Abstract: An apparatus is provided that allows the tunability of a waveguide bench router with a silicon-based material. This is accomplished by adding a triangular shaped layer of hydrogenated amorphous silicon (a-Si:H) as an active region across the waveguide. By varying a current across the triangle, the refractive index of the layer will change causing a change to the delay of the signal going across the material. Thus eliminated are the need for Group III-V elements or Lithium Niobate as the tunable element, increasing the coupling efficiency and decreasing cost.

Abstract: Pulse broadening in a single mode optical transmission system due to wavelength dispersion is reduced by separating the different wavelength components and selectively delaying them. Upon recombination, the original phases of the wavelength components are restored, and the pulses narrowed. By using exclusively single mode devices, essentially lossless operation is realized.

Abstract: The present invention is directed at an electrically tunable filter for wavelength filtering of light. The filter comprises a substrate region, a waveguide region over the substrate, an upper region over the waveguide region, and current blocking regions adjacent to the waveguide region. The waveguide region comprises a semiconductor having a bandgap wavelength sufficiently different from the light for high peak transmission of the light. A waveguide rib layer may also be included in the waveguide region to channel the light through the filter. The current blocking regions narrow the waveguide region to increase the current density. The present invention is also directed at a method of manufacturing the filter described above.

Abstract: Both the fiber and the bulk Fabry-Perot etalons can be made temperature insensitive by the addition of a compensator element. This element adjusts the optical length of the air-gap in the etalon cavity so as to compensate for any changes in the optical length of the fiber or the etalon slab due to ambient temperature changes.

Abstract: A compact all-fiber, electrically tunable ring laser includes a diode-pumped erbium-doped fiber amplifier. The frequency of the laser is tuned by a fiber Fabry-Perot (FFP) etalon that is electrically tuned. An in-line optical isolator is used in conjunction with the FFP to eliminate undesired reflections. A second FPP with a narrow free spectral range (FSR) can be used in conjunction with a first FFP with a wide FSR.

Abstract: A compact all-fiber, electrically tunable ring laser includes a diodepumped erbium-doped fiber amplifier. The frequency of the laser is tuned by a fiber Fabry-Perot(FFP) etalon that is electrically tuned. An in-line optical isolator is used in conjunction with the FFP to eliminate undesired reflections. A second FFP with a narrow free spectral range (FSR) can be used in conjunction with a first FFP with a wide FSR.

Abstract: This invention is a highly efficient star coupler for use with single mode waveguides. In the inventive coupler, all of the input waveguides and all of the output waveguides are assembled to form two separate bundles. The two bundles are axially aligned with each other and the ends of the bundles are spaced apart. The ends of the waveguides of the bundle of output waveguides are polished to receive optical energy from the bundle of input waveguides. The end facet of the input waveguide bundle is shaped and polished to form a convex spherical surface. The diameter of each waveguide of the bundle is small relative to the diameter of the bundle of waveguides. Therefore, the end facet of each waveguide which makes up the convex spherical surface is angled very slightly relative to the waveguide axis. This slight angle on the end facet of the waveguide acts as a bevel to bend the optical energy coming out of the end of the waveguide.

Abstract: In this invention there is disclosed an optical filter disposed on an optical fiber. More specifically, a filter comprised of a multilayer thin-film stack of low and high index of refraction material is deposited onto the end of an optical fiber. The filter can be, for example, a long-pass filter, a Fabry-Perot Etalon, a Double-Cavity Filter, and the like. Filters deposited on perpendicular facets of single-mode fibers reflect most of the power that is not transmitted. This reflection if fed back to a laser or an amplifier can cause a problem, particularly if an isolator does not adequately block the reflections. A bevel on the fiber end face can eliminate this problem by preventing the reflected power from being directed back into the optical fiber.

Abstract: One aspect of the invention is a Fabry-Perot cavity which has in part a waveguiding portion and in part a nonwaveguiding portion. In this manner, a cavity is constructed whose length would be too short to manipulate effectively if it were comprises exclusively of a waveguiding portion, and whose length might have unacceptable diffraction losses if it were comprised exclusively of a nonwaveguiding portion. In the inventive device the resonant wavelength can be adjusted by varying the length of either the gap or the waveguide or both. The device can be advantageously constructed and aligned using fiber coupling technology.

Abstract: The invention is an optical isolator. In one embodiment the optical isolator comprises two linear polarizers, one at the input of the isolator and the other at the output. Positioned between the input and the output linear polarizer is a gyrotropic medium located within a resonant cavity such as a Fabry-Perot cavity. Interposed between the linear polarizer at the input of the isolator and the resonant cavity is a first polarization conversion means for converting received plane polarized optical energy from said linear polarizer to circularly polarized optical energy and interposed between the resonant cavity and the linear polarizer at the output of the isolator is a second polarization conversion means for converting received circular polarized optical energy from said resonant cavity to plane polarized optical energy. In an embodiment, the resonant cavity comprising the gyrotropic medium becomes the filtering medium to block reflected optical radiation.

