Abstract: Two, operationally independent networks are established along a common transmission bus by having the signals for the respective networks propagate in opposite directions, and directionally coupling the station units of the respective networks to the transmission bus so as to receive and transmit signals in one of the two directions. The two networks can operate at different bit rates and wavelengths and, being operationally independent, can be installed and added to at different times.

Abstract: A new method for fabricating electret-containing devices is disclosed. The inventive method includes a new technique for fabricating electrets, which involves applying a voltage across an electrically polarizable body. Large-scale breakdown effects in the body are avoided by reducing the voltage across at least a portion of the body undergoing polarization in response to a current indicating the onset of a breakdown in the body.

Abstract: A multilayer dielectric optical waveguide (30, 40) is formed on a III-V semiconductor substrate layer (6) comprised of either InGaAsP or AlGaAs. A lower cladding layer (30) of dielectric material such as SiO.sub.x, (x.about.2) having a lower index of refraction than the substrate layer is directionally deposited on an exposed surface (17) of the substrate layer by a controlled evaporation process. A core layer (40) is fabricated on the lower cladding layer by coating an exposed surface (31) of the lower cladding layer with a dielectric material having an index of refraction greater than the index of the cladding layer. One material useful as the core layer is polyimide. Both one-dimensional (FIG. 8) and two-dimensional (FIG. 10) waveguides are capable of being made by appropriate addition of an upper cladding layer (50 or 60) about the core layer. The refractive index of the upper cladding layer is less than the refractive index of the core layer.

Abstract: The use of an anisotropic etchant containing BCl.sub.3 and a source of atomic chlorine for III-V semiconductor materials has yielded improved results for semiconductor devices. For example, via gallium arsenide field effect transistors produced using this anisotropic etchant to fabricate via holes exhibit excellent electrical characteristics.

Abstract: A photodetector, and a method for detecting electromagnetic radiation, is disclosed. The photodetector includes a body which undergoes a detectable, internal physical or chemical change when exposed to electromagnetic radiation, as well as means for detecting this change. The photodetector also includes a substantially periodic surface which increases the efficiency with which incident electromagnetic radiation is coupled onto the photodetector.

Abstract: A photodetector, and a method for detecting electromagnetic radiation, is disclosed. The photodetector includes a body which undergoes a detectable, internal physical or chemical change when exposed to electromagnetic radiation, as well as means for detecting this change. The photodetector also includes a substantially periodic surface which increases the efficiency with which incident electromagnetic radiation is coupled onto the photodetector.

Abstract: Photosensitive bodies that are sensitive to ultraviolet radiation and that exhibit excellent contrast are formed from base soluble polymers such as poly(methyl methacrylate-co-methacrylic acid) physically mixed with base insoluble materials such as o,o'-dinitrobenzyl esters. The base insoluble esters decompose upon irradiation to form base soluble entities in the irradiated regions. These irradiated portions are then soluble in basic solutions that are used to develop the desired image.

Abstract: The invention involves a new sensitizing bath for chalcogenide glass-based resists. The inventive bath is alkaline and contains a silver complex whose ligand includes hydrophobic and hydrophilic moieties. Upon immersing a chalcogenide glass in the bath, a silver composition-containing film is formed on the surface of the glass. This film is substantially free of pin holes and has a uniform thickness which is insensitive to immersion time and largely determined by the pH of the bath.

Abstract: A matrix addressed, bistable liquid crystal optical display is disclosed. The display includes a liquid crystal twist cell which has at least two states which are stable in the presence of a single given holding voltage. A form of 3:1 matrix addressing is used in the display which enhances operational characteristics.

Abstract: Single longitudinal mode operation is achieved and maintained under CW and high speed (Gbps) current modulation conditions by a short coupled cavity laser including a short cavity semiconductor laser having two parallel mirror facets and a reflective surface spaced apart from and in predetermined relationship with one of the mirror facets. A short external cavity resonator is formed between the one mirror facet and the reflective surface. In general, the laser cavity length is related to the external cavity resonator length by the equation, nL=md, where nL is the effective optical length of the injection laser, d is the length of the external cavity resonator, and m is a positive number preferably between 2 and 10.

