A method of making a porous three-dimensional object. The method comprises: a) positioning a first layer of particles on a build plate; b) heating the first layer of particles sufficiently to fuse the particles together to form a first build layer having a first porosity; c) exposing the first build layer to a laser beam to form one or more pores, the exposed first build layer having a first modified porosity, the laser beam being emitted from an optical fiber; d) adjusting one or more beam characteristics of the laser beam prior to or during the exposing of the first build layer, the adjusting of the laser beam occurring prior to the laser beam being emitted from the optical fiber; e) positioning an additional layer of particles on the exposed first build layer; f) heating the additional layer of particles sufficiently to fuse the particles together to form a second build layer having a second porosity; g) exposing the second build layer to the laser beam to form one or more pores, the exposed second build layer having a second modified porosity, the laser beam being emitted from the optical fiber; h) adjusting one or more beam characteristics of the laser beam after fusing the particles to form the second build layer and prior to or during the exposing of the second build layer, the adjusting of the laser beam occurring prior to the laser beam being emitted from the optical fiber, and i) repeating e), f), optionally g) and optionally h) to form a three-dimensional object.

An all-solid-state single-frequency continuous wave laser is provided, which includes a symmetric ring resonant cavity, a first gain crystal and a second gain crystal symmetrically arranged in the symmetric ring resonant cavity, and a gain unit symmetrically arranged between the first gain crystal and the second gain crystal. The gain unit includes at least one gain crystal arranged in sequence. In the gain unit, a third gain crystal nearest to the first gain crystal and a fourth gain crystal nearest to the second gain crystal are symmetrically arranged. Each gain crystal is coupled with a separate pump source. Each gain crystal in the symmetric ring resonant cavity is equipped with a separate pump source, and the imaging system is eliminated in the symmetric ring resonant cavity. On the premise that the pump power is not limited, the laser can achieve stable single-frequency operation in a wide pump range.

In various example embodiments, hybrid waveguide devices are disclosed based on a silicon nitride waveguide conformally coated with a tellurium oxide layer. A tellurium oxide layer is deposited over a silicon nitride waveguide such that the tellurium oxide layer forms a conformal layer that inherits the underlying shape of the silicon nitride waveguide, thereby forming a conformal raised region above the silicon nitride waveguide, while also forming planar regions that extend laterally from the silicon nitride waveguide. The present example hybrid waveguide structures enable the formation of a guided single mode that extends from the raised region of the tellurium oxide layer that resides above the silicon nitride waveguide into the silicon nitride waveguide, and the dimensions of the structure may be selected such that a majority of the optical mode is confined within the tellurium oxide layer, at least over a portion of the infrared region.

Disclosed is a planar waveguide including: a core (11) which is a flat plate through which light propagates; a cladding (12) which is a flat plate for reflecting the light in a state of being joined to an upper surface of the core (11); and a cladding (13) which is a flat plate for reflecting the light in a state of being joined to a lower surface of the core (11), in which each of the claddings (12) and (13) is a multilayer film in which multiple films made from different materials are layered. As a result, a material having a low index of refraction can be used as the material of the core (11), and the limit on materials usable as the material of the core (11) is relaxed.

A Raman Laser device having an nth Stokes shifted output the device including: a laser pump input; a lasing cavity having feedback elements at each end; and a diamond Raman active gain medium within the cavity, exhibiting first and higher Stokes emissions when subjected to pumping by the laser pump input; wherein the feedback elements feeding back the pump input, and 1st Stokes output from the gain medium, and a gain portion of the higher Stokes outputs, with a transmitting portion of the nth Stokes output being the output of the device.

The invention relates to rare-earth-doped ternary sulfides. The rare-earth-doped ternary sulfides may be used as an active material for mid-wave infrared and long-wave infrared lasers and amplifiers. Methods for producing laser materials including rare-earth-doped ternary sulfides, as well as lasers and amplifiers incorporating the laser materials, are also provided.

An infrared detection system comprises the following elements. A laser source provides radiation for illuminating a target (5). This radiation is tuned to at least one wavelength in the fingerprint region of the infrared spectrum. A detector (32) detects radiation backscattered from the target (5). An analyser determines from at least the presence or absence of detected signal in said at least one wavelength whether a predetermined volatile compound is present. An associated detection method is also provided. In embodiments, the laser source is tunable over a plurality of wavelengths, and the detector comprises a hyperspectral imaging system. The laser source may be an optical parametric device has a laser gain medium for generating a pump beam in a pump laser cavity, a pump laser source and a nonlinear medium comprising a ZnGeP.sub.2 (ZGP) crystal. On stimulation by the pump beam, the ZnGeP.sub.2 (ZGP) crystal is adapted to generate a signal beam having a wavelength in a fingerprint region of the spectrum and an idler beam having a wavelength in the mid-infrared region of the spectrum. The laser gain medium and the ZnGeP.sub.2 (ZGP) crystal are located in the pump wave cavity.

Disclosed is a planar waveguide including: a core (11) which is a flat plate through which light propagates; a cladding (12) which is a flat plate for reflecting the light in a state of being joined to an upper surface of the core (11); and a cladding (13) which is a flat plate for reflecting the light in a state of being joined to a lower surface of the core (11), in which each of the claddings (12) and (13) is a multilayer film in which multiple films made from different materials are layered. As a result, a material having a low index of refraction can be used as the material of the core (11), and the limit on materials usable as the material of the core (11) is relaxed.

The present disclosure relates to tellurite crystals, growing methods of the same, and applications thereof; the crystals a chemical formula of MTe.sub.3O.sub.8, wherein M=Ti, Zr, Hf, which belongs to an Ia-3 space group of a cubic crystal system, wherein a transmittance waveband ranges from visible light to infrared light, with a transparency 70%. According to the present disclosure, a growing method of a tellurite crystal is provided, wherein the crystal may be grown using a flux method, a Czochralski method, or a Bridgman-Stockbarger method. The tellurite crystals may be used as an acousto-optic crystal for fabricating an optical modulation device. The present disclosure takes the lead internationally in growing the tellurite single crystals, the size and quality of which sufficiently meet the demands of practical applications of the tellurite single crystals.

The laser element includes a gain medium and a photochromic compound that receives a carrier from the gain medium. The gain medium may contain: a first ion including at least one selected from the group consisting of an alkali metal ion, an ammonium ion, a formamidinium ion, a guanidium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, and a protonated thiourea ion; a second ion including at least one selected from the group consisting of lead, germanium, tin, antimony, and bismuth; and an anion or a ligand including at least one selected from the group consisting of a chloride ion, a bromide ion, an iodide ion, a cyanide ion, a thiocyanate, an isothiocyanate, and a sulfide.