Techniques for producing a Brillouin laser are provided. According to some aspects, techniques are based on forward Brillouin scattering and a multimode acousto-optic waveguide in which light is scattered between optical modes of the waveguide via the Brillouin scattering. This process may transfer energy from a waveguide mode of pump light to a waveguide mode of Stokes light. This process may be referred to herein as Stimulated Inter-Modal Brillouin Scattering (SIMS). Since SIMS is based on forward Brillouin scattering, laser (Stokes) light may be output in a different direction than back toward the input pump light, and as such there is no need for a circulator or other non-reciprocal device to protect the pump light as in conventional devices.

A compact, portable Raman spectrometer makes fast, sensitive standoff measurements at little to no risk of eye injury or igniting the materials being probed. This spectrometer uses differential Raman spectroscopy and ambient light measurements to measure point-and-shoot Raman signatures of dark or highly fluorescent materials at distances of 1 cm to 10 m or more. It scans the Raman pump beam(s) across the sample to reduce the risk of unduly heating or igniting the sample. Beam scanning also transforms the spectrometer into an instrument with a lower effective safety classification, reducing the risk of eye injury. The spectrometer's long standoff range automatic focusing make it easier to identify chemicals through clear and translucent obstacles, such as flow tubes, windows, and containers. And the spectrometer's components are light and small enough to be packaged in a handheld housing or housing suitable for a small robot to carry.

An optic produces a beam of ultraviolet laser radiation from a beam of visible laser radiation and spatially separates the ultraviolet laser beam from the visible laser beam. The optic includes two crystals made of the same optically-nonlinear material that are contact bonded along a planar interface. One crystal has principle crystal axes that are oriented for type-I second-harmonic generation. The ultraviolet laser beam exits the optic through an uncoated surface of the other crystal. The principle crystal axes of the two crystals have different orientations and have reflection symmetry about the planar interface.

An optic produces a beam of ultraviolet laser radiation from a beam of visible laser radiation and spatially separates the ultraviolet laser beam from the visible laser beam. The optic includes two crystals made of the same optically-nonlinear material that are contact bonded along a planar interface. One crystal has principle crystal axes that are oriented for type-I second-harmonic generation. The ultraviolet laser beam exits the optic through an uncoated surface of the other crystal. The principle crystal axes of the two crystals have different orientations and have reflection symmetry about the planar interface.

Disclosed is a terahertz laser device based on phonon vibration excitation, including a resonant cavity composed of a hollow waveguide made of a composite film and optical lenses at both ends of the waveguide, where M represents nano-metal particles. A zinc oxide mesomorphic microsphere is used herein as a source, symmetric stretching vibration of nanosheets on the zinc oxide microsphere is excited and induced by a laser and is transmitted through elastic and electric coupling among the nanosheets, and a terahertz wave with a frequency of 0.36 THz is radiated by means of phonon vibration; moreover, the zinc oxide mesomorphic microspheres and the nano-metal particles are mixed evenly to produce a strong local electric field a few nanometers nearby a surface of the metal particle by taking advantage of a surface-enhanced Raman effect of the nano-metal particles, a nanocantilever of the ZnO mesomorphic microsphere is greatly changed in polarizability with ample contact of the nano-metal particles and the ZnO mesomorphic microspheres, and thus the terahertz radiation power thereof is enhanced.

An optical element may include a plurality of subsurface induced scattering centers formed in the optical element, where the plurality of subsurface induced scattering centers scatter light passing through the optical element. In some implementations, the plurality of subsurface induced scattering centers may form a scattering region in the optical element. Additionally, or alternatively, the plurality of subsurface induced scattering centers may spatially vary transmission of light through the optical element. The optical element may be an optical waveguide, a bulk optic, and/or the like.

A method of inducing light losses at a parasitic wavelength in a fiber laser system includes providing a wavelength discriminator (WD) spaced from and between feeding and process fibers or from the end output of the feeding fiber so as to induce losses of light at parasitic wavelength. The device implementing the disclosed method is configured with a laser source, the delivery fiber and WD spaced at a distance between the surface to be treated and the end of the delivery fiber, wherein the WD receives the parasitic light over free space and is configured as a dichroic filter inducing losses to the light at the parasitic wavelength.

An optic produces a beam of ultraviolet laser radiation from a beam of visible laser radiation and spatially separates the ultraviolet laser beam from the visible laser beam. The optic includes two crystals made of the same optically-nonlinear material that are contact bonded along a planar interface. One crystal has principle crystal axes that are oriented for type-I second-harmonic generation. The ultraviolet laser beam exits the optic through an uncoated surface of the other crystal. The principle crystal axes of the two crystals have different orientations and have reflection symmetry about the planar interface.

A laser light source includes a nonlinear optical medium and a pump laser source configured to generate a pump laser beam to form a signal beam and an idler beam in the nonlinear optical medium by parametric down conversion. The laser light source further includes a seed light source configured to generate a seed signal beam and/or a seed idler beam having a coherence length lesser than a coherence length of the pump laser beam, and a superpositioning device configured to superposition the seed signal beam and/or the seed idler beam with the pump laser beam for joint coupling into the nonlinear optical medium.

A method of inducing light losses at a parasitic wavelength in a fiber laser system includes providing a wavelength discriminator (WD) spaced from and between feeding and process fibers or from the end output of the feeding fiber so as to induce losses of light at parasitic wavelength. The device implementing the disclosed method is configured with a laser source, the delivery fiber and WD spaced at a distance between the surface to be treated and the end of the delivery fiber, wherein the WD receives the parasitic light over free space and is configured as a dichroic filter inducing losses to the light at the parasitic wavelength.