Abstract: A method and apparatus for fabricating a device is disclosed, which method involves a new reactive ion etching technique. Both a high etch rate and, for example, a high etch selectivity are simultaneously achieved with the inventive reactive ion etching technique by discharging an electrode of the reactive ion etching apparatus in response to a preselected criterion, e.g., a magnitude of a DC bias at said electrode which equals, or exceeds, a preselected value.

Abstract: Various techniques for examining the core region of optical fibers and fiber preforms involve placing a portion of the fiber/preform in an index-matching fluid and transversely illuminating the immersed portion. As described herein, the use of an index-matching fluid can be eliminated by illuminating the fiber/preform with a diverging beam. By the suitable selection of parameters, refraction at the air-fiber/preform interface can produce a well colliminated beam within the core region.

Abstract: A method for lithographically fabricating devices is disclosed. In accordance with the method, a sacrificial coating material (SCM), e.g., a resist, mixed with a fluorescent material is deposited onto a substrate and then etched. SCM etching is monitored by subjecting the fluorescent material within the SCM to fluorescence-inducing energy, and detecting the resulting fluorescence. Because the fluorescent material is etched away as the SCM is etched, fluorescence intensity decreases as SCM thickness is reduced. Thus, SCM etch end point is accurately determined because etch end point corresponds to the point in time when the detected fluorescence ceases.

Abstract: A method for fabricating a device which includes a tantalum silicide structure, and which is essentially free of conductive etch residues, is disclosed. The method includes the steps of depositing tantalum and silicon onto a substrate, patterning the tantalum and silicon, and then sintering the patterned tantalum and silicon to form a patterned layer of tantalum silicide.

Abstract: Solid state electronic devices are optically monitored during fabrication to detect hot spots which are indicative of faulty operation. The surface temperatures of such a device are measured by applying a fluorescent material to the device, and subsequently monitoring the temperature dependent fluorescence of the material, which is reflective of the temperature of the underlying device. Devices are accepted, rejected, or further processed in response to the monitored fluorescence.

Abstract: A method and apparatus for measuring etch depth during the etching of a device pattern into a nontransparent substrate, is disclosed. The method makes use of the finding that the device patterns etched into substrates produce diffraction patterns when illuminated. Thus, according to the method, a beam of light is directed onto a region of a substrate, into which region a portion of a device pattern is being etched. The light reflected from this region forms a diffraction pattern and, according to the inventive method, the intensity of a diffraction order is detected and recorded as a function of time during the etching procedure. The intensity of the diffraction order varies with time. The etch rate of the substrate is inversely proportional to the period of the oscillations in the recorded intensity-time curve.

Abstract: A method for enhancing linewidth control during the patterning of a substrate with a resist is disclosed. Resists used in the invention have chemically separated structures characterized by two types of regions of different chemical composition, which different types of regions are interspersed among each other. Because the resists used in the present invention have chemically separated structures, anisotropic wet development of these resists is achievable with an appropriate bicomponent wet developer. Consequently, after exposure, the image formed in a thin, upper layer of the resist is transferred with vertical walls through the thickness of the resist.

Abstract: A means for aligning components of an optical system without the use of conventional optical equipment is disclosed. This means includes the use of a pair of electrodes in proximity with the light guiding portion of a pyroelectric system element. The absorption of light in the waveguide produces a current in the pyroelectric material tht is monitored at the electrodes. Alignment of the system components is achieved by adjusting their relative position to increase the monitored signal.

Abstract: The use of an anisotropic etchant containing BCl.sub.3 and a source of atomic chlorine for III-V semiconductor materials has yielded improved results for semiconductor devices. For example, via gallium arsenide field effect transistors produced using this anisotropic etchant to fabricate via holes exhibit excellent electrical characteristics.

Abstract: Photosensitive bodies that are sensitive to ultraviolet radiation and that exhibit excellent contrast are formed from base soluble polymers such as poly(methyl methacrylate-co-methacrylic acid) physically mixed with base insoluble materials such as o-nitrobenzyl esters. The base insoluble esters decompose upon irradiation to form base soluble entities in the irradiated regions. These irradiated portions are then soluble in basic solutions that are used to develop the desired image.