Search results for "photonics"
showing 10 items of 802 documents
Modulation transfer function of a toric intraocular lens: evaluation of the changes produced by rotation and tilt.
2011
PURPOSE: To evaluate the changes in optical quality when toric intraocular lenses (IOL) are rotated or tilted and to demonstrate that IOL rotation produces an increasing effect of aberrations. METHODS: Modulation transfer function (MTF) and average modulation were used to analyze the image quality of a toric IOL. The axis of the toric IOL was rotated 5°, 10°, 15°, 20°, 25°, and 30° in successive MTF measurements. The tilt values were 0° to 5°, in increments of 1°, plus a tilt of 15°. Pupil diameters of 3 and 5 mm were used. RESULTS: The MTF decay due to aberrations was more sensitive to rotation than tilt. The main decrement in the average modulation, of approximately 50% in both pupils, o…
“Nonlocal” dispersion cancellation with classical light
2009
Nonlocal dispersion cancellation [1] is a quantum phenomenon that relies on the use of a quantum light source, e.g., spontaneous parametric down-conversion (SPDC), providing temporally entangled photon pairs. Each photon in the pair propagates through a dispersive medium [see Fig. 1 (a)]. Under suitable conditions the dispersion of one photon cancels out the dispersion of the other photon, so that their intensity coincidence probability remains unchanged. Nonlocal dispersion cancellation has been experimentally demonstrated [2] and this phenomenon has subsequently triggered important applications in quantum information science, such as quantum-optical coherence tomography, distant clock syn…
Hilbert-Huang single-shot spatially multiplexed interferometric microscopy.
2018
Hilbert-Huang single-shot spatially multiplexed interferometric microscopy (H2S2MIM) is presented as the implementation of a robust, fast, and accurate single-shot phase estimation algorithm with an extremely simple, low-cost, and highly stable way to convert a bright field microscope into a holographic one using partially coherent illumination. Altogether, H2S2MIM adds high-speed (video frame rate) quantitative phase imaging capability to a commercially available nonholographic microscope with improved phase reconstruction (coherence noise reduction). The technique has been validated using a 20×/0.46 NA objective in a regular Olympus BX-60 upright microscope for static, as well as dynamic…
Propagation, Stability and Interactions of Novel Three-Wave Parametric Solitons
2006
International audience; We found a new class of analytic soliton solutions that describe the parametric wave mixing of optical pulses in quadratic nonlinear crystals. We analyze the stability properties, interactions and collisions of these solitons.
Challenges with balancing excitations in intermediate-band solar cells
2015
New insight into the potential of practical solar cells can be given through alternative modeling approaches like Monte Carlo simulations. In the present work, the performance of intermediate band solar cells was examined by this method. It is demonstrated that the balance of excitations from the valence band to the intermediate band and from the intermediate band to the conduction band is of great importance for the performance of such cells. Several cases with different distributions of photons given by ASTM standards have been employed in order to detect spectrum sensitivity. Incident photons are accounted for as they interact with the electrons in the valence band or in the intermediate…
All-fiber incoherent frequency-to-time mapping method for microwave signal generation with baseband transmission and multicasting support
2008
We present a proof-of-principle experiment for achieving simultaneous distribution of baseband radio-frequency data and up-conversion with broadcasting support over a passive optical network. The technique is based on an incoherent frequency-to-time mapping method for pulse shaping. Specifically, we synthesize the spectral density function of sliced ASE noise from an EDFA with a periodic Mach-Zehnder fiber interferometer optical filter. By using external intensity modulation combined with propagation in an optical fiber, after photodetection, the resultant averaged temporal pulse profile resembles the shape of the incoherent source. The photodetected signal contains both the baseband data a…
Gain Dynamics after Ultrashort Pulse Trains in Quantum Dot based Semiconductor Optical Amplifiers
2007
We study the gain dynamics in QD-based SOAs after excitation with fs-pulse trains of up to THz repetition rates. A complete ground-state gain recovery is found for 200 GHz repetition rates and injection currents around 90 mA.
Soliton topology versus discrete symmetry in optical lattices
2005
We address the existence of vortex solitons supported by azimuthally modulated lattices and reveal how the global lattice discrete symmetry has fundamental implications on the possible topological charges of solitons. We set a general ``charge rule'' using group-theory techniques, which holds for all lattices belonging to a given symmetry group. Focusing in the case of Bessel lattices allows us to derive also a overall stability rule for the allowed vortex solitons.
Incoherent photonic techniques for RF-AWG
2010
The capabilities for RF-AWG in terms of waveform fidelity for three different incoherent photonic methods are revised and discussed: incoherent frequency-to-time mapping, incoherent MWP filtering with N discrete taps, and multi-wavelength pulse compression.
1 Tb/s·km WDM transmission over multimode fibre link
2008
We demonstrate 1 Tb/smiddotkm WDM error-free transmission (highest reported value to our knowledge) over a MMF link by a combination of low-linewidth lasers and central launch.