Abstract: The invention provides a method for controlling the transmission of radiant energy through a light transmissive medium and an apparatus whereby the method can be effected.

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: 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: A bistable optical device integrated onto a semiconductor chip with a photoresponsive element receiving an input light signal and connected electrically to a photo emitting element so that the reverse current produced in the photoresponsive element by the input light signal causes light emission which is incident upon the photoresponsive element to increase reverse current by positive feedback, resulting in change from a low to high light output at a first change value of input light and a high to low output at a second and lower change value. A light modulator is formed between the elements to receive an input light signal and vary the amount of light received by the photoresponsive element from the photo emitting device and hence the change values.

Abstract: An optical bistable device comprising a semiconductor laser including a diffraction grating which diffracts light parallel to the grating for laser resonance and additionally diffracts a higher order Bragg beam perpendicular to the grating. An optical detector receives the higher order beam and produces an electrical signal which is used as a partial exciting current for the semiconductor laser. Thereby, the two optical ports of the laser can be used for other purposes.

Abstract: A semiconductor laser for use as a bistable optical device in which an active semiconductor layer has corrugations of predetermined pitch on its surface and a semiconductor optical waveguide is formed on the corrugation. At least one end of the active layer is exposed at an oblique angle so that light in the active layer propagating along the direction of corrugation is reflected from the oblique face to a normal of the surface of the laser. Electrodes are provided above and below the active layer.

Abstract: Integrated laser diode devices are utilized as repeater elements and logic circuit elements in fiber optic and other light transfer systems. One embodiment discloses a six layer device (10) which is triggered not by an external electrical gating source, but by an external light source (8, 9) as from an optical fiber. Another embodiment operates a laser diode in a bilateral mode. That is, depending on the polarity of the applied voltage bias V to the device (50), two separate light pulses are emitted from different regions (56, 52) of the crystal. A further embodiment utilizes the semiconductor laser as a logical AND function. When the electrical bias (V) of the device (60) is set so that when at least two external light sources (67, 68) are applied, the device will emit laser light (69). Still another embodiment utilizes two semiconductor laser devices (911, 913) as an astable optical multivibrator (90).

Abstract: Drive current for a light emitting semiconductor device, such as an injection laser, is supplied by a digitally programmable current source capable of supplying any one of a plurality of different discrete current amplitudes. Light emitted by the device is sensed and an amplitude parameter (e.g. instantaneous current or power amplitude, average current or power amplitude, modulation amplitude, etc.) is digitally encoded. A logic circuit responsive to the digitally encoded amplitude parameter and optionally responsive to other digital signals as well, controls the discrete current amplitude supplied by the programmable current source.

Abstract: Integrated laser diode devices are utilized as repeater elements and logic circuit elements in fiber optic and other light transfer systems. One embodiment discloses a six layer device (10) which is triggered not by an external electrical gating source, but by an external light source (8, 9) as from an optical fiber. Another embodiment operates a laser diode in a bilateral mode. That is, depending on the polarity of the applied voltage bias V to the device (50), two separate light pulses are emitted from different regions (56, 52) of the crystal. A further embodiment utilizes the semiconductor laser as a logical AND function. When the electrical bias (V) of the device (60) is set so that when at least two external light sources (67, 68) are applied, the device will emit laser light (69). Still another embodiment utilizes two semiconductor laser devices (911, 913) as an astable optical multivibrator (90).

Abstract: A laser functional device formed by photoelectric direct loop coupling of a laser diode and a photodetector, the latter of which receives a part of an output light of the former together with an external input light and excites the former by an output current thereof, can be easily miniaturized and integrated as a fundamental function active device self-containing a light source and presenting various useful functions of the optoelectronic technology between the external input and the output lights.

Abstract: Bistable optical device comprising two lasers. The light beam which can be emitted by one of the lasers passes through the amplifying medium of the other and vice versa. According to the invention the lasers are of the semiconductor type and the resonators of the two lasers are tuned to two different wavelengths, the directions of these two beams coinciding.

Abstract: An optical modulator is provided in which one light beam is modulated by another. The modulator of the invention includes a saturable medium which is capable of amplifying an optical signal by stimulated emission of radiation. Two optical signals, in the form of two light beams are caused to pass through the medium and to emerge from the medium in amplified form. The beams, however, are caused to have different gains in the medium either by causing the beams to have different path lengths, or by other means. The beams are intercoupled by cross-saturation of the medium. Thus, any variations in the intensity of one of the beams causes a change in intensity in the other beam. Since one of the beams has a greater gain than the other, a small change in the intensity of one of the beams will produce a large change in the intensity of the other beam, thus producing in many aspects the optical analog of the transistor. The modulator of the invention shall be referred to herein as an "opto-optic" modulator.