Abstract: The present invention detects prelasing in a Q-switch laser and terminates laser operation upon such detection. A detector senses the presence of light beyond a Q-switch and generates an appropriate electrical signal. A comparison stage circuit compares this detector signal with an established threshold value indicative of prelasing and generates a trigger signal if this detector signal exceeds this threshold value. A control stage circuit receives both this trigger value and a sampled Q-switch signal indicative of an opening of the Q-switch. The control stage circuit terminates operation of the laser if the trigger signal from the comparison stage is received while the sampled Q-switch signal is being received to avoid the effects of prelasing. Appropriate delays and timing sequences are established.

Abstract: The advantages of both active and passive modelocking techniques are realized within a single device by providing a p-i-n modulator formed at antiresonance within a Fabry-Perot etalon. The p-i-n modulator actively modulates light within the laser cavity by introducing periodic loss in response to changing voltages applied to the modulator. The p-i-n modulator includes an intrinsic region that is disposed between a p-doped region and an n-doped region. The modelocking performance of the p-i-n modulator is enhanced by the saturable absorber action of the intrinsic region.

Abstract: A laser system having a laser rod, flash lamp, and a Q-switch including an electro-optical cell, is operated to provide double laser output pulses closely spaced from each other, e.g., within 5 microseconds. Two Q-switch drivers are provided with independent high voltage power supplies which can provide different high voltages to the two Q-switches. The outputs of the Q-switches are provided to an interface circuit which includes back-to-back diodes connected to a node which is connected to the output provided to the electro-optical cell. A control signal is provided to the first Q-switch driver after the flash lamp has been fired to provide a first pulse to the electro-optical cell to provide a pulse of light from the laser. A selected period of time thereafter, a control signal is provided to the second Q-switch driver to provide an output pulse through the interface circuit to the electro-optical cell to provide the second light pulse from the laser.

Abstract: An injection seeded, single frequency ring laser source is presented wherein stabilization and single frequency control is accomplished by measuring the intensity or power of the portion of the high power laser beam generated in the ring slave laser and which is directed to return to the seed laser. When the intensity of the return beam falls below a preset threshold level, the in-phase operation of the laser system has been established and high energy single frequency pulses are generated and emitted.

Abstract: A laser gyro having a laser source for providing laser energy includes a laser gain device for receiving lasing energy and generating first and second counterpropagating laser pulses along a common optical path. A detector detects at least one of the pulses and generates an index of refraction control signal representative of the detected at least one laser pulse. The index of refraction of a segment of the optical path is varied in response to the index of refraction control signal such that the index of refraction of the segment of the optical path changes an optical path length for one of the laser pulses. A detector senses the beatnote between the first and second counterpropagating laser pulses.

Abstract: Disclosed is an optical waveguide recording medium playing apparatus which has a heterodyne detection optical system and uses a waveguide light delaying/reflecting device for a reference light generating optical system. This waveguide light delaying/reflecting device is provided with a transducer which is disposed in close proximity of an optical waveguide where light is guided and which generates a surface elastic wave, so that the surface elastic wave may propagate in the light propagating direction of the optical waveguide. A laser beam is guided on the otpical waveguide, and a high-frequency drive current modulated in a burst form is applied to an electrode to generate a surface elastic wave, thereby accomplishing the shifting and phase delay of the light frequency of the reference light which ensures information reproduction with the interaction with the laser beam and the surface elastic wave. This optical waveguide is formed by diffusing Ti, Rb or the like on a substrate of GaAs, SiO.sub.2, or TeO.sub.

Abstract: An integrated semiconductor device which forms an optoelectronic switch and includes: a directional coupler structure in which one of the guides receives the input light power and the other guide is formed by multiple quantum wells, which structure is so dimensioned that in the zero-bias state the switch is in the crossover state, and switching control means.The structure includes layers which form at least one PIN structure in which the waveguide consisting of multiple quantum wells constitutes an intrinsic region I, and the control means include means for reverse-biasing of the PIN structure which supplies the negative feedback so that switching from one state to the other is initiated by a change in the level of the luminous power injected into the input waveguide.

