Abstract: A tunable laser system comprises an externalcavity laser diode in combination with an optically coupled waveguide having a Bragg grating formed therein. The laser diode provides a gain medium characterized by a first band of wavelengths. A portion of the fiber and the grating help define an external resonant cavity. The grating limits the wavelengths exiting the external cavity to a second band that is typically much narrower than the first band. The grating region of the waveguide is thermally coupled to a heating element having an associated temperature controller for controllably varying the temperature of the grating region and thus changing the optical pitch of the grating and thus the second band. The grating region of the waveguide can alternatively, or additionally, be subjected to acoustic energy to change the optical pitch of the grating.

Abstract: An optical routing element (ORE) that can be incorporated into a variety of configurations, to provide the basis for such devices as crossbar switches, wavelength division multiplexers, and add/drop multiplexers. The ORE includes first, second, and third waveguide segments. The first and second waveguide segments extend along a common axis, and are separated by a routing region. The third waveguide segment extends from the routing region at a non-zero angle with respect to the common axis. The routing region is occupied by a selectively reflecting element that selectively reflects light based on a state of the element or a property of the light. The selectively reflecting element may be a thermal expansion element (TEE) or a wavelength-selective filter. A TEE has a body of material having contracted and expanded states at respective first and second temperatures.

Abstract: A fiber optic switch module that can be incorporated into switch designs characterized by negligible crosstalk. The switch module is capable of operation over two wavelength bands. A 2.times.2 switch module has an open or bar state in which polished portions of the fiber segments are separated from each other and a closed or cross state where the polished portions are in optical contact with each other. The module has arbitrarily low crosstalk in the bar state, but typically some crosstalk in the cross state. In one embodiment, the third port of a first 2.times.2 module is coupled to the first port a second 2.times.2 module while no connections are-made to the second ports of the modules or to the third port of the second module.

Abstract: An attenuating centrosymmetric reflective (CSR) device is provided for controllably coupling optical energy between pairs of optical fibers. The CSR-based attenuating device comprises a CSR coupler having a neutral density attenuating plate inserted between a fiber holder portion of the device and the reflecting mirror. The attenuating plate is preferably of variable density so that translation of the attenuating plate across the path of the beams results in varying attenuation. In a specific embodiment, back reflections to the source are eliminated by positioning the variable density attenuator plate at an angle large enough so that reflections of all reflected rays exceed the acceptance angle of the fiber ends. The variable density attenuating plate may be manually or automatically moved to obtain the desired attenuation.

Abstract: A fiber optic isolator uses only one-half the amount of costly rotator material as the prior art and an isolated laser amplifier uses only one-quarter the amount of costly rotator material. An embodiment of a fiber optic isolator includes a concave reflector and a fiber holder defining first and second fiber ports that register the respective ends of first and second fibers. A polarizer is located between the first port and the reflector, an analyzer is located between the second port and the reflector, and a Faraday rotator is disposed between the polarizer and analyzer on one side and the reflector on the other side. The polarizer and analyzer have their polarization axes at a relative angle of 45.degree. while the rotator is configured to provide a 22.5.degree. rotation.

Abstract: The present invention provides modules for interfacing optical fibers with very low light loss and with provision for monitoring of the optical signal. The modules according to the present invention are characterized by the precise tolerances required in high capacity optical communication systems and yet may be mass produced at reasonable costs. A device according to the present invention comprises an imaging element having a curved reflective surface at one end and prealigned fiber insertion holes at the other end. Various embodiments of the invention are disclosed.

Abstract: Multiple reflection modules having as a light source or a light target a lensed optical fiber employ one more spherical reflectors and wavelength selectors for selecting the wavelengths of optical radiation on selected optical paths between said light source and said light target. The reflection module may be a multiplexer or a laser cavity. As a laser, it may include as a source a semiconductor laser comprising a laser source disposed to direct radiation through a first multiple layer dielectric Fabry-Perot cavity with the center of curvature between the source and a fiber tip to which output energy is to be coupled, and a second reflector mounted behind the first reflector, the second reflector being a full reflector with the center of curvature at the laser source.

Abstract: A star coupler/monitor comprises a beam splitter (25) and at least one imaging element (30) oriented relative to first, second, and third spatially discrete regions (35a-c) as follows. A minor portion of the light emanating from any given point in the first region (35a) is imaged at a corresponding point in the second region (35b). A major portion of the light emanating from the given point is imaged at a corresponding point in the third region (35c). The ends of N input fibers in an input bundle (12) are registered in an array in the first region (35a). The ends of N monitor fibers in a monitor bundle (15) are registered fiber-by-fiber at optically conjugate locations in the second region (35b) so that a minor portion of the light emanating from any one of the input fibers is imaged at the corresponding monitor fiber end. An integrating element (17) such as a rod is disposed in the third region (35c).

