Holographic optical element to generate achromatic vortices

A compound holographic optical element to generate achromatic vortices with high efficiency, based on the combination of two volume phase holograms, is designed and constructed. This element is compact and easy to align. It has high damage threshold, so it can be used with ultraintense laser pulses.This research has been supported by the Spanish Ministerio de Economía y Competitividad (grant FIS2012-35433) and the Diputación General de Aragón (Grupo Consolidado TOL, T76

Holographic Optical Elements to Generate Achromatic Vortices with Ultra-Short and Ultra-Intense Laser Pulses

The requirements for the generation of optical vortices with ultra-short and ultra-intense laser pulses are considered. Several optical vortice generation procedures are analysed, specifically those based on diffractive elements, such as computer generated holograms (CGH). Optical vortices achromatization techniques are studied. Volume phase holographic (VPH) elements are considered for highly efficient, broad spectrum, high damage-threshold generation of vortices. VPH compound systems, including a compact one, for achromatic vortex generation are presented. Experimental results of vortice generation with ultra-short and ultra-intense pulses are shown

Spatiotemporal evolution of light during propagation in filamentation regime

The full description of the evolution of light during its nonlinear propagation represents a valuable help to the complete understanding of important nonlinear phenomena such as light filamentation. In this paper we present a comparison between theoretical and experimental results of the spatiotemporal structure of a light filament at different propagation distances. In order to obtain the experimental spatiotemporal structure, we have used a technique based on spatially resolved spectral interferometry called STARFISH, for spatiotemporal amplitude-and-phase reconstruction by Fourier transform of interference spectra of high-complex beams. We have been able to observe important nonlinear pulse dynamics during the nonlinear propagation, including pulse splitting and the subsequent competition among the pulses that result from the splitting, obtaining a full insight into the general nonlinear behaviorWe acknowledge support from the Spanish Ministerio de Ciencia e Innovación through the Consolider Program Science and Applications of Ultrafast and Ultra-intense Lasers (SAUUL) (CSD2007-00013) and Research Project FIS2009-09522; from Junta de Castilla y León through the Program for Groups of Excellence (GR27) and Research Project SA002B08; and from the European Community’s Seventh Framework Programme (LASERLAB-EUROPE) grant agreement 228334). We also acknowledge support from the Centro de Laseres Pulsados (CLPU), Salamanca, Spain. B. Alonso and I. J. Sola acknowledge the support of the Spanish Ministerio de Ciencia e Innovación through the “Formación de Profesorado Universitario” and “Ramón y Cajal” grant programs, respectively

Tailoring the spatio-temporal distribution of diffractive focused ultrashort pulses through pulse shaping

Focusing control of ultrashort pulsed beams is an important research topic, due to its impact to subsequent interaction with matter. In this work, we study the propagation near the focus of ultrashort laser pulses of ~25 fs duration under diffractive focusing. We perform the spatio-spectral and spatio-temporal measurements of their amplitude and phase, complemented by the corresponding simulations. With them, we demonstrate that pulse shaping allows modifying in a controlled way not only the spatiotemporal distribution of the light irradiance in the focal region, but also the way it propagates as well as the frequency distribution within the pulse (temporal chirp). To gain a further intuitive insight, the role of diverse added spectral phase components is analyzed, showing the symmetries that arise for each case. In particular, we compare the effects, similarities and differences of the second and third order dispersion cases

Intratumoral injection of dendritic cells engineered to secrete interleukin-12 by recombinant adenovirus in patients with metastatic gastrointestinal carcinomas.

