Rotational Doppler shift from a rotating rod.

This Letter reports on a rotational Doppler effect obtained from a rotating rod illuminated by a fundamental Gaussian laser beam. More specifically, we decompose the transmitted light behind the rotating rod into Laguerre-Gaussian modes and investigate the associated frequency shifts. The main contributing modes correspond to modes having the same rotational symmetry as the rotating object.

Generation of high conical angle Bessel-Gauss beams with reflective axicons.

We report the generation of Bessel-Gauss beams of high conical angle, up to 35 deg, using reflective off-axis axicons and a magnification optical system. We experimentally characterize the beams with three-dimensional scans. The high precision of fabrication of the axicons in the vicinity of the axicon singularity allows us to generate a beam with intensity distribution close to analytical description.

High-Capacity Free-Space Optical Communications Between a Ground Transmitter and a Ground Receiver via a UAV Using Multiplexing of Multiple Orbital-Angular-Momentum Beams.

We explore the use of orbital-angular-momentum (OAM)-multiplexing to increase the capacity of free-space data transmission to moving platforms, with an added potential benefit of decreasing the probability of data intercept. Specifically, we experimentally demonstrate and characterize the performance of an OAM-multiplexed, free-space optical (FSO) communications link between a ground transmitter and a ground receiver via a moving unmanned-aerial-vehicle (UAV). We achieve a total capacity of 80 Gbit/s up to 100-m-roundtrip link by multiplexing 2 OAM beams, each carrying a 40-Gbit/s quadrature-phase-shift-keying (QPSK) signal.

Continuous axial scanning of a Gaussian beam via beam steering.

We propose and demonstrate experimentally the transfer of one spatial degree of freedom of a laser beam onto another one. Using a multi-plane light conversion device (MPLC) and a modal analysis, we designed a passive setup with immediate response which couples a displacement and tilt in the transverse plane to a longitudinal shift of the focus point of a beam. With this design, we demonstrated a shift of the focal point of the output beam by 4 zR along the propagation axis.

4×10 Gbit/s bidirectional transmission over 2 km of conventional graded-index OM1 multimode fiber using mode group division multiplexing.

We demonstrate 4 × 10 Gbit/s error-free bidirectional transmission over 2 km of conventional OM1 graded-index multimode fiber using OOK modulation and direct detection. We also perform field transmission to show reach and capacity boosts on legacy multimode infrastructure. Such transmission is enabled by selective mode group division multiplexing, based on multi-plane light conversion over 4 mode groups of the multimode fiber.

Amplification sharing of non-degenerate modes in an elliptical-core few-mode erbium-doped fiber.

We report on the study of a possible first step integration of mode division multiplexed optical component for single-mode fiber networks. State-of-the-art on few-mode erbium-doped fiber amplifiers is used to integrate the amplification function in a single component, which is expected to save energy in comparison to parallelized active components. So as to limit the impact of modal cross-talk, an elliptical-core few-mode erbium-doped fiber has been used to assemble an amplifier sharing setup for different single mode fibers, using non-degenerate modes.

Efficient and mode selective spatial mode multiplexer based on multi-plane light conversion.

We designed and built a new type of spatial mode multiplexer, based on Multi-Plane Light Conversion (MPLC), with very low intrinsic loss and high mode selectivity. In this first demonstration we show that a typical 3-mode multiplexer achieves a mode selectivity better than -23 dB and a total insertion efficiency of -4.1 dB (optical coating improvements could increase efficiency to -2.

Pulse shaping with birefringent crystals: a tool for quantum metrology.

A method for time differentiation based on a Babinet-Soleil-Bravais compensator is introduced. The complex transfer function of the device is measured using polarization spectral interferometry. Time differentiation of both the pulse field and pulse envelope are demonstrated over a spectral width of about 100 THz with a measured overlap with the objective mode greater than 99.

Multicolor two-photon tissue imaging by wavelength mixing.