Abstract: A device for damping the vibrations of an elongated, substantially rectangular crystal in response to an applied high voltage electrical field comprises a pair of dielectric panes which are impedance matched with the crystal and are attached to opposite sides thereof. As attached to the crystal, each of the panes is disposed at the periphery of the electrical field, and an aluminum block is attached to each of the panes on a surface which is opposite from the crystal. The mass of aluminum blocks, and the texture of their exposed outer surfaces cooperate to mechanically dampen the acoustic vibrations transmitted from the crystal through the panes. Additionally, the rectangular dimensions of the crystal are chosen to delay the propagation of acoustic waves from the surfaces of the crystal to its center.

Abstract: This invention discloses a method and apparatus for shortening the length of a pulse of light. Generally, the method entails altering the index of refraction of an optical medium (14) through which the pulse of light is traveling at an area of the medium (14) where the front end of the pulse of light is located, such that the front end of the pulse of light travels slower than the back end, thus enabling the back end to catch up with the front end in order to shorten the length of the pulse. To accomplish this, it is proposed to generate an electric field across the optical medium (14) by a charge carrying medium (12) positioned relative to the optical medium (14), such that the index of refraction is altered by the electro-optic effect.

Abstract: A laser system is provided with a multi-function intra-resonator loss modulator to generate laser output having selectable amplitude within a relatively wide amplitude range and selectable duration within a relatively wide duration range while preserving mode quality, waist position, and divergence of the laser output.

Abstract: A tunable, single-frequency, solid-state ring laser includes a solid-state laser material pumped by laser-diode light and at least one additional external piece which reflects the intra-cavity lasing light in a closed loop such that the plane of polarization is changed in an appropriate amount to compensate for magneto-optic change (Faraday rotation) of the plane of polarization, which occurs either inside the solid-state material or in one of the external pieces which traversed by the intra-cavity lasing beam. At least one of the external elements has the ability to change the optical path length of the intra-cavity lasing beam in order to tune the laser frequency by means of mechanical movement, electro-optic properties, magneto-optic properties, or some combination of the above properties.

Abstract: A method and apparatus is presented whereby control of the frequency of pulses emitted by a resonant ring slave laser is forced to a single frequency defined by a seed laser through the control of the pathlength of the ring laser resonant path. By monitoring the time difference between turn on of a Q-switch within the laser resonant cavity and the time of occurrence of the output pulse of the slave laser, and effecting changes to the ring laser resonant path in a manner to minimize the measured time difference, the frequency of the output pulse from the slave laser is driven to a single frequency defined by the seed laser resonator.

Abstract: Disclosed is a laser pulse generator in which a single pulse is generated from a train of pulses. The amplitude of this single pulse is the addition of the amplitudes of the pulses of the train of pulses. This addition is done in a non-linear crystal inserted in an optical loop. The train of pulses takes the place of a pump wave applied to the non-linear crystal and the signal circulating in the optical loop takes the place of a signal wave. This signal wave therefore benefits from a transfer of energy coming from the pump wave because of the interaction in the non-linear crystal.

Abstract: A laser system wherein a pulsed switching signal is applied to the modulator to provide a mode-coupled output beam having spaced short pulses. The synchronized pulsed switching signal can be provided by an external driver and or by feedback from the laser beam.

Abstract: An electro-optic modulator (10) includes a pair of optical waveguide channels (20, 22) formed in an X-cut lithium niobate substrate (12) and an overlying RF coplanar waveguide (36). A periodic electrode structure (48) of the intermittent interaction type employs a plurality of middle stubs (52) to maintain the phase of the RF drive frequency in phase with the optical signal. The modulator (10) also utilizes shorter stubs (64) and tapered inlets (42) and outlets (44) to match and transform impedances.

