99 research outputs found
Control of the Onset of Filamentation in Condensed Media
Propagation of intense, ultrashort laser pulses through condensed media like
crystals of BaF and sapphire results in the formation of filaments. We
demonstrate that the onset of filamentation may be controlled by rotating the
plane of polarization of incident light. We directly visualize filamentation in
BaF_2 via six-photon absorption-induced fluorescence and, concomitantly, by
probing the spectral and spatial properties of white light that is generated.Comment: To appear in Phys. Rev.
A fiber-integrated quantum memory for telecom light
We demonstrate the storage and on-demand retrieval of single-photon-level
telecom pulses in a fiber cavity. The cavity is formed by fiber Bragg gratings
at either end of a single-mode fiber. Photons are mapped into, and out of, the
cavity using quantum frequency conversion driven by intense control pulses. In
a first, spliced-fiber, cavity we demonstrate storage up to 0.55s (11
cavity round trips), with % total memory efficiency, and a
signal-to-noise ratio of after 1 round trip. In a second, monolithic
cavity, we increase this lifetime to 1.75s (35 round trips) with a memory
efficiency of (SNR of ) after 1 round trip.
Fiber-based cavities for quantum storage at telecom wavelengths offer a
promising route to synchronizing spontaneous photon generation events and
building scalable quantum networks.Comment: 8 pages, 7 figure
Raman gain from waveguides inscribed in KGd(WO₄)₂ by high repetition rate femtosecond laser
We report the formation of waveguides in Raman-active KGd(WO₄)₂ with a focused, high repetition rate femtosecond laser. Parallel guiding regions, formed to either side of the laser-induced damage track, supported TE and TM modes that coupled efficiently to optical fiber at telecom wavelengths. Micro-Raman spectroscopy of the guiding regions revealed the preservation of the characteristic 768 and 901cm¯¹ Raman mode intensities. Raman gain with 6% efficiency was demonstrated for the 768cm¯¹ Raman line by pumping the waveguide with an infrared 80ps source, the first time Raman gain has been reported in laser formed waveguides
Rapid assessment of nonlinear optical propagation effects in dielectrics
Ultrafast laser processing applications need fast approaches to assess the nonlinear propagation of the laser beam in order to predict the optimal range of processing parameters in a wide variety of cases. We develop here a method based on the simple monitoring of the nonlinear beam shaping against numerical prediction. The numerical code solves the nonlinear Schrödinger equation with nonlinear absorption under simplified conditions by employing a state-of-the art computationally efficient approach. By comparing with experimental results we can rapidly estimate the nonlinear refractive index and nonlinear absorption coefficients of the material. The validity of this approach has been tested in a variety of experiments where nonlinearities play a key role, like spatial soliton shaping or fs-laser waveguide writing. The approach provides excellent results for propagated power densities for which free carrier generation effects can be neglected. Above such a threshold, the peculiarities of the nonlinear propagation of elliptical beams enable acquiring an instantaneous picture of the deposition of energy inside the material realistic enough to estimate the effective nonlinear refractive index and nonlinear absorption coefficients that can be used for predicting the spatial distribution of energy deposition inside the material and controlling the beam in the writing process
Three-dimensional opto-fluidic devices fabricated by ultrashort laser pulses for high throughput single cell detection and processing
Particle trapping in 3-D using a single fiber probe with an annular light distribution
NRC publication: Ye
Creation of chiral structures inside fused silica glass
Circularly polarized (CP) femtosecond laser light focused into fused silica produces a permanent recording of optical helicity. Material modification is in the form of highly ordered submicrometer chiral structures whose handedness follows the handedness of the CP light. The evolution of the ordered structures from chaotic modification is described
Applications of femtosecond laser induced self-organized planar nanocracks inside fused silica glass
NRC publication: Ye
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