PURPOSE: To evaluate the feasibility and safety of intratumoral injection of autologous dendritic cells (DCs) transfected with an adenovirus encoding interleukin-12 genes (AFIL-12) for patients with metastatic gastrointestinal carcinomas. Secondarily, we have evaluated biologic effects and antitumoral activity. PATIENTS AND METHODS: Seventeen patients with metastatic pancreatic (n = 3), colorectal (n = 5), or primary liver (n = 9) malignancies entered the study. DCs were generated from CD14+ monocytes from leukapheresis, cultured and transfected with AFIL-12 before administration. Doses from 10 x 10(6) to 50 x 10(6) cells were escalated in three cohorts of patients. Patients received up to three doses at 21-day intervals. RESULTS: Fifteen (88%) and 11 of 17 (65%) patients were assessable for toxicity and response, respectively. Intratumoral DC injections were mainly guided by ultrasound. Treatment was well tolerated. The most common side effects were lymphopenia, fever, and malaise. Interferon gamma and interleukin-6 serum concentrations were increased in 15 patients after each treatment, as well as peripheral blood natural killer activity in five patients. DC transfected with AFIL-12 stimulated a potent antibody response against adenoviral capsides. DC treatment induced a marked increase of infiltrating CD8+ T lymphocytes in three of 11 tumor biopsies analyzed. A partial response was observed in one patient with pancreatic carcinoma. Stable disease was observed in two patients and progression in eight patients, with two of the cases fast-progressing during treatment. CONCLUSION: Intratumoral injection of DC transfected with an adenovirus encoding interleukin-12 to patients with metastatic gastrointestinal malignancies is feasible and well tolerated. Further studies are necessary to define and increase clinical efficacy

Roadmap on spatiotemporal light fields

Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents the holy grail of the human everlasting pursue of ultrafast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell's equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird's eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges.Comment: This is the version of the article before peer review or editing, as submitted by an author to Journal of Optics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

Ultraestable spatiotemporal characterization of optical vortices in the visible and near infrared

We show the versatility of the bulk lateral shearing interferometer characterizing complex spatiotemporal structures in different spectral ranges. Specifically, we have characterized constant and timevarying optical vortices in the visible and near infrared spectral ranges respectively. The high stability of the system combined with its spectral versatility will ease the spatiotemporal characterization of ultrafast phenomena

Spatiotemporal characterization of few-cycle laser pulses

In this paper we apply a broadband fiber optic coupler interferometer to the measurement of few-cycle laser pulses. Sub-8-fs pulses delivered by an ultrafast oscillator were characterized spatiotemporally using STARFISH, which is based on spatially resolved spectral interferometry. The reference pulse was measured with the d-scan technique. The pulses were focused by an off-axis parabolic mirror and were characterized at different transverse planes along the focusing region. The evolution of the retrieved pulses is analyzed, exhibiting small variations in the temporal (and spectral) amplitude and phase during propagation. Finally, the peak irradiance evolution is estimated from the integration of the spatiotemporal intensity.Spanish Ministerio de Ciencia e Innovación (MICINN) through the Consolider Program SAUUL (CSD2007-00013), Research projects FIS2009-09522, and grant programs Formación de Profesorado Universitario (No. AP2007-00236 for B. Alonso) and Ramón y Cajal (for I. J. Sola); and from the Junta de Castilla y León through the Program for Groups of Excellence (GR27). H. Crespo acknowledges Fundos FEDER, through Programa Operacional Factores de Competitividade – COMPETE, and Fundação para a Ciência e a Tecnologia (FCT) under grants No. PTDC/FIS/115102/2009 and PTDC/FIS/122511/2010. M. Miranda acknowledges FCT and FEDER grant No. SFRH/BD/37100/2007. We also acknowledge support from Centro de Láseres Pulsados (CLPU), Salamanca, Spain

Optical vortex production mediated by azimuthal index of radial polarization

Special light beams are becoming more and more interesting due to their applications in particle manipulation, micromachining, telecommunications or light matter-interaction. Both spin and orbital angular momenta of light are exploited often in combination with spatially varying linear polarization profiles (e.g. radial or azimuthal distributions). In this work we study the interaction between those polarization profiles and the spin-orbit angular momenta, finding the relation involved in the mode coupling. We find that this manipulation can be used for in-line production of collinear optical vortices with different topological charges, which can be filtered or combined with controlled linear polarization. The results are valid for continuous wave and ultrashort pulses, as well as for collimated and focused beams. We theoretically demonstrate the proposal, which is further confirmed with numerical simulations and experimental measurements with ultrashort laser pulses. </p