Abstract: A multi-channel optical frequency mixer for all-optical signal processing and a method for engineering the same. The multi-channel mixer uses a nonlinear optical material exhibiting an effective nonlinearity deff whose spatial distribution is defined by a quasi-phase-matching grating, e.g., a QPM grating. The spatial distribution is defined such that its Fourier transform to the spatial frequency domain defines at least two wavelength channels which are quasi-phase-matched for performing optical frequency mixing. The wavelength channels correspond to dominant Fourier components and the Fourier transform is appropriately adjusted using grating parameters such as grating periods, phase reversal sequences and duty cycles to include an odd or even number of dominant Fourier components. The multi-channel mixer can perform frequency mixing operations such as second harmonic generation (SHG), difference frequency generation (DFG), sum frequency generation (SFG), and parametric amplification.

Abstract: Methods and apparatus are shown for cladding grown single crystal optical fibers. Neodymium YAG fibers are clad with a high index glass, either melted around the fiber in a trough or extruded over the fiber surface. Lithium niobate fibers are clad through an impregnation process. The lithium niobate fiber is first coated with magnesium oxide and then heated to a temperature and for a time sufficient for the magnesium oxide dopant material to diffuse into the fiber. The dopant lowers the intrinsic refractive indices of the fiber material around its circumference, creating a cladding region around the fiber core. Single crystal fibers clad by these methods and combined with suitable pumping means or with deposited electrodes provide low-loss single mode optical components useful for amplification, electro-optical effects and acousto-optical effects.

Abstract: Methods and apparatus are shown for cladding grown single crystal optical fibers. Neodymium YAG fibers are clad with a high index glass, either melted around the fiber in a trough or extruded over the fiber surface. Lithium niobate fibers are clad through an impregnation process. The lithium niobate fiber is first coated with magnesium oxide and then heated to a temperature and for a time sufficient for the magnesium oxide dopant material to diffuse into the fiber. The dopant lowers the intrinsic refractive indices of the fiber material around its circumference, creating a cladding region around the fiber core. Single crystal fibers clad by these methods and combined with suitable pumping means or with deposited electrodes provide low-loss single mode optical components useful for amplification, electro-optical effects and acousto-optical effects.