Abstract: Provided are methods of patterning porous materials on the micro- and nanometer scale using a direct imprinting technique. The present methods of direct imprinting of porous substrates (“DIPS”), can utilize reusable stamps that may be directly applied to an underlying porous material to selectively, mechanically deform and/or crush particular regions of the porous material, creating a desired structure. The process can be performed in a matter of seconds, at room temperature or higher temperatures, and eliminates the requirement for intermediate masking materials and etching chemistries.

Abstract: Diffraction gratings comprising a substrate with protrusions extending therefrom. In one embodiment, the protrusions are made of a porous material, for example porous silicon with a porosity of greater than about 10%. The diffraction grating may also be constructed from multiple layers of porous material, for example porous silicon with a porosity of greater than about 10%, with protrusion of attached thereto. In some embodiments the protrusions may be made from photoresist or another polymeric material. The gratings are the basis for sensitive sensors. In some embodiments, the sensors are functionalized with selective binding species, to produce sensors that specifically bind to target molecules, for example chemical or biological species of interest.

Abstract: Provided are methods of patterning porous materials on the micro- and nanometer scale using a direct imprinting technique. The present methods of direct imprinting of porous substrates (“DIPS”), can utilize reusable stamps that may be directly applied to an underlying porous material to selectively, mechanically deform and/or crush particular regions of the porous material, creating a desired structure. The process can be performed in a matter of seconds, at room temperature or higher temperatures, and eliminates the requirement for intermediate masking materials and etching chemistries.

Abstract: Diffraction gratings comprising a substrate with protrusions extending therefrom. In one embodiment, the protrusions are made of a porous material, for example porous silicon with a porosity of greater than about 10%. The diffraction grating may also be constructed from multiple layers of porous material, for example porous silicon with a porosity of greater than about 10%, with protrusion of attached thereto. In some embodiments the protrusions may be made from photoresist or another polymeric material. The gratings are the basis for sensitive sensors. In some embodiments, the sensors are functionalized with selective binding species, to produce sensors that specifically bind to target molecules, for example chemical or biological species of interest.

Abstract: A device for transmitting radiation is provided. The device includes a glass optical waveguide having a core. A Bragg grating is at least partially formed within the core. Associated with the Bragg grating is a transmission spectrum that includes a band in which incident radiation is attenuated, the peak attenuation being at a wavelength .lambda.. The transmission spectrum of the Bragg grating is such that the full width at half maximum measured in transmission is greater than or equal to (1.5 nm/1558.5 nm) .lambda. and peak attenuation within the band is greater than or equal to 90% of full scale transmission. Attenuation exceeds 50% of the peak attenuation everywhere within the full width at half maximum of the transmission spectrum.

Abstract: An improved method for forming a Bragg grating in a photosensitive, optical waveguiding medium by exposure to an interference pattern formed by overlapping beams of actinic radiation. When Bragg gratings are formed according to methods of the prior art, these gratings tend to exhibit reflectivity spectra having, in addition to a central peak, a generally undesirable series of subsidiary peaks. These subsidiary peaks are caused by a wave interference effect. The inventive method modifies or eliminates the subsidiary peaks by spatially modulating the average refractive index of the grating, or by spatially modulating the grating period.

Abstract: Nonlinear optical systems are provided which exhibit an enhanced nonlinear response to applied optical radiation. These systems are useful for processing radiation by nonlinear optical interactions, for example harmonic generation, mixing (sum and difference frequency generation), parametric oscillation, intensity dependent refractive index effects (focusing or lens formation) and perform various photonic functions (electro-optics). The systems utilize a materials system with an architecture in which inclusion components are distributed in a host component (preferably homogeneously). The host component has an optical response which varies nonlinearly with the amplitude of the optical field produced by the radiation applied to the composite material. The inclusion component is preferably particles which are less than a wavelength of the applied radiation in maximum dimension (diameter when the particles are spherical and length of major axis when the particles are generally ellipsoidal).