Abstract: An optically controlled semiconductor waveguide interferometer apparatus includes a Mach-Zehnder interferometer formed of semiconductor laser materials. A first optoelectronic switching means is adapted to be coupled across a first voltage potential and one of the optical paths of the interferometer. The first optoelectronic switching means has a first gap therein. Likewise, a second optoelectronic switching means is adapted to be coupled across a second voltage potential and the other of the optical paths. The second optoelectronic switching means has a respective gap therein. Light pulses are applied to the two gaps for controlling the index of refraction of the optical paths, whereby the light pulses control the interferometer so that the output intensity of the interferometer is modulated.

Abstract: A process for thinning fruitlets or fruits by exposing the crops to far-red night-break lighting treatments at certain stages of flower and fruit growth and development.

Abstract: A method of inhibiting premature budding and subsequent flowering of a floral crop selected from the group of chrysanthemum and poinsettia during the season in which the daily photoperiod does not exceed ten hours comprises the step of illuminating the crop, generally six hours after the onset of a night period, with a fifteen minute illumination of a narrowband red light having a predominant emission peak centered around 660 nm having an intensity in the range of 1 .mu.W/cm.sup.2 to 50 .mu.W/cm.sup.2.

Abstract: The duration of a very short semiconductor laser pulse, such as that ranging from a fraction to hundreds to picoseconds, can be measured utilizing the internally generated second harmonic emission of the laser. A laser diode is driven so that light emitted therefrom can pass through a beam splitter and be reflected by the beam-splitter into a photomultiplier and into a detector, respectively. Signals received therefrom relate to the conversion efficiency of the second harmonic emission generated by the picosecond pulses and of either continuous wave emission or pulse emission whose durations can be accurately measured by photodetectors. Apparatus includes a photodiode for measuring the fundamental laser power, a photomultiplier for measuring the second harmonic power, and appropriate filters. Ammeters coupled to the photodiode and photomultiplier measure the appropriate current. The ratio of the current can be determined by a ratio circuit or a computer.

Abstract: An achromatic birefringent retardation plate has a quarter wave of linear optical birefringence over a wavelength range centered about a nominal wavelength. The plate includes a combination of two birefringent optical disks in adjacent positions along a light beam axis. Each disk has a linear optical birefringence with a fast axis. The two disks have thicknesses such that, at the nominal wavelength, they have their linear optical birefringence at n and m quarter waves, respectively of the nominal wavelength, where n is an odd integer greater than one and where m is an even integer greater than n. The fast axes of the linear birefrigences of the disks have rotational orientations about the light beam axis whereby the fast axis orientation of the other disk differs from that of one disk by ninety degrees, plus or minus one-half of the angle whose cosine is equal to the ratio of n to m.

Abstract: Devices for efficiently coupling electromagnetic radiation in the far infrared and sub-millimeter microwave regions of the electromagnetic spectrum to surface electromagnetic waves comprise a material of negative dielectric constant having a grating contoured surface overcoated with a transparent organopolymeric material. The efficiency of coupling between the free radiation and the surface electromagnetic waves can be optimized by adjusting the thickness of the overcoating layer.

Abstract: Methods of and apparatus for measuring the frequency response of optical detectors based on interferometrically demodulating a frequency modulated semiconductor laser. Detectors can be characterized where the 3 dB roll-off frequency is in excess of 100 GHz, is self-calibrating by simplified and inexpensive techniques.

Abstract: A sequential configuration of log.sub.2 n stages of birefringent elements are set forth. Each stage has a transfer function approximating a square wave, and successive stages have half periods. An input beam with n wavelength components would be demultiplexed into 2, 4 and finally n output beams at the output of the first, second, and log.sub.2 n stages, each output beam containing only one wavelength. Successive stages consist of two polarizing beam splitters between which is located their appropriate length of birefringent element to achieve the desired transfer function.

Abstract: Frequency modulated light is provided to an optical fiber by exciting a laser medium, such as a diode laser, so that stimulated emitted radiation, at a fixed wavelength .lambda., emanates from opposite surfaces of the medium. One end of the fiber is coupled to one of the surfaces. A reflecting medium is provided a distance (n.lambda.)/4 away from the other of the surfaces (n being a positive integer) to reflect emanated radiation from the other surface back to the other surface. The reflecting medium is oscillated in accordance with a signal to be modulated. The radiation reflected back to the other surface tends to cancel or reinforce, respectively, the radiation that emanates from the one surface, when n is an odd integer or an even integer, respectively. The reflecting medium can be a light reflecting diaphragm adapted to be acoustically oscillated.