We achieve simultaneous two-photon excitation of three chromophores with distinct absorption spectra using synchronized pulses from a femtosecond laser and an optical parametric oscillator. The two beams generate separate multiphoton processes, and their spatiotemporal overlap provides an additional two-photon excitation route, with submicrometer overlay of the color channels. We report volume and live multicolor imaging of 'Brainbow'-labeled tissues as well as simultaneous three-color fluorescence and third-harmonic imaging of fly embryos.

Combined third-harmonic generation and four-wave mixing microscopy of tissues and embryos.

Nonlinear microscopy can be used to probe the intrinsic optical properties of biological tissues. Using femtosecond pulses, third-harmonic generation (THG) and four-wave mixing (FWM) signals can be efficiently produced and detected simultaneously. Both signals probe a similar parameter, i.

Dispersion-based pulse shaping for multiplexed two-photon fluorescence microscopy.

We demonstrate selective two-photon excited fluorescence microscopy with shaped pulses produced with a simple yet efficient scheme based on dispersive optical components. The pulse train from a broadband oscillator is split into two subtrains that are sent through different amounts of glass. Beam recombination results in pulse-shape switching at a rate of 150MHz.

Multiplexed two-photon microscopy of dynamic biological samples with shaped broadband pulses.

Coherent control can be used to selectively enhance or cancel concurrent multiphoton processes, and has been suggested as a means to achieve nonlinear microscopy of multiple signals. Here we report multiplexed two-photon imaging in vivo with fast pixel rates and micrometer resolution. We control broadband laser pulses with a shaping scheme combining diffraction on an optically-addressed spatial light modulator and a scanning mirror allowing to switch between programmable shapes at kiloHertz rates.

Bcr-abl translocation can occur during the induction of multidrug resistance and confers apoptosis resistance on myeloid leukemic cell lines.

Apoptosis was studied in parental and mdr-1 expressing U937, HL60 and K562 myeloid leukemic cell lines using mdr unrelated inducers of apoptosis such as Ara-C, cycloheximide, serum deprivation, ceramide, monensin and UV irradiation. Apoptosis was efficiently induced by all these treatments in U937 and HL60 cells while K562 cells exhibited an apoptosis-resistant phenotype except with UV and monensin. The pattern of apoptosis resistance in mdr-1 expressing U937 (U937-DR) and HL60 (HL60-DR100) was similar to that presented by K562.

Study of apoptosis-related responses of leukemic blast cells to in vitro anthracycline treatment.

Anthracyclines trigger an apoptotic cell death but their molecular targets are not totally explored. We investigated the apoptotic response of blast cells and lymphocytes from medullary samples of 31 de novo acute leukemia. Mononuclear cells were treated in vitro by therapeutic concentrations of either daunorubicin (DNR) or idarubicin (IDA) for 1 h, washed and cultured for 18 h.

Flow cytometric evaluation of fas expression in relation to response and resistance to anthracyclines in leukemic cells.

Background: Cell chemosensitivity to cytotoxic drugs has been attributed to their ability to trigger apoptosis. The emergence of resistance in drug-exposed cells is often characterized by the appearance of drug efflux mechanisms including P-gp transport. Nevertheless, mdr1 expression may coexist with other resistance features, in particular those interfering with apoptotic signaling pathways.

Cytometric study of intracellular P-gp expression and reversal of drug resistance.

Expression of the multidrug resistance (MDR) phenotype is responsible for chemotherapy failure in numerous cancers. This phenotype is generally due to the expression of the mdr1 gene-encoded P-gp. Modulation of P-gp activity by chemotherapy has limited possibilities because of toxicity and poor specificity.

Evaluation of the leukocyte differential flags on an hematologic analyzer. The Cobas Argos 5 Diff.

To evaluate the leukocyte differential flags of the Cobas Argos 5 Diff., the authors performed a comparative study between their current analyzer, the Technicon H2, and the manual leukocyte differential. Samples (n = 1,600) were collected from the Blood Disease Department of their hospital and were tested on both Cobas Argos 5 Diff.