Abstract: An alignment method and construction for fiber optics communication modules. A module includes a plano-convex element, a concave element , and a fiber-holding substrate. The plano-convex element has first and second surfaces. The first surface is flat; the second surface has a convex segment characterized by a self-conjugate plane coincident with the first surface and a surrounding flat segment parallel to the first surface. The concave element has a concave surface segment surrounded by a flat segment. When the flat segment of the concave element is bonded to the flat segment of the plano-convex element, the first surface of the latter is also a self-conjugate plane for the concave segment. The substrate has a first flat face that is bonded to the first surface of the plano-convex element and a second flat face having a fiber-receiving means therein. Batch assembly and alignment may be achieved by fabricating carrier elements containing arrays of the plano-convex elements or concave elements.

Abstract: Apparatus and a manufacturing method for a star coupler/monitor (10). A star coupler/monitor comprises a beam splitter (25) and at least one imaging element (30) oriented relative to first, second, and third spatially discrete regions (35a-c) as follows. A minor portion of the light emanating from any given point in the first region (35a) is imaged at a corresponding point in the second region (35b). A major portion of the light emanating from the given point is imaged at a corresponding point in the third region (35c). The ends of N input fibers in an input bundle (12) are registered in an array in the first region (35a). The ends of N monitor fibers in a monitor bundle (15) are registered fiber-by-fiber at optically conjugate locations in the second region (35b) so that a minor portion of the light emanating from any one of the input fibers is imaged at the corresponding monitor fiber end. An integrating element (17) such as a rod is disposed in the third region (35c).

Abstract: A fiber optics coupler module has a portion defining a spherical reflective surface characterized by a self-conjugate plane having the property that a point source of light in the self-conjugate plane is imaged in the self-conjugate plane. The coupler includes first and second optical transceiver terminals adapted to register a source, detector, or fiber end at each of first and second conjugate locations within the self-conjugate plane. The reflective surface passes a fraction of light incident thereon, whereupon a portion of light diverging from the first location passes through the reflective surface along a first optical path. Similarly a portion of light diverging from the second location passes through the reflective surface along a second optical path.

Abstract: The present invention provides modules for interfacing optical fibers with very low light loss and with provision for monitoring of the optical signal. The modules according to the present invention are characterized by the precise tolerances required in high capacity optical communication systems and yet may be mass produced at reasonable costs. A device according to the present invention comprises a transparent imaging element having a curved reflective surface at one end and prealigned fiber insertion holes at the other end. The transparent element is characterized by an index of refraction equal to that of the fiber core, and the fibers are glued in their respective holes with index matching cement.

Abstract: An insulating window which has louvered radiant energy absorbing screen positioned in the airspace between inner and outer spaced apart window panes, said airspace connected at the top to electrically actuated dampers and blower in a duct system, and said airspace connected at the bottom to the interior of the room through an air filtering element. In the preferred embodiment, temperature sensors and electronic logic system provide control of air flow rate and valve settings to accomplish space heating, water heating and/or exterior venting of hot air as required by weather conditions and building heat demands.

Abstract: A solar energy collector is described which consists of either a photoelectric cell or a heat-absorbing material mounted within a hollow concentrator. The photoelectric cell has the form of a rod of a monocrystalline element or compound with a generally cylindrical junction spaced at a distance radially inwardly from the outer surface of the rod. The photoelectric cell is mounted within a hollow transparent trough shaped concentrator or body which contains a liquid, e.g. water, which can be made to flow in order to both cool the photoelectric cell, thereby improving its efficiency, and to promote transmission of solar energy to the photoelectric cell by total internal reflectance.

Abstract: A window portion is interposed between the incident light and a heat absorbing portion and at least one of the heat absorbing and window portions has a plurality of spaced apart reflecting surfaces, separate ones of which face each other and transmit the incident light by multiple reflections to the heat absorbing portion. In at least one embodiment, these opposed reflecting surfaces converge in the direction of light travel from the window portion to the heat absorbing portion and infrared reflecting means are interposed between the window portion and the heat absorbing portion to return infrared light emitted by the heat absorbing portion back to the heat absorbing portion.

Abstract: Light from a bulb is projected through the microfiche transparency by a condensor and a projection lens system and the projected image therefrom is passed through a prism to viewing screen means.

Abstract: A window portion is interposed between the incident light and a heat absorbing portion and at least one of the heat absorbing and window portions has a plurality of spaced apart reflecting surfaces, separate ones of which face each other and transmit the incident light by multiple reflections to the heat absorbing portion. In at least one embodiment, these opposed reflecting surfaces converge in the direction of light travel from the window portion to the heat absorbing portion and infrared reflecting means are interposed between the window portion and the heat absorbing portion to return infrared light emitted by the heat absorbing portion back to the heat absorbing portion.

Abstract: Light from a bulb is projected through the microfiche transparency by a condensor and a projection lens system and the projected image therefrom is passed through a prism to viewing screen means.

Abstract: The window panel includes a plurality of sets of reflecting surfaces which are spaced apart from and facing each other and which transmit the incident light at least in part by multiple reflections. The sets of reflecting surfaces are arranged parallel to each other in a panel. In at least one embodiment the sets of opposed reflecting surfaces converge in the direction of incident light travel through the window panel and infrared reflecting means are provided to reflect infrared light attempting to pass through the window panel in a direction opposite to the direction of travel of the incident light.