Abstract: This invention is a new type of Fabry-Perot cavity, and an optical communication system using such a cavity. The inventive Fabry-Perot cavity comprises both a waveguiding portion and a nonwaveguiding portion. In this manner, tunable cavities of desirable mid-range length, necessary to obtain required free spectral ranges, may be fabricated with minimal diffraction losses otherwise associated with cavities of such length. The cavity length may be varied using, for example, piezoelectric elements, and the various cavity elements may be aligned and connected, using fiber connector technology.

Abstract: A practical, manufacturable Fabry-Perot etalon and method for fabricating the same is disclosed. The plastic coating material is removed from the ends of a predetermined length of single mode fiber. A small area of the glass fiber is exposed by scraping away the coating near the center of the fiber on one side, and the fiber is then broken at this point forming a small gap. The remaining coating holds the broken fiber together and automatically matches the pieces in alignment. Mirrors of desired relfectivity are applied to the polished fiber ends, either by gluing on discrete mirrors or by applying multilayer dielectric coatings. The fiber/mirror structure is mounted onto a piezoelectric substrate. A voltage is applied to the piezoelectric substrate, causing longitudinal expansion of the fiber gap and providing the scanning means to obtain a spectrum of resonant wavelengths.

Abstract: The present invention relates to a technique for infusing and maintaining a gas-in-glass fiber. In the present technique, a length of an optical fiber, e.g., a single mode fiber, is placed in a pressure vessel with the ends of the fiber protruding from the vessel walls through seals. The vessel is then partially or fully filled with a medium, such as a gas or water, and the vessel sealed. In one embodiment, a container, including both the predetermined gas under pressure and a rupture disc in a container wall, is disposed within the vessel. Pressure is then applied to the sealed vessel until the rupture disc implodes and releases the gas for subsequent infusion. In a second embodiment, the predetermined gas is introduced into the vessel from an outside pressurized source until a first predetermined pressure is obtained within the vessel. A predetermined amount of additional pressure from a second pressure source is then supplied to the vessel until a second predetermined pressure is reached in the vessel.

Abstract: The dispersion in an optical fiber is determined using an intensity or optical signal envelope cross-correlation. Light from an optical source is injected into two transmission paths in which the relative delay can be varied. At least one path comprises the optical fiber whose dispersion is to be determined. Each path provides an output signal having a signal envelope. These envelopes are then cross-correlated for a number of wavelengths to provide a measurement of group delay from which the dispersion is determined.

Abstract: A new Raman gain medium, comprising an optical fiber into which molecular gas has been diffused, is disclosed. This new medium combines the advantages of a fiber, i.e., long interaction path, low loss, controllable dispersion, and convenience in handling, with the large Raman wave number shift of the gas, i.e., 4136 cm.sup.-1 for H.sub.2 in silica. A laser made with such a medium can provide a relatively high power, tunable, coherent signal source in the near and far infrared regions.

Abstract: A method for manufacturing silica-based optical fiber, and for manufacturing optical fiber preforms, the method comprising deuterium/hydrogen exchange in the silica-based material carried out subsequent to formation of the silica.

Abstract: A dye laser (FIG. 1, 5 or 6) includes a pumping laser source (e.g. 11), an optical resonator (e.g. 13-15), and a dye solution or dye cell (e.g. 12) disposed in the path of the pumping laser light in the resonator. The dye cell disclosed herein comprises a pair of closely spaced transparent discs (21). A motor (26) serves to spin the discs at a high rate of speed. The pumping laser light in the resonator is focused on the discs at a predetermined angle (i.e. the Brewster angle). New, unbleached dye is injected axially with respect to the discs so that the spin force causes a radial flow of the dye solution between the spinning discs and, of course, past the pumping laser light spot.

Abstract: Broadband laser gain is obtained in semiconductor materials by pumping an ultra-short laser cavity with picosecond excitation pulses. The broadband laser gain is used to provide picosecond laser radiation energy covering a wide spectrum of frequencies.

Abstract: A magneto-optic modulator of the bounce-cavity type is disclosed wherein the mirrors that are attached to the garnet crystal to provide the reflections are multilayered dielectric mirrors. By polarizing the input beam such that its E vector is perpendicular to the plane of incidence substantially total reflection is achieved from the mirrors and all of the input beam emerges from the garnet crystal. A metal film deposited on a plane of the crystal that is perpendicular to the mirrors permits the establishment of a magnetic field that is substantially parallel to the reflected beams within the crystal. When the field is established by passing current through the film, much of the light is lost during each of the reflections since substantial amounts of the polarized light having polarizations in the plane of incidence are coupled through the dielectric mirrors. Hence the intensity of the output beam is modulated by the current in the metal film.

Abstract: There is disclosed a technique for growing, from a melt, doped single-crystal fibers for use as lasers or other active or passive optical devices of a size that is compatible with proposed optical fiber communications systems. A rod of undoped material has deposited thereon, by mechanical means, a powder or a slurry of a compound of the active ion or other dopant. A melt is formed at the end of the rod with a laser beam and a reduced diameter doped single-crystal fiber is grown or drawn from the melt by pulling with a wire or, when desired crystalline orientation is needed, by pulling with a pointed and oriented seed crystal. The pulling step, at least in the specific case of a neodymium-doped yttrium aluminum garnet (YAG) fiber, is repeated a plurality of times with approximately a 3:1 diameter reduction each time in order to obtain the desired fiber size; but only one deposition of the dopant compound is needed.