experimental results are supported by numerical simulations based on the generalized nonlinear Schrödinger equation. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Far-field imaging of the electromagnetic local density of optical states.
2008
International audience; We introduce a new experimental method to measure the local electromagnetic density of states (LDOS) by integrating the differential scattering cross section. The signal detected essentially reflects the intrinsic scattering response of the photonic structures and renders the partial LDOS dominated by evanescent modes. We give a theoretical understanding of the LDOS image formation and show a qualitative agreement between experimental images and theoretical maps. This approach can be practically applied to the direct measurement of an optical antenna's scattering efficiency and can provide valuable information for designing optimum structures utilized in radiative de…