An apparatus includes a plurality of front-end nonlinear optical crystals and a plurality of back-end nonlinear optical crystals. The front-end nonlinear optical crystals are arranged in a chain and are configured to amplify a received signal. The back-end nonlinear optical crystals are arranged in the chain after the front-end nonlinear optical crystals and are configured to further amplify the received signal and generate an amplified signal. The back-end nonlinear optical crystals are made from a different nonlinear optical crystal than the front-end nonlinear optical crystals.

A method for fabricating an optical waveguide comprises: providing a sample of lithium niobate doped with magnesium oxide and having at least one grating of periodic domain inversion defined therein; applying a layer of metallic zinc to a surface of the sample over the at least one grating using sputter deposition; heating the sample in an atmosphere of pure oxygen to cause the zinc to indiffuse into the lithium niobate to form a waveguiding layer of increased refractive index under the surface of the sample; and using a dicing blade to cut two substantially parallel channels along a length direction of the at least one grating, to define a ridge waveguide between the two channels.

A nonlinear optical crystal of barium cesium borate, a preparation method and use thereof are provided. The nonlinear optical crystal has a chemical formula of CsBa.sub.3B.sub.11O.sub.20 and a molecular weight of 983.84. The nonlinear optical crystal belongs to an orthorhombic crystal system; a space group of the nonlinear optical crystal is Cmc2.sub.1; lattice parameters of the nonlinear optical crystal are a=19.011(7) Å, b=10.837(4) Å, c=8.578(3) Å, Z=4, V=1767.4(11) Å.sup.3; and a Mohs hardness of the nonlinear optical crystal is 4-5. The nonlinear optical crystal is grown by a flux method. The nonlinear optical crystal of the barium cesium borate obtained is used for a manufacture of non-linear optical devices. The nonlinear optical crystal has a large size of centimeter-scale at least and is prepared by fast, simple and low-cost operations. The nonlinear optical crystal prepared has a large size, a wide light transmission band and good mechanical properties.

An emission enhancement structure having at least one energy augmentation structure; and an energy converter capable of receiving energy from an energy source, converting the energy and emitting therefrom a light of a different energy than the received energy. The energy converter is disposed in a vicinity of the at least one energy augmentation structure such that the emitted light is emitted with an intensity larger than if the converter were remote from the at least one energy augmentation structure. Also described are various uses for the energy emitters, energy augmentation structures and energy collectors in a wide array of fields, including various adhesives applications.

An emission enhancement structure having at least one energy augmentation structure; and an energy converter capable of receiving energy from an energy source, converting the energy and emitting therefrom a light of a different energy than the received energy. The energy converter is disposed in a vicinity of the at least one energy augmentation structure such that the emitted light is emitted with an intensity larger than if the converter were remote from the at least one energy augmentation structure. Also described are various uses for the energy emitters, energy augmentation structures and energy collectors in a wide array of fields, such as color enhancement, and color enhancement structures containing the same.

A graphene structure includes one or more graphene layers. The graphene layers allow for microwave squeezing with gains up to 24 dB over a wide bandwidth.

A graphene structure includes one or more graphene layers. The graphene layers allow for microwave squeezing with gains up to 24 dB over a wide bandwidth.

A wavelength conversion device including a cavity that includes an RAMO.sub.4 crystal having a single crystal represented by a first general formula of RAMO.sub.4, a laser crystal, and a mirror, in which in the first general formula, R represents one or a plurality of trivalent elements selected from the group consisting of Sc, In, Y, and lanthanoid elements, A represents one or a plurality of trivalent elements selected from the group consisting of Fe (III), Ga, and Al, and M represents one or a plurality of divalent elements selected from the group consisting of Mg, Mn, Fe (II), Co, Cu, Zn, and Cd.

It remains a challenge to generate coherent radiation in the spectral range of 0.1-10 THz (“the THz gap”), a band for applications ranging from spectroscopy to security and high-speed wireless communications. Here, we disclose how to produce coherent radiation spanning the THz gap using efficient second-harmonic generation (SHG) in low-loss dielectric structures, starting from an electronic oscillator (EO) that generates coherent radiation at frequencies of about 100 GHz. The EO is coupled to cascaded, hybrid THz-band dielectric cavities that combine (1) extreme field concentration in high-quality-factor resonators with (2) nonlinear materials enhanced by phonon resonances. These cavities convert the input radiation into higher-frequency coherent radiation at conversion efficiencies of >10.sup.3%/W, making it possible to bridge the THz gap with 1 W of input power. This approach enables efficient, cascaded parametric frequency converters, representing a new generation of light sources extensible into the mid-IR spectrum and beyond.

A electronic method, includes receiving, by a graphene structure, a microwave signal. The microwave signal has a driving voltage level. The electronic method includes generating, by the graphene structure, optical photons based on the microvolts. The electronic method includes outputting, by the graphene structure, the optical photons.