A Q-switched laser includes a laser cavity including a cavity mirror and an output coupler mirror. The Q-switched laser also includes a doped laser gain material disposed in the laser cavity and a Q-switch including a saturable absorber comprising Fe.sup.2+:ZnSe or Fe.sup.2+:ZnS.

A joined body (10) includes an optical material (11) and a cooling material (12) that are capable of transmitting light and are joined together. At a joining interface between the optical material (11) and the cooling material (12), the joined body (10) is capable of transmitting light, and also an atom contained in the optical material (11) diffusively enters the cooling material (12) in such a degree that an interference fringe is not generated in the joined body (10). A diffusive entry length of an atom contained in the optical material (11) into the cooling material (12) may be in a range from approximately 1.0 nm to approximately 10 m.

The present application discloses a double-clad crystal fiber which includes a Yb-doped CALGO core region, a pump cladding region configured to have the core region positioned therein, and a second cladding region configured to have the core region and pump cladding region positioned therein.

A laser ignition system, in particular for an internal combustion engine, including a vertical emitter and a laser-active crystal, the laser-active crystal being doped in at least some areas using ytterbium, the ytterbium-doped area having a length of 200 m to 7000 m. The monolithic laser is based on a YAG or LuAG host crystal having 3 differently doped areas: a laser-active ytterbium-doped area, an undoped area which determines the resonator length and therefore the pulse duration, and a chromium-doped or vanadium-doped area for the passive Q-switch. The resonator is delimited by 2 mirrors.

A laser device including a resonator including a columnar solid-state laser rod, a first reflective film provided on a first end face of the solid-state laser rod, and a second reflective film provided on a second end face of the solid-state laser rod opposite to the first end face; and a flash lamp configured to excite the solid-state laser rod. The first reflective film and the second reflective film are of an ion beam sputtered coating film capable of preventing moisture from entering from outside air. The first reflective film is lower in reflectance than the second reflective film.