A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness t supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

Efficient laser diode excited Thulium (Tm) doped solid state systems, directly matched to a combination band pump transition of Carbon Dioxide (CO.sub.2), have matured to the point that utilization of such in combination with CO.sub.2 admits effectively a laser diode pumped CO.sub.2 laser. The laser diode excited Tm solid state pump permits Continuous Wave (CW) or pulsed energy application. Appropriate optical pumping admits catalyzer free near indefinite gas lifetime courtesy of the absence of significant discharge driven dissociation and contamination. As a direct consequence of the preceding arbitrary multi isotopologue CO.sub.2, symmetric and asymmetric, gas mixes may be utilized without significant degradation or departure from initial mix specifications. This would admit, at raised pressure, a system continuously tunable from approximately 9 m to approximately 11.5 m, or sub picosecond amplification. This method offers advantages in regards scalability, pulse energy and power, over alternative non linear conversion techniques in access to this spectral region.

Efficient laser diode excited Thulium (Tm) doped solid state systems, directly matched to a combination band pump transition of Carbon Dioxide (CO.sub.2), have matured to the point that utilization of such in combination with CO.sub.2 admits effectively a laser diode pumped CO.sub.2 laser. The laser diode excited Tm solid state pump permits Continuous Wave (CW) or pulsed energy application. Appropriate optical pumping admits catalyzer free near indefinite gas lifetime courtesy of the absence of significant discharge driven dissociation and contamination. As a direct consequence of the preceding arbitrary multi isotopologue CO.sub.2, symmetric and asymmetric, gas mixes may be utilized without significant degradation or departure from initial mix specifications. This would admit, at raised pressure, a system continuously tunable from approximately 9 m to approximately 11.5 m, or sub picosecond amplification. This method offers advantages in regards scalability, pulse energy and power, over alternative non linear conversion techniques in access to this spectral region.

Methods, devices, and apparatus for generating plasma or laser pulses by radio frequency (RF) excitation pulses are provided. In one aspect, a method includes specifying radio frequency (RF) excitation pulses at least partially as a function of a preceding RF excitation of a medium and outputting a signal to a RF pulse generator, the signal configured to cause the RF pulse generator to generate the specified RF excitation pulses for exciting the medium to generate plasma or laser pulses. The RF excitation pulses is specified to become more strongly reduced in energy when a remaining excitation of the medium by the preceding RF excitation is higher.

A polarisation and mode selection technique for a gas waveguide laser is described in which a surface of the waveguide is formed to be substantially dielectric with a localised metallic region therein. The metallic region provides linear polarisation while the dielectric surface provides for low order mode selection. Embodiments are described to channel and planar waveguides with various resonator configurations. Ranges are provided for the size and location of the metallic region on the waveguide surface.

Disclosed are methods, devices and systems to cause differential evaporation of micro-droplets in a scalable fashion. In some embodiments, an attenuated laser is used to focus an attenuated laser power to the center of an aqueous solution droplet, producing a differential evaporative flux profile that is peaked at the droplet apex. The laser-induced differential evaporation described herein is a breakthrough in the enrichment and focused deposition of water-soluble molecules such as nucleic acids, proteins, inks, and other small molecules. Disclosed is a general solution to remove the coffee-ring effect, ubiquitous in the drying process of aqueous droplets that causes many adverse outcomes. The disclosed techniques enable new paradigms in liquid biopsy combinational analysis, microarray fabrication, and ink-jet printing.

A carbon dioxide gas-discharge slab-laser is assembled in a laser-housing. The laser-housing is formed from a hollow extrusion. An interior surface of the extrusion provides a ground electrode of the laser. Another live electrode is located within the extrusion, electrically insulated from and parallel to the ground electrode, forming a discharge-gap of the slab-laser. The electrodes are spaced apart by parallel ceramic strips. Neither the extrusion, nor the live electrode, include fluid coolant channels. The laser-housing is cooled by fluid-cooled plates attached to the outside thereof.

An external optical feedback element (108) for tuning an output beam of a gas laser (102) having multiple wavelengths includes a partially reflective optical element (108) positioned on a beam path of the output beam (106) outside of an internal optical cavity of the gas laser (102), and a stage (114) to support the optical element and adjust rotation, horizontal tilt angle, and vertical tilt angle of the optical element with respect to the beam path. The output beam (106) is partially reflected at the optical element (108) and fed back into the internal optical cavity of the gas laser (102), with the intensity varying for multiple wavelengths and adjusted by changing rotation, horizontal tilt angle and vertical tilt angle of the optical element. Thereby, a variable feedback of the output beam into the internal optical cavity of the gas laser is provided, which leads to a selective output wavelength of the gas laser, either at a single line or at multiple lines simultaneously. This setup may allow to control the wavelength of a commercial CO2 gas laser without a modification of the laser itself by adding a coupled cavity with a wavelength selective element like a grating to the given gas laser resonator.

A positive high-voltage laser having a super-long discharge tube, including a gas storage tube having two ends respectively provided with a reflecting mirror and a light emitting surface; a water cooling tube in the gas storage tube; and a discharge tube inside the water cooling tube having two ends, each provided with an electrode. A liquid circulation space is between the discharge tube and the water cooling tube, and the water cooling tube extends outside the gas storage tube by water inlet and outlet tubes. A cathode is in a cathode chamber at the end of the discharge tube closest to the light emitting surface; a spiral gas return tube communicates with the cathode chamber; an anode circumscribes the outside of the water cooling tube at the other end of the discharge tube. The positive high-voltage laser can increase power with a limited length.

A carbon dioxide gas-discharge slab-laser is assembled in a laser-housing. The laser-housing is formed from a hollow extrusion. An interior surface of the extrusion provides a ground electrode of the laser. Another live electrode is located within the extrusion, electrically insulated from and parallel to the ground electrode, forming a discharge-gap of the slab-laser. The electrodes are spaced apart by parallel ceramic strips. Neither the extrusion, nor the live electrode, include any direct fluid-cooling means. The laser-housing is cooled by fluid-cooled plates attached to the outside thereof.