Continuous-wave 457 blue laser emission at powers as high as 4.6 W is achieved by using a fiber-coupled laser diode array with a power of 30 W to pump 0.1 at.% low-doped bulk Nd:YVO4 crystal, with intracavity frequency doubling in a 15 mm long type I critical phase-matched LiB3O5 (LBO) crystal in a compact threefold cavity with a length of less than 100 mm. The optical-optical conversion efficiency is greater than 15.3%, and the stability of the output power is better than 3% for an hour.

High-power efficient diode-pumped Nd:YVO4/LiB3O5 457 nm blue laser with 4.6 W of output power.

We present results of an investigation to scale a diode-pumped A Nd:GdVO/sub 4/ laser system to high powers (>100 W) using a bounce amplifier configuration. A Nd:GdVO/sub 4/ laser oscillator with a bounce amplifier geometry, pumped by a single 40-W diode bar, gave 24 W of multimode output power (60% optical efficiency), and 20 W of TEM/sub 00/ output with M/sup 2/<1.05. Power scaling of the oscillator system with pumping by multiplexing two (nominally) 40-W diode bars gave 50.1 W of multimode output at 83-W diode pumping, 40 W of predominantly TEM/sub 00/ output from 81-W of diode pumping, and 34 W TEM/sub 00/ output (M/sup 2//sub x/=1.05,M/sup 2//sub y/=1.1) with an external slit spatial filter. Higher power scaling is achieved by using a master-oscillator power-amplifier (MOPA) configuration with the double-diode-pumped oscillator and a bounce amplifier pumped by a 3-bar diode stack. A multimode MOPA output of 100 W is achieved by single pass amplification with 145-W amplifier diode pumping and 104-W TEM/sub 00/ mode using a double bounce amplifier configuration with 180-W amplifier diode pumping.

High-power scaling (>100 W) of a diode-pumped TEM/sub 00/ Nd:GdVO/sub 4/ laser system

Astigmatism is left uncorrected in traditional Czerny-Turner spectrometers with spherical mirrors, which leads to low throughput of modern instruments applying line-array detectors. By gradually varying the sagittal curvature, freeform mirrors are introduced to suppress astigmatism for a wide wavelength range simultaneously. So as not to reduce spectrum resolution, further calculations of the light path are performed for extra coma compensation. A design example is presented with optimized parameters. The ray-tracing result has revealed a reduction in sagittal spot size from several hundred micrometers to around 10 microm in the wavelength range from 200 nm to 800 nm.

Design of freeform mirrors in Czerny-Turner spectrometers to suppress astigmatism

By using a plano-concave cavity, a compact and efficient diode-end-pumped acousto-optic (AO) Q-switched intracavity frequency-doubled Nd:GdVO4/LBO red laser was demonstrated. Under the incident pump power of 9.2 W, the maximum output power at 671 nm was obtained to be 1.36 W at repetition frequency of 15 kHz, with the corresponding optical-optical conversion efficiency of 14.8%. And the shortest pulse width at 671 nm was obtained to be 28 ns at the repetition frequency of 5 kHz. The dependence of the operational parameters on the pump power was also investigated experimentally.

Efficient and compact diode-pumped Q-switched Nd:GdVO4/LBO red laser

The development of mid-infrared, high-energy pulses of extremely short pulse duration is of great importance to the strong-field physics community, as it enables extension of the high-harmonic cutoff towards the keV range of photon energies. Here we demonstrate a Cr2+:ZnSe laser amplifier delivering 7 mJ, 100 fs pulses at 1 kHz repetition rate and 2.4 µm central wavelength with excellent energy stability and beam quality. These pulses are post-compressed to 39 fs, 6.2 mJ, and 115 GW peak power in a novel nonlinear compression scheme. The laser system was used to generate coherent soft x-ray radiation up to 0.6 keV covering the entire water window, which is of high importance for bio-relevant applications. The obtained results open a wide range of applications in nonlinear optics, attosecond and strong-field physics, and remote sensing.

High-power few-cycle Cr:ZnSe mid-infrared source for attosecond soft x-ray physics

A straightforward method is presented for generating a stigmatic spherical thermal lens in laser-diode-pumped, Brewster-cut solid-state gain media by shaping the aspect ratio of the elliptical pumped region. Demonstration of this laser head design with Nd:GdVO(4) as the gain medium yields a stable, efficient, high-power (>20W) diode-pumped laser at 1063nm. Analysis of the spatial mode characteristics of a 67cm-long symmetric resonator both confirms the radially symmetric nature of the pump-induced thermal lens and indicates that laser resonators incorporating this head design can readily generate a high spatial beam quality (M(2) < 2).

Thermal lens shaping in Brewster gain media: A high-power, diode-pumped Nd:GdVO 4 laser

Use of a transverse KD*P Pockels cell and novel low-loss sapphire
Rochon polarizer to cavity dump a hard-aperture, Kerr-lens mode-locked,
Ti:sapphire oscillator is demonstrated. High-quality 90-fs pulses
with energies of ∼50 nJ at repetition rates of up to 50 kHz were
obtained.

Femtosecond Ti:Sapphire Oscillator Electro-Optically Cavity Dumped at 50 kHz.

A high-resolution, flat-field, plane-grating,
f/10 spectrometer based on the novel design proposed by Gil and Simon [Appl. Opt. 22, 152 (1983)] is demonstrated. The spectrometer design employs off-axis parabolic collimation and camera mirrors in a configuration that eliminates spherical aberrations and minimizes astigmatism, coma, and field curvature in the image plane.
In accordance with theoretical analysis, the performance of this spectrometer achieves a high spatial resolution over the large detection area, which is shown to be limited only by the quality of its optics and their proper alignment within the spatial resolution of a
13 μm×13 μm pixelated CCD detector. With a
1500 lines/mm grating in first order, the measured spectral resolving power of
λ/Δλ=2.5(+/-0.5)×104 allows the clear resolution of the violet
Ar(I) doublet at 419.07 and
419.10 nm.

Nathan W. Rimington

Papers

Thermal lens shaping in Brewster gain media: A high-power, diode-pumped Nd:GdVO 4 laser

Femtosecond Ti:Sapphire Oscillator Electro-Optically Cavity Dumped at 50 kHz.

High-resolution, flat-field, plane-grating, f/10 spectrograph with off-axis parabolic mirrors.