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.

In a Q-switched solid-state laser having a resonator (3, 30) in the form of a linear resonator or a ring resonator having an active laser material (1) and at least one first and one second mirror (4, 5) and a resonator length (a) of less than 50 mm, preferably less than 25 mm, in the case of the configuration as a linear resonator and of less than 100 mm, preferably less than 50 mm, in the case of the configuration as a ring resonator, at least substantially only one longitudinal mode oscillates in the resonator (3). The resonator (3, 30) is in the form of an unstable resonator, with one of the mirrors (4, 5) being a gradient mirror.

Fiber laser having a monolithic laser resonator having laser affected zones for providing laser beams having wavelengths below 800 nm and from between 400 nm to 800 nm. Methods of using femtosecond lasers to form fiber Bragg gratings, volume Bragg gratings, space gratings, and laser beam delivery patterns for changing the index of refraction within optical fibers.

In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

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.

A laser source includes an optical resonator including first and second reflectors having first and second reflection spectral bands. A gain medium is disposed in the optical resonator. The gain medium has a gain spectrum. Center wavelengths of at least two of: the first reflection spectral band; the second reflection spectral band; or the gain spectrum are offset relative to each other for reduction of a spectral variance of the laser source. For example, the first and the second reflection spectral bands may be offset relative to one another to form an overlap area above a lasing threshold. The lasing is limited to the overlap area. When the overlap area accommodates a single lasing mode, the output emission of the laser source is monochromatic.

An apparatus and source arrangement for filtering an electromagnetic radiation can be provided which may include at least one spectral separating arrangement configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus and source arrangement may also have at least one continuously rotating optical arrangement which is configured to receive at least one signal that is associated with the one or more components. Further, the apparatus and source arrangement can include at least one beam selecting arrangement configured to receive the signal.

A laser system includes a first laser source with a laser resonator for generating a first pulsed laser beam. The resonator has a back mirror, an outcoupling mirror and an active lasing medium in between. The system includes a second laser source for generating a second pulsed laser beam and an optical block. The optical block includes a coupling polarizer and a first polarization rotator. The optical block is movable back and forth between an active position and a passive position. In its active position the optical block is located between the outcoupling mirror and the active lasing medium such that the coupling polarizer couples the second beam into the laser resonator of the first laser source while the first rotator is positioned between the outcoupling mirror and the coupling polarizer. In the active position of the optical block a second polarization rotator is between it and the back mirror.

In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

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.