Spatial chirp and angular dispersion of the nonlinear crystal for a femtosecond OPO

We present the design and experiment of a broadband optical parametric chirped-pulse amplifier (OPCPA) which provides high conversion efficiency and good beam quality at 808 nm wavelength. Using a three-dimensional spatial and temporal numerical model, several design considerations necessary to achieve high conversion efficiency, good beam quality and good output stability are discussed. To improve the conversion efficiency and broaden the amplified signal bandwidth simultaneously, the nonlinear crystal length and OPCPA parameters are analyzed and optimized with the concept of dissipating amplified idler between optical parametric amplification (OPA) of two crystals configuration. In the experiment, an amplifier consisting of two OPCPA stages of ‘L’ type configuration was demonstrated by using the optimized parameters. An amplified signal energy of 160 mJ was achieved with a total pump-to-signal efficiency of 35% (43% efficiency for the OPCPA stage 2). The output bandwidth of signal pulse reached 80 nm and the signal pulse was compressed to 24 fs. The energy stability reached 1.67% RMS at 3% pump energy variation. The optimized OPCPA amplifier operates at a repetition rate of 1 Hz and is used as a front-end injection for the main amplifier of SG-II 5PW laser facility.

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Quantitative estimates of average geomagnetic axial dipole dominance in deep geological time

Nature Communications ◽

10.1038/s41467-020-19794-7 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Andrew J. Biggin ◽

Richard K. Bono ◽

Domenico G. Meduri ◽

Courtney J. Sprain ◽

Christopher J. Davies ◽

...

Keyword(s):

Power Law ◽

Geomagnetic Field ◽

Recent Observation ◽

Observational Constraint ◽

Angular Dispersion ◽

Geological Time ◽

Future Studies ◽

Axial Dipole ◽

Quantitative Estimates

AbstractA defining characteristic of the recent geomagnetic field is its dominant axial dipole which provides its navigational utility and dictates the shape of the magnetosphere. Going back through time, much less is known about the degree of axial dipole dominance. Here we use a substantial and diverse set of 3D numerical dynamo simulations and recent observation-based field models to derive a power law relationship between the angular dispersion of virtual geomagnetic poles at the equator and the median axial dipole dominance measured at Earth’s surface. Applying this relation to published estimates of equatorial angular dispersion implies that geomagnetic axial dipole dominance averaged over 107–109 years has remained moderately high and stable through large parts of geological time. This provides an observational constraint to future studies of the geodynamo and palaeomagnetosphere. It also provides some reassurance as to the reliability of palaeogeographical reconstructions provided by palaeomagnetism.

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Angular dispersion compensation for acousto-optic devices used for ultrashort-pulsed laser micromachining

Optics Express ◽

10.1364/oe.9.000200 ◽

2001 ◽

Vol 9 (4) ◽

pp. 200 ◽

Cited By ~ 27

Author(s):

B.K. Ann Ngoi ◽

Krishnan Venkatakrishnan ◽

L.E.N. Lim ◽

B. Tan

Keyword(s):

Dispersion Compensation ◽

Pulsed Laser ◽

Laser Micromachining ◽

Angular Dispersion ◽

Ultrashort Pulsed Laser

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Blue 473-nm solid state diode pumped Nd:YAG/BiBO microchip laser

Opto-Electronics Review ◽

10.2478/s11772-009-0018-7 ◽

2010 ◽

Vol 18 (1) ◽

Author(s):

A. Antończak ◽

J. Sotor ◽

M. Matysiak ◽

K. Abramski

Keyword(s):

Blue Light ◽

Second Harmonic ◽

Nonlinear Crystal ◽

Phase Matching ◽

Type I ◽

Pumping Power ◽

Diode Pumped ◽

Light Generation ◽

Power Diode ◽

Matching Type

AbstractIn this paper we present a design of a compact, low power diode-pumped CW Nd:YAG laser operating at 946 nm with intracavity blue light generation at 473 nm for battery operated applications. The nonlinear crystal used in the experiment is a BiBO crystal cut for phase-matching type I. Using 0.8 W of pumping power, 20-mW stabile output power of blue light was achieved. The second harmonic generation conversion efficiency was 2.5%.

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