Abstract: The present invention extends the available spatial frequency content of an image through the use of a method and apparatus for combining nonlinear functions of intensity to form three dimensional patterns with spatial frequencies that are not present in either of the individual exposures and that are beyond 2/.lambda. in all three spatial directions. The resulting pattern has spatial frequency content beyond the limits set by optical propagation of spatial frequencies limited to 2/.lambda. (e.g. pitch reduction from .about..lambda./2 to at least .about..lambda./4). The extension of spatial frequencies preferably extends the use of currently existing photolithography capabilities, thereby resulting in a significant economic impact. Multiplying the spatial frequency of lithographically defined structures suitably allows for substantial improvements in, inter alia, crystal growth, quantum structure growth and fabrication, flux pinning sites for high-T.sub.

Abstract: Multiple-exposure fine-line interferometric lithography, combined with conventional optical lithography, is used in a sequence of steps to define arrays of complex, nm-scale structures in a photoresist layer. Nonlinearities in the develop, mask etch, and Si etch processes are used to modify the characteristics and further reduce the scale of the structures. Local curvature dependent oxidation provides an additional flexibility. Electrical contact to the quantum structures is achieved. Uniform arrays of Si structures, including quantum wires and quantum dots, are produced that have structure dimensions on the scale of electronic wave functions. Applications include enhanced optical interactions with quantum structured Si, including optical emission and lasing and novel electronic devices based on the fundamentally altered electronic properties of these materials. All of the process sequences involve parallel processing steps to make large fields of these quantum structures.

Abstract: Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

Abstract: In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer.

Abstract: A low-cost fabrication technique, readily extensible to volume manufacturing is presented for an electrooptically active fiber segment that can be simply integrated into optoelectronic devices. The fabrication technique offers a dielectric isolation structure surrounding the fiber to allow high field poling, a pair of electrodes used both for poling and for inducing an electrooptic effect, and ends of the fiber unaffected by the fabrication and available for splicing with additional fiber sections. The technique is readily adaptable to specialized electrode structures including striplines and/or microstrip lines for high frequency applications and segmented electrodes for quasi-phasematched three-wave mixing applications. By combining the electrooptically active fiber segment with other fibers in an integrated fiber modulator, high frequency modulation of an optical signal may be achieved with applications in telecommunications.

Abstract: Silicon MSM photodiodes sensitive to radiation in the visible to near infrared spectral range are produced by altering the absorption characteristics of crystalline Si by ion implantation. The implantation produces a defected region below the surface of the silicon with the highest concentration of defects at its base which acts to reduce the contribution of charge carriers formed below the defected layer. The charge carriers generated by the radiation in the upper regions of the defected layer are very quickly collected between biased Schottky barrier electrodes which form a metal-semiconductor-metal structure for the photodiode.

Abstract: A displacement measuring method and device is disclosed in which speckle amplitude interferometry within a single speckle feature or a small number of features of a speckle pattern is used to achieve sub-fringe accuracy with a single detector and to measure displacement of the object under investigation with sub-wavelength accuracy at measurement speeds consistent with real-time control of manufacturing processes. The same technique applied to multiple spots on a sample with optical means for causing interference between different combinations of scattered fields, including fields from different illuminated spots, permits measurements of the total sample motion.

Abstract: In microelectronic processing, the method of producing complex, two-dimensional patterns on a photosensitive layer with dimensions in the extreme submicron range. A photosensitive layer is first exposed to two beams of coherent radiation to form an image of a first interference pattern on the surface of the layer. The layer is subsequently exposed to one or more interference pattern(s) that differ from the first interference pattern in some way, such as by varying the incident angle of the beams, the optical intensity, the periodicity, rotational orientation, translational position, by using complex amplitude or phase masks in one or both of the coherent beams, or a combination of the above. Desired regions of the complex pattern thus produced are isolated with a further exposure of the photosensitive layer using any conventional lithography.

