An optical plural-comb generator comprising a plurality of mode-locked lasers that are mechanically coupled and optically independent. The optical plural-comb generator comprises an optical combiner optically coupled to an output of each of the plurality of mode-locked lasers for combining a plurality of optical combs when generated by the plurality of mode-locked lasers.

A rare earth-doped optical fiber comprises a fluorosilicate core surrounded by a silica cladding, where the fluorosilicate core comprises an alkaline-earth fluoro-alumino-silicate glass, such as a strontium fluoro-alumino-silicate glass. The rare earth-doped optical fiber may be useful as a high-power fiber laser and/or fiber amplifier. A method of making a rare earth-doped optical fiber comprises: inserting a powder mixture comprising YbF.sub.3, SrF.sub.2, and Al.sub.2O.sub.3 into a silica tube; after inserting the powder mixture, heating the silica tube to a temperature of at least about 2000 C., some or all of the powder mixture undergoing melting; drawing the silica tube to obtain a reduced-diameter fiber; and cooling the reduced-diameter fiber. Thus, a rare earth-doped optical fiber comprising a fluorosilicate core surrounded by a silica cladding is formed.

A voltage-controllable output coupler for a laser, comprising: a liquid crystal cell that provides a change in birefringence in response to an applied voltage; and a polariser oriented with respect to the liquid crystal cell to collectively form a variable reflectance mirror for the laser; wherein output coupling of the laser is controllable by applying voltage to the liquid crystal cell for a switching interval to switch the variable reflectance mirror from high reflectance to low reflectance, and vice versa, thus actively Q-switching or cavity dumping the laser.

A monolithic laser cavity (100, 200, 300, 400) for generating an output series of pulses (37) based on an input pump signal 36. This is achieved by a novel cavity design that utilizes a transparent, low-loss, and near zero-dispersion spacer (38) to form an optical resonator without the use of wave-guiding effects. The pulse forming material (32), optical elements (10-16, 30, 31, 33), and the laser gain medium (34) are in direct contact with the spacer and/or each other without any free-space sections between them. Therefore, the light inside the laser cavity never travels through free space.

A two-dimensional semiconductor saturable absorber mirror comprises an optical fiber, a two-dimensional semiconductor thin film attached to an end surface of the optical fiber, and a gold film attached to the two-dimensional semiconductor thin film. A method for fabricating the two-dimensional semiconductor saturable absorber mirror comprises the following steps: cutting the optical fiber, putting the cut optical fiber and a two-dimensional semiconductor target into a vacuum chamber, ionizing a surface of two-dimensional semiconductor target to generate two-dimensional semiconductor plasma, depositing the two-dimensional semiconductor plasma on an exposed end surface of the optical fiber to form the two-dimensional semiconductor thin film, and by controlling deposition time and/or deposition temperature, ensuring the two-dimensional semiconductor thin film to be a desired thickness; and plating the gold film on the resulting two-dimensional semi-conductor thin film.

The mid-infrared laser system has an amplifier including at least one pump laser adapted to generate a pump laser beam and a length of fiber made of a low phonon energy glass and having at least one laser-active doped region between a first end and a second end, and a seed laser to generate a seed laser beam having a seed optical spectrum in the mid-infrared. The seed laser beam is launched into the first end to generate a mid-infrared laser beam outputted from the second end via stimulated emission upon pumping of the at least one laser-active doped region with the pump laser beam. When the power of the pump laser exceeds a spectrum modification threshold, the mid-infrared laser beam has an output optical spectrum being broadened relative to the seed optical spectrum.

The mid-infrared laser system has an amplifier including at least one pump laser adapted to generate a pump laser beam and a length of fiber made of a low phonon energy glass and having at least one laser-active doped region between a first end and a second end, and a seed laser to generate a seed laser beam having a seed optical spectrum in the mid-infrared. The seed laser beam is launched into the first end to generate a mid-infrared laser beam outputted from the second end via stimulated emission upon pumping of the at least one laser-active doped region with the pump laser beam. When the power of the pump laser exceeds a spectrum modification threshold, the mid-infrared laser beam has an output optical spectrum being broadened relative to the seed optical spectrum.

In an optical fiber device having a configuration in which an optical fiber is joined to a side surface of another optical fiber, a joint portion is suppressed from reaching a high temperature. The optical fiber device includes a first fluoride fiber, a second fluoride fiber, and a heat dissipation member. The first fluoride fiber guides light. The second fluoride fiber has a first end on or from which light is incident or output and a second end at which an end surface of the second fluoride fiber is obliquely joined to a side surface of the first fluoride fiber.

A broadband emission material according to the present invention includes: a fluoride glass containing 20 to 45 mol % of AlF.sub.3, 25 to 63 mol % of alkaline-earth fluorides in total and 3 to 25 mol % of at least one fluoride of element selected from the group consisting of Y, La, Gd and Lu; and ytterbium ions incorporated in the fluoride glass as divalent rare-earth ions so as to serve as a luminescent center, wherein the fluoride glass includes 1 to 15 mol % of at least one halide of element selected from the group consisting of Al, Ba, Sr, Ca and Mg and element selected from the group consisting of Cl, Br and I; and wherein the alkaline-earth fluorides includes 0 to 15 mol % of MgF.sub.2, 7 to 25 mol % of CaF.sub.2, 0 to 22 mol % of SrF.sub.2 and 0 to 5 mol % of BaF.sub.2.

Mid-infrared-transparent optical fiber products with enhanced resistance to OH diffusion are disclosed, which may be used fiber laser oscillator and amplifiers systems. In one embodiment, an optical fiber product may include optical fiber configured for propagation of mid-infrared radiation toward a light-radiating endface of or coupled to the optical fiber, and a diffusion barrier disposed on the light-radiating endface and configured for allowing the mid-infrared radiation emanating from the light-radiating endface to pass therethrough and for preventing OH diffusion therethrough toward the light-radiating endface. In another embodiment, an optical fiber product may include an optical fiber for propagation of mid-infrared radiation and an endcap coupled to the optical fiber for receiving therefrom the mid-infrared radiation and radiating out the mid-infrared radiation, the endcap being made of an endcap material that has no or a low amount of fluoride and that is less permeable to OH diffusion than the fiber-optic material.