1,720,962 research outputs found
Performance of a continuous-wave self-adaptive gain-grating laser
No full textExperimental and theoretical studies have shown that three-dimensional gain gratings, optically written in a saturable laser amplifier, can act as very efficient (>1000%) diffractive optical elements and, in a four-wave mixing (FWM) geometry, can produce extremely high phase-conjugate reflectivity. A further development in the use of gain gratings for phase conjugation has been the employment of loop schemes to obtain self-pumped phase conjugation (SPPC) with only one input beam required. In reality, these devices are actually a novel type of (holographic) laser where the feedback is provided by diffraction from an externally-written gain-grating hologram
Continuous wave holographic laser resonators using degenerate four-wave mixing in a diode bar side-pumped Nd:YVO<sub>4</sub> amplifier
No full textDegenerate four-wave mixing techniques used to produce self-adaptive laser resonators based on diffraction from a gain grating have shown considerable promise for correction of distortion in high-average-power solid-state laser systems, as well as for spectral and temporal control of the laser radiation [1-4]. In these systems, the gain grating is formed by spatial hole burning caused by interference of coherent beams in the laser amplifier and modulation of the population inversion. The gain grating formation can be used for phase conjugation by using the amplifier in a four-wave mixing geometry [2], for self-pumped phase conjugation by using an input beam in a self-intersecting loop geometry [3] and for formation of a self-starting adaptive oscillator by providing additional feedback from an output coupler and requiring no external optical input. Experimental demonstrations have been performed successfully in several laser systems including flashlamp-pumped and quasi-c.w. pumped neodymium-doped amplifiers [1,2], in laser-pumped titanium-doped sapphire [4] and CO2 lasers. We present for the first time, demonstration of a continuous-wave self-adaptive holographic laser resonator. The operation is based on the very high reflectivities (>800%) [5] and more recently (>10,000%) of a gain grating formed in a diode-bar side-pumped Nd:YVO4 amplifier. We have subsequently modelled the FWM interactions and have found good agreement with experimental results. This resonator has been shown to correct for severe phase distortions introduced inside the loop. An output of ~1 W has so far been achieved, future steps include an additional power amplifier incorporated into the resonator loop geometry to give an expected multi-watt operation with a midterm goal of 10 W
Continuous wave adaptive laser resonators using degenerate four-wave mixing in a diode bar side-pumped Nd:YVO<sub>4</sub> amplifier
No full textSelf-adaptive laser resonators based on diffraction from a gain grating have shown considerable promise for correction of distortion in high-average-power solid-state laser systems, as well as for spectral and temporal control of the laser radiation [1-4]. In these systems, the gain grating is formed by spatial hole burning caused by interference of coherent beams in the laser amplifier and modulation of the population inversion. The gain grating formation can be used for phase conjugation by using the amplifier in a four-wave mixing geometry [2], for self-pumped phase conjugation by using an input beam in a self-intersecting loop geometry [3] and for formation of a self-starting adaptive oscillator by providing additional feedback from an output coupler and requiring no external optical input. Experimental demonstrations have been performed successfully in several laser systems including flashlamp-pumped and quasi-c.w. pumped neodymium-doped amplifiers [1,2], in laser-pumped titanium-doped sapphire [4] and CO2 lasers. We present for the first time, demonstration of a continuous-wave self-adaptive holographic laser resonator. The operation is based on the very high reflectivities (>100) of a gain grating formed in a diode-bar side-pumped Nd:YVO4 amplifier
Multi-watt continuous-wave adaptive laser resonator
No full textWe present, for what we believe is the first time, results of continuous-wave diode-pumping of a Nd:YVO4 laser with an adaptive gain-grating resonator. The system is shown to produce more than a 7W output in a TEM00 single longitudinal mode with a laser beam propagation parameter M2 of 1.3 and 1.1 in the x and y axes, respectively. We demonstrate the self-adaptive abilities of the resonator by spatial correction of an intracavity aberrator for both injected and self-starting versions of the cavity
High-reflectivity continuous-wave phase conjugation by four-wave mixing in a diode-pumped Nd:YVO<sub>4</sub> amplifier
No full textWe present the first demonstration of continuous-wave diode-pumped four-wave mixing in a Nd:YVO4 amplifier and achieve phase conjugate reflectivity > 800%. Results for different amplifier gains and pump geometries are compared to numerical results
Holographic laser resonators using degenerate four-wave mixing in a continuous wave side-pumped Nd:YVO<sub>4</sub> amplifier
No full textDegenerate four-wave mixing results are presented for continuous wave diode pumped Nd:YVO4, yielding >800% reflectivity, and an adaptive phase conjugate resonator has thereby been constructed
High phase conjugate reflectivity (>800%) by degenerate four-wave mixing in a continuous wave diode side-pumped Nd:YVO<sub>4</sub> amplifier
No full textHigh-phase-conjugate reflectivities of >800% have been achieved through degenerate four-wave mixing in a cw diode-side-pumped Nd:YVO4 amplifier. Reflectivity curves are shown as a function of input pump-beam intensity for three values of small-signal amplifier gain, and comparison is made with a numerical simulation
Distortion correcting holographic resonators
No full textHigh phase conjugate reflectivities (R > 10,000%) have been achieved through degenerate four-wave mixing in a cw diode-side-pumped Nd:YVO4 amplifier and the interactions have been successfully modelled. This four-wave mixing geometry has subsequently been used in the design of a phase-conjugate resonator operating with a single-longitudinal mode TEMoo near-diffraction limited output of >7W, which is capable of correcting for severe intra-cavity phase distortions. <br/
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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