Abstract: A birefringent optical wavelength multiplexer/demultiplexer includes a first polarization beam-splitter, a first reflector, a plurality of birefringent elements, a second reflector, and a second polarization beam-splitter. The plurality of birefringent elements are so oriented that each element introduces an additional sinusoidal component to the transfer function of the device that tends to effectuate a flattened transfer function.

Abstract: An adjustable waveguide short circuit using a thin partition or rectangular pin parallel to the E-field in the waveguide and movable along longitudinal slots centrally located on the two broad walls of the waveguide.

Abstract: An optical square wave multivibrator includes a semiconductor laser that operates near the polarization transition temperature in a pure TM mode at low injection currents and switches operation to a pure TE mode at high injection currents, and vice versa. Near such temperature, the semiconductor laser experiences large hysteresis loops with high contrast ratio in its polarization-resolved power vs current characteristic while total power exhibits only slight change in hysteresis. The switching behavior of the TE mode is complementary to that of the TM mode. The laser is biased within the hysteresis loops. A current pulse applied in one direction to the laser causes it to provide a TE mode laser output, whereas a current pulse applied in the other direction causes the laser to provide a TM mode laser output.

Abstract: The simultaneous and equal tuning of two birefringent crystal elements of a Solc type optical filter by pairs of quarter-wave plates adjacent to each and oriented such that equal and opposite physical rotations between the plates of each pair tunes its adjacent birefringent element in the same direction without changing the relative orientations of the filter input and output. Also, the simultaneous and equal tuning of two birefringent crystal elements of a Solc type optical filter by the rotation of a single contiguous group of optical components.

Abstract: In conventional InGaAsP/InP semiconductor lasers the p-doping in the InP laser level cannot be increased above 1.times.10.sup.18 atoms/cm.sup.3 without adversely affecting the optical characteristics of the devices. However, by introducing a thin low-doped p-InP layer and a thicker highly doped InP layer, good optical characteristics can be maintained and series resistance can be reduced by a factor of 2 to 4, thereby resulting in operable devices having significantly increased operating currents and higher output power than those of the prior art.

Abstract: An improved geometry for an optical beam splitter prism permits all input and output beams to be parallel and to remain parallel while the prism is misaligned. It is particularly useful in conjunction with fiber optic couplers and is applicable to splitting with respect to light intensity, polarization or wavelength. This can be achieved through the construction of a beam splitting prism having an additional reflecting surface on one input beam and on one output beam, whereby each of these surfaces are parallel to the beam splitting surface and with two parallel input and output surfaces through which all beams pass so as to make all input and output beams parallel and remain parallel as the prism is translationally or rotationally misaligned about any axis.

Abstract: Apparatus for evaporating numerous layers of various substances upon a substrate includes square witness chips transparent to a specific beam of radiation. A witness chip holder, having a cylindrical base, has an axial hole vertically disposed from its central axis. The axial hole has a cross-sectional shape that corresponds to the external configuration of an octagram wherein recesses of right-angled vertices of the octagram are formed in the axial hole. Each witness chip is rotatably stacked within alternate formed verticular recesses of the octagrammatic hole. A drum with a square hole at its base has a cylindrical recess for receiving the cylindrical base of the witness chip holder, thus providing for reciprocating movement therebetween. The square hole is slightly larger than the witness chip so that the lowermost witness chip of a stack of chips is held at its vertices by the base of the drum.

Abstract: A centering device holds an optical fiber along an axis with three fiber receiving sections and a receiving member. The receiving member has a concentric cylindrical cavity for holding assembled sections. Each section, substantially identical, has a uniform cross-sectional configuration at right angles along a major portion of its length forming a boundary of fixed perimeter. One portion of one section contacts another section. Another portion contacts a different section. A third portion contiguous to the first two portions is adapted to engage an optical fiber along its length. A fourth portion contiguous to the first two, but not to the third, engages the cylindrical wall defined by the concentric cavity. The cavity terminates with a planar wall perpendicular to the axis. It can have an axially oriented truncated conical recess. The fourth portion of the boundary engages differing amounts of a cylindrical wall depending upon the shape of the fourth portion.

Abstract: Apparatus couples optical fiber to an optoelectronic component with a collet, a cylindrical member, a connector, and hermetically sealing means. The collet has a central orifice through a knurled end portion, a central portion with a male thread, and a second end portion formed with a slotted cone sleeve. The cylindrical member has opposed centrosymmetric recesses that meet, forming a small axially oriented aperture. One recess is formed with an axial female thread, with a conical indentation terminating at the aperture. The female thread can to engage with the collet male thread. Thread engagement of member and collet results in engagement of the member at the conical indentation with the coned sleeve, drawing the slotted sides inwardly, firmly gripping the collet held optical fiber. The other recess has a second axial female thread from the opposite end of the member toward the aperture. The member has a radially directed sight hole.