Abstract: In the manufacture of microelectronic and optoelectronic circuitry, an arrangement for aligning submicrometer lithographic features on a wafer illuminating a diffraction grating on the wafer with an interferometrically established radiation intensity pattern having a predetermined relationship to the lithographic features in another level of the wafer that is to be exposed, the radiation diffracted from the illuminated grating forming moire interference pattern providing spatial amplification of the grating period for alignment purposes by the ratio of the moire fringe spacing to the grating period.

Abstract: A large second order nonlinearity is induced in SiO.sub.2 portions of a waveguide enabling inducement of second order harmonic waves in the waveguide for numerous applications in integrated optics and optoelectronics.

Abstract: The method of measuring the relative between submicron lithographic features on a wafer having thereon a reference characteristic associated with a reference submicron grating structure of periodicity p.sub.1 onto which there may be cast from a reticle the image of a projected submicron grating structure of different periodicity p.sub.2 comprising measuring the extent of change in a moire fringe pattern produced by the superposition of the two grating structures on the wafer.

Abstract: The invention provides a position sensor for detecting relative displacement between two elements, and includes an optical beam-producing source fixed to one of the elements, a semiconductor body fixed to a second element and arranged so that the beams impinge one surface of the semiconductor body, a planar sensor composed of a back-to-back diode photodetector positioned on the semiconductor surface, and readout means to monitor current generated by the sensor which gives a measure of the relative position between the element to which the semiconductor body is affixed.

Abstract: A wavelength resonant semiconductor gain medium is disclosed. The essential feature of this medium is a multiplicity of quantum-well gain regions separated by semiconductor spacer regions of higher bandgap. Each period of this medium consisting of one quantum-well region and the adjacent spacer region is chosen such that the total width is equal to an integral multiple of 1/2 the wavelength in the medium of the radiation with which the medium is interacting. Optical, electron-beam and electrical injection pumping of the medium is disclosed. This medium may be used as a laser medium for single devices or arrays either with or without reflectors, which may be either semiconductor or external.

Abstract: Isotopes are separated from an isotopically mixed molecular dopant dissolved in a cryogenic liquid. The solution is exposed to infrared laser light in order to selectively vibrationally excite a particular molecular species which contains the isotope or isotopes that are to be separated. The excited species then is reacted or dissociated to form recoverable reaction products rich in the isotope desired.

Abstract: Liquid mixtures are used as the active medium in two-photon resonant four-wave mixing processes to achieve efficient nonlinear conversion of infrared laser frequencies. The resonant energy levels involved in these four-wave mixing processes are Raman-active vibrational modes of a molecular species which is one of the major constituents of the liquid mixture. Additional molecular and/or atomic constituents are added to the active molecular species to adjust the dispersion of the medium to optimize the nonlinear process. Diluents further may be used to fine-tune the two-photon resonance parameters to better match available infrared laser sources.

Abstract: In microelectronic processing, the method of producing complex, two-dimensional patterns on a photosensitive layer with dimensions in the extreme submicron range. A photosensitive layer is first exposed to two beams of coherent radiation to form an image of a first interference pattern on the surface of the layer. The layer is subsequently exposed to one or more interference pattern(s) that differ from the first interference pattern in some way, such as by varying the incident angle of the beams, the optical intensity, the periodicity, rotational orientation, translational position, by using complex amplitude or phase masks in one or both of the coherent beams, or a combination of the above. Desired regions of the complex pattern thus produced are isolated with a further exposure of the photosensitive layer using any conventional lithography.

Abstract: In microelectronic processing, the method of producing complex, two-dimensional patterns on a photosensitive layer with dimensions in the extreme submicron range. A photosensitive layer is first exposed to two beams of coherent radiation to form an image of a first interference pattern on the surface of the layer. The layer is subsequently exposed to one or more interference pattern(s) that differ from the first interference pattern in some way, such as by varying the incident angle of the beams, the optical intensity, the periodicity, rotational orientation, translational position, by using complex amplitude or phase masks in one or both of the coherent beams, or a combination of the above. Desired regions of the complex pattern thus produced are isolated with a further exposure of the photosensitive layer using any conventional lithography.