An optical resonator for a medical laser system is provided. The optical resonator comprises a lasing medium, an optical pump, and a high-reflective (HR) and an optical coupling (OC) reflector. The HR and OC reflectors are disposed symmetrically relative to the lasing medium and the HR mirror, the OC mirror, or both the HR mirror and the OC mirror are flat mirrors. The optical resonator also includes a doped insert in which the lasing medium is disposed.

A visible laser or laser amplifier is provided with a ceramic gain medium having a uniaxial anisotropic scattering property such that scattering losses for a visible laser beam along one axis are lower than that along perpendicular axes, and that axis is used as the optical path. The ceramic gain medium includes at least a trivalent praseodymium dopant (Pr.sup.3+) within a host body based on CaF.sub.2, SrF.sub.2, BaF.sub.2, or a solid solution thereof. Co-dopants can include one or more other trivalent rare earth (RE) elements chosen from Lu.sup.3+, Y.sup.3+, Gd.sup.3+, and La.sup.3+. The ceramic gain medium, which is made from wet-chemistry precipitated powders, undergoes uniaxial compression, generally under high heat, as an essential step in its manufacture. In use, a pump source using a laser diode of gallium nitride-based semiconductor can be advantageously paired with the gain medium.

A medical laser system for outputting laser pulses includes at least one laser cavity configured to generate at least one laser pulse, a rotating mirror configured to receive and reflect the at least one laser pulse, a beam splitter configured to receive and reflect a portion of the at least one laser pulse received from the rotating mirror, an energy-sensing device configured to detect the portion of the at least one laser pulse, an energy measurement assembly configured to generate a feedback signal based on the portion of the at least one laser pulse detected by the energy-sensing device, and a controller configured to generate an electronic control pulse based on the feedback signal received from the energy measurement assembly to generate at least one adjusted laser pulse.

High output power and stable operation are achieved in a semiconductor laser pumped solid state laser. An LD pumped solid state laser 90 includes a solid state laser crystal 19 such as a Pr:YLF crystal, a plurality of LDs 11 that emits a pumping light beam L to pump the laser crystal 19, a resonator that resonates the light emitted from the solid state laser crystal 19, and a wavelength control means such as a narrow bandpass filter 13 to cause an emission wavelength of the pumping light beam L by the LD 11 to match an absorption peak wavelength of the solid state laser crystal 19.

An optical fiber and an optical amplifier including the optical fiber are disclosed, the optical fiber includes a core region for guiding a propagation of a multimode optical signal, a cladding region laterally surrounding the core region and at least two doped rings, each of the at least two doped rings having a corresponding rare-earth or transition metal dopant concentration. The core region includes a central core having a first refractive index, at least one core layer laterally surrounding the central core, each of the at least one core layer having corresponding internal and external radii, an internal radius of an innermost core layer corresponding to a radius of the central core and an external radius of the outermost core layer corresponding to a radius of the core region.