Abstract: A Q-switch for a laser having a resonant cavity including an output coupler, a gain medium and a retro-reflecting mirror is mounted in the resonant cavity between the gain medium and the retro-reflecting mirror. The Q-switch comprises a polarizer and a phase retarding element (such as a Pockels cell) which includes a birefringent substrate for inducing a controllable phase retardation in the cavity mode in response to an applied electric field. A tiltable mount supports the phase retarding element so that the lasing axis lies essentially in a plane of the crystallographic axis 45.degree. from the direction of polarization, and lies at an adjustable angle relative to the crystallographic axis. A control circuit supplies an applied electric field within the substrate having a first magnitude in a first state and a second magnitude in a seocnd state. In the first state, the phase retarding element induces 90.degree. rotation in a round trip for the cavity mode.

Abstract: There is provided by this invention a controller for cavity dumping a laser which maintains a consistent output pulse energy level. The constant output pulse energy level is due to the clipping of the circulating power within the laser's cavity upon its reaching a threshold level. In order to further insure that the output pulses are of equal energy even within a laser that is pulse interval modulated, the threshold level for the circulating power within the laser's cavity is adjusted according to a predetermined ratio of the number of times the circulating power is clipped to the number of times the circulating power is not clipped so that the predetermined ratio is maintained.

Abstract: A room-temperature, laser-pumped, Q-switched, thulium-doped, solid state laser for producing pulses of laser emission at substantially 2 microns is disclosed. In a preferred embodiment, the laser comprises: a laser cavity defined by first and second reflective elements opposing each other on a common axis to form a reflective path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material doped with an amount of thulium activator ions sufficient to produce a laser emission at substantially 2 microns from the .sup.3 F.sub.4 to .sup.3 H.sub.

Abstract: The invention is directed to a laser arrangement for converting frequency wherein the fundamental frequency or the converted frequency can be selectively emitted by means of an optical element which can be pivoted into and out of the beam path. An especially slim configuration of the overall arrangement is obtained with the aid of an additional deflection element.

Abstract: A microwave oscillator frequency modulates the output of the laser system to be controlled. The modulated output passes through a molecular gas cell. The output of the molecular gas cell is detected by a square law device, which produces a signal at the desired microwave frequency only when a sideband of the modulated laser output coincides with the desired molecular transition frequency. A quadrature signal pair is produced by mixing the filtered output of the square law device with two phase-shifted signals from the microwave oscillator. The dispersion signal can be used to control the output frequency of the laser system, since its magnitude and sign are uniquely related to the required direction of correction.

Abstract: A high-speed broadband tunable laser system is disclosed. In one illustrated embodiment, a microprocessor-controlled synchronous tunable laser system is disclosed having multiple tuning elements. The tuning elements can be individual birefringent crystals (such as potassium deuterated hydrogen phosphate) which exhibit electro-optic effects when electric field is applied. Two (or more) of such elements provide coarse and progressively finer control over the wavelength and linewidth. The appropriate voltage values for each element can be stored in a random access memory within a controller and retrieved immediately to obtain a desired wavelength within milliseconds without the scanning delays inherent in mechanical systems.

Abstract: A laser light source with reduced sensitivity to optical feedback effects comprises an emitter device for emitting laser light. A body of electro-optic material is optically coupled to the emitter device for receiving and propagating light emitted by the emitter device. A time-varying electric field is established in the body of electro-optic material. Consequently, the frequency of the light emitted by the laser diode is shifted when it propagates through the body of electro-optic material.

Abstract: An optical modulator comprises a crystal (15) of material exhibiting the pyroelectric effect, and charge-dissipating means for dissipating any charge built up on the optical faces of the prism. The charge-dissipating means may comprise point electrodes (30) positioned adjacent to the optical faces (21) of the crystal and connected to an alternating-current high-voltage power supply (31). The electrodes produce charged ions which neutralize any charge on the optical faces of the crystal. The crystal may be used as the Q-switch in a laser.