Abstract: A high speed laser driver includes a differential pair of bipolar transistors sharing a common emitter resistor as in the prior art. However, an improvement thereover resides in the use of Schottky barrier diodes, one of which couples the emitter of one transistor to the common emitter resistor and the other of which couples the emitter of the other transistor to the common emitter resistor. Furthermore, separate resistors couple the emitters of both transistors to a voltage source so that the transistors are always conducting.

Abstract: A high speed laser driver includes a differential pair of bipolar transistors sharing a common emitter resistor as in the prior art. However, an improvement thereover resides in the use of Schottky barrier diodes, one of which couples the emitter of one transistor to the common emitter resistor and the other of which couples the emitter of the other transistor to the common emitter resistor. Furthermore, separate resistors couple the emitters of both transistors to a voltage source so that the transistors are always conducting.A high speed logic circuit includes a pair of input bipolar transistors, and a reference transistor, sharing a common emitter resistor as in the prior art. However, an important resides thereover in the use of Schottky barrier diodes that couple the emitters of the transistors to the common emitter resistor. Furthermore, separate resistors couple the emitters of the three transistors to a voltage source so that the transistors are always conducting.

Abstract: A fluidic support device is described that counteracts the gravitational bending moment present in a substrate tube during a modified chemical vapor deposition preform fabrication process. Hence, use of this device results in the production of a straight optical fiber preform. The device includes a hemicylindrical annulus section in close proximity to the portion of the substrate tube to be supported, and uses flowing fluid to offset gravity and to center the substrate tube. Gaseous use of the device increases and stabilizes the thermophoretic force without contact by either solid or liquid materials, avoiding any reduction in strength of the finished fiber.

Abstract: A multiple port electromechanical optical fiber switch provides for the exchange redirection of one common optical path with one of several other optical paths through the switch. It is particularly useful when one standby laser transmitter must be quickly substituted for any single failed transmitter among a group of several actively operating transmitters. A prism for exchanging the optical paths of two initially parallel beams by means of four refractions at their entry and exit points and at least two internal reflections per beam within the prism is set forth in modified rhombic form with two additional parallel facets that transmit undeflected in the deactivated position one of two beams so as to minimize required shift distance to the prism activated position where it exchanges the optical paths of both parallel beams.

Abstract: A fluidic support device is described that counteracts the gravitational bending moment present in a substrate tube during a modified chemical vapor deposition preform fabrication process. Hence, use of this device results in the production of a straight optical fiber preform. The device includes a hemicylindrical annulus section in close proximity to the portion of the substrate tube to be supported, and uses flowing fluid to offset gravity and to center the substrate tube. Gaseous use of the device increases and stabilizes the thermophoretic force without contact by either solid or liquid materials, avoiding any reduction in strength of the finished fiber.

Abstract: An optical fiber can be coupled to a semiconductor light source or detector using molded lens elements. The apparatus is easy to assemble, it is inexpensive, and it achieves true hermetic sealing of the semiconductor for a good reliability.

Abstract: A predistortion circuit that cancels second order distortion of light emitting diodes enabling interference free transmission of multiple vestigial sideband television channels through a single optical fiber. This is achieved by preamplifying a signal with an amplifier that has opposite characteristics to the distortions of a light emitting diode.

Abstract: An enhanced mobility buried channel transistor structure in which the quasi-two-dimensional electron gas (2DEG) which forms the conducting channel in the structure is removed from the proximity of the heterointerface, and is placed in a region remote therefrom. A "tapered" layer of Al.sub.x Ga.sub.1-x As is provided, where x varies from maximum to minimum as the interface with an undoped layer of GaAs is approached.

Abstract: An active system for restoring the polarization state of light emerging from a single-mode optical fiber. The system changes the slowly varying elliptical polarization resulting from environmental effects on the long fiber to a linear polarization state of fixed orientation. The elliptically polarized light is converted into two orthogonal linearly polarized beams. One of the beams is used in a feedback circuit to null its intensity thereby restoring all the input light to the other linear polarization state.

Abstract: A laser device with a discharge tube forming a closed envelope with cylindrical end portions connected by an elongated constricted center portion and having external electrodes at the end portions, fed from a source of short pulses with a width measured in nanoseconds, capacity coupled to the discharge plasma. The discharge plasma may include metal vapor, a metal halide, including mercury halide, and internal electrodes may be included in the closed envelope but coupled to the external electrodes by capacity coupling so as to avoid any connections from electrodes passing through the glass or fused silica envelope.

Abstract: An electro-mechanical optical fiber rotary switch provides for latched reconnection of two optical paths among four optical fiber ports of a 2.times.2 switching array. A right isosceles triangular optical prism is used in the switch, the prism being rotated 90.degree. in either direction to change the switch position.