Abstract: An n channel birefringent multiplexer/demultiplexer consists of log.sub.2 n sequences of birefringent crystal elements in Solc-type filter configuration. The configuration of polarizing beam splitters have one such beam splitter before the first sequence, one such beam splitter after the last sequence, and solely one such beam splitter between adjacent sequences of birefringent elements. With such multiplexer/demultiplexer horizontally and vertically polarized components of an input beam are separated at the input beam splitter, independently traverse all of the sequences of the birefringent elements and are recombined to form output beams only upon reaching the output beam splitter.

Abstract: A teleconferencing bridge simulates the auditory spatial ambience of a face-to-face conference. This bridge uses a novel binaural approach to simulate spatial ambience.

Abstract: A monolithic external-coupled-diode laser structure uses high reflectivity facet coatings to reduce the operating current and to improve suppression of unwanted longitudinal modes.

Abstract: A process for accelerating dehiscence and reduction in "pull force" of fruits and nuts (in order to facilitate the mechanical harvesting process) by exposing the crops to far-red night-break lighting treatments at certain stages of fruit growth and development.

Abstract: Mechanical translation tips can be attached to a fiber version of a frequency chirped interferometric displacement sensor. The mechanical tips can be used in noisy or deleterious environments that preclude the use of non-contact optical sensors. These tips can also be used with a hydraulic amplifier to increase the resolution of the sensor to less than one micron.

Abstract: A multipulse starting aid for a high-intensity discharge lamp includes a spiral line, a bi-directional solid-state switch, or a spark gap, coupled to one of the ends of the spiral line, a resistance in association with the spiral line to provide an RC time constant. The time constant RC is so adjusted that, upon receiving the alternating current voltage from the appropriate source, a waveform of voltage is presented across the pair of terminals of the lamp, together with the series of pulses at the peak of each half cycle of the waveform. thereby enhancing the lamp startability.

Abstract: A re-entrant, low-pressure, electrodeless lamp apparatus includes two identical re-entrant center conductors driven in quadrature, resulting in a matched lamp input impedance in both the off and on states nearly independent of incident microwave power.

Abstract: A clocking pulse generator includes means for receiving voltage from a multi-phase alternating current electrical power source. A vector summing circuit provides a non-zero resultant vector for various combinations of multi-phase operating conditions. A multi-phase voltage dividing circuit couples the receiving means to the vector summing circuit. The non-zero resultant vector is converted into a halfwave rectified signal and applied to a first input of a comparator. The second input of the comparator is coupled to receive a preset threshold voltage. The comparator generates an output which provide clocking pulses therefrom.

Abstract: A high power single spatial mode semiconductor laser provides strong lateral index guiding to maintain single transverse mode output and yet has a large cavity area. The large cavity area provides low series resistance, low thermal resistance, and lower operating current densities and photon densities than can be achieved by conventional cavity designs. The result is a laser which can operate at high output power at a single transverse mode. In the plane of the p-n junction, the active layer has a cross-section including a waveguide section of width between 1-2 microns which provides lateral mode stability and discrimination against high order transverse modes with a directly adjacent amplifier section consisting of a layer of about 5-20 microns width and several hundred microns in length. Due to the large cross section area of the amplifier section, the majority of the current flows through the amplifier section where most of the heat is generated.

Abstract: A complete set of optical logic gates and circuits based upon direct polarization switching, and various types of optical flip-flops based upon polarization bistability, in semiconductor lasers are described. By operating the laser in the direct polarization switchable mode, logic gates and circuits such as inverter, AND, NAND, OR and NOR can be provided with two optoelectronic switches or photodetectors. With the laser being operated in the polarization bistable mode, clocked optical flip-flops are operable with a few optoelectronic switches or photodetectors.

Abstract: A chirped grating focuses guided waves to variable space points as determined by the intensity of a control beam. This can be achieved with a light controlled spatial scanner which includes a corrugated waveguide fabricated of a material having a non-linear index coefficient of refraction n.sub.2. The waveguide has corrugations with a period that varies linearly from .LAMBDA.(O) at one point to .LAMBDA.(L) at another point, where .LAMBDA.(O) is greater than .LAMBDA.(L). Guided modes of light are applied within the waveguide in a direction from the one point to the other point wherein the corrugations couple light from the guided modes to radiation modes focused at a focal spot in space. The intensity of the light within the waveguide is varied to cause the focal spot to traverse a path without the waveguide, dependent upon the varied intensity.