Abstract: A neodymium or other rare earth doped solid state laser is pumped by a matched high efficiency laser diode, including a diode array and a multi-spatial mode extended emitter diode, resulting in a compact, high efficiency and long lifetime laser assembly. The cavity mode volume is matched to a region of absorption in the pumping volume formed by the focused diode beam. Output is in the near infrared range, but can be converted to the visible spectrum by an intra-cavity frequency doubler. A doubling crystal, e.g., KTP, is placed in an optimum location in the laser cavity. Polarization of the beam for frequency doubling may be achieved by using a birefringent material for the rod or by stressing a non-birefringent rod. An amplitude noise suppression etalon may also be placed at an optimum position in the laser cavity. A folded cavity configuration produces a pair of beam waists in the cavity. Pulsed operation can be produced by means of a Q-switch.

Abstract: A laser resonator has a semitransparent outlet mirror and a first mirror, with an active element between the mirrors, all the elements arranged perpendicular to the optical axis of the resonator. A shutter is provided behind the first mirror and a second mirror is arranged behind the shutter, perpendicular to the optical axis of the resonator. The second mirror is fully reflective for radiation with stronger laser transition and the first mirror is fully reflective for radiation with weaker laser transition and fully penetrable for radiation with stronger transition. The resonator can change frequency simply by opening or closing the shutter. It can be advantageously used, for example, in the design and construction of laser scalpels.

Abstract: Higher efficiency in cavity dumping and frequency doubling in a laser used to produce modulated output beam pulses is achieved by deflecting light out of the resonant cavity to a third mirror through a frequency doubler using an electro-optic modulator and a polarizing beamsplitter in the resonant cavity, or using just an acousto-optic modulator to deflect light out of the laser cavity in response to a control signal (electric or acoustic). The frequency doubler in front of the third mirror rotates the frequency doubled light so that it will pass out of the laser cavity through the polarizing beamsplitter, while undoubled frequency light is reflected by the polarizing beamsplitter back into the gain medium of the laser. In the case of using a type-II frequency doubler, a dichroic beamsplitter deflects out the frequency doubled light and passes the undoubled frequency light to the polarizing beamsplitter for return to the laser gain medium.

Abstract: The present invention provides layered devices to control the spatial and spectral distribution of energy in optical beams, particularly high-intensity laser beams. These devices include improved versions of prior art thin-film (vacuum-deposited) interference filters, rugate structure anti-reflection coatings, Q-switches, pulse shapers, modulators, optical bistable devices and the like. Control is provided using materials with large second and third order susceptibilities to electric field polarization and, if necessary, means to apply appropriate electric fields.

Abstract: A multiwavelength laser source for providing a plurality of pulsed laser beams comprises a plurality of laser diodes optically connected with an oscillator to establish a beam of pulses of monochromatic light. A dispersion line for spreading wavelengths in each pulse optically connects the oscillator to a regenerative amplifier. An electro-optical crystal in the regenerative amplifier establishes the repetition rate of pulses in the laser beam and a pulse compressor is optically connected to the regenerative amplifier to establish the duration of each pulse. The laser source may also include a frequency doubler which is optically connected to the output of the pulse compressor to split the laser beam into components having different wavelengths.

Abstract: A circuit arrangement including a controllable optical resonator having a filter characteristic with a transmission peak arranged to pass laser radiation at a wavelength in the region of the transmission peak, wherein the resonator is positioned to receive the laser radiation at an angle such that two modes of the radiation, having respectively different polarization states, and wavelengths, are capable of propagating in the resonator. The resonator has control electrodes connected for receiving a voltage which determines the wavelength of the transmission peak of the filter characteristic and a source connected for applying to the electrodes a square-wave modulating voltage which varies between a first value which causes the transmission peak of the resonator to be substantially at the wavelength of one of the modes and a second value which causes the transmission peak of the resonator to be substantially at the wavelength of the other one of the modes.

Abstract: An optical crossbar switch employs the optical Kerr effect to cause switching of an input signal between two possible outputs. In the absence of a pump signal the output is on one fibre. In the presence of a pump signal the output is on the other fibre. The pump signal serves to produce rotation of the polarization of the input signal in a polarization maintaining coupler, the two possible polarization states being separated by a birefringent crystal or a polarization selective beam splitter.

Abstract: A neodymium or other rare earth doped solid state laser is pumped by a matched high efficiency laser diode, including a diode array and a multi-spatial mode extended emitter diode, resulting in a compact, high efficiency and long lifetime laser assembly. The cavity mode volume is matched to a region of absorption in the pumping volume formed by the focused diode beam. Output is in the near infrared range, but can be converted to the visible spectrum by an intra-cavity frequency doubler. A doubling crystal, e.g. KTP, is placed in an optimum location in the laser cavity. Polarization of the beam for frequency doubling may be achieved by using a birefringent material for the rod or by stressing a non-birefringent rod. An amplitude noise suppression etalon may also be placed at an optimum position in the laser cavity. A folded cavity configuration produces a pair of beam waists in the cavity. Pulsed operation can be produced by means of a Q-switch.

Abstract: A seeded electro-optically Q-switches laser includes a pulser for pulsing the Q-switch within the seeded laser. The Q-switch pulser includes a pulse-shaping network having a saturable core inductor connected in series with the flow of current to the Q-switch for causing the developed pulse voltage waveform in Q-switch to have an initially reduced rate of change to reduce unwanted Fourier frequency components of the seed optical radiation in the optical resonator of the slave laser, whereby enhanced single-mode operation of the slave laser is obtained with reduced seed power.

Abstract: A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume.

Abstract: Optical functions such as Q-switching, mode locking, cavity dumping, and modulation are generated by a simple laser arrangement which includes a gain medium and an electrically controllable, optical waveguide device optically coupled to the gain medium. The gain medium and waveguide device are either interposed between two reflective surfaces or coupled by a waveguide in order to form a single composite cavity laser structure.

Abstract: The invention relates to an electrooptical system mounted in a tunable laser cavity, made up of the association of passive and active birefringent components such as birefringent lenses (29) and electrooptical crystals (9), (10), (11) and (12) introducing a preset or adjustable optical-retardation as a function of the wavelength tuning range. The system is designed to be controlled by a small control voltage, and to tune the wavelength according to an arbitrary scanning law, with a tuning rate that can be high and with an adjustable emission line width.

Abstract: An optical fiber laser comprising a gain cavity in the form of a single mode optical fiber with integrally formed reflective end sections for provision of feedback. One end section is an etalon for modifying the gain cavity resonant characteristics and intensity modulation, and the other end section is used to alter gain cavity effective length to tune and frequency modulate. The emission spectrum of the laser gain material, which is preferably neodymium oxide incorporated in a silicate glass core, along with the etalon section reflection, pump energy level, and gain cavity length cooperate so that lasing takes place over just a single line of narrow width or over more than one line within a narrow band. Electro-optic material in the end sections permit output frequency and amplitude to be selectively activated in response to the application of applied voltages.

Abstract: The present invention provides a jitter stable electro-optical modulator for modulating a high power, repetitively pulsed laser having an optical risetime (10% to 90%) of the order of nanoseconds. The electro-optical modulator includes a birefringent electro-optical device; a hydrogen thyratron operated at a preselected high pressure and having an "ON" and an "OFF" state; first means responsive to the "ON" state of the thyratron for impressing a first preselected voltage across the birefringent electro-optical device; second means responsive to the "OFF" state of the hydrogen thyratron for impressing a second preselected voltage across the electro-optical modulator at a time coincident with the laser buildup interval; and means for repetitively driving the hydrogen thyratron into the "ON" and the "OFF" states repetitively at a preselected repetition rate.

Abstract: Optical functions such as Q-switching, mode locking, cavity dumping, and modulation are generated by a simple laser arrangement which includes a gain medium and an electrically controllable, optical waveguide device optically coupled to the gain medium. The gain medium and waveguide device are either interposed between two reflective surfaces or coupled by a waveguide in order to form a single composite cavity laser structure.

Abstract: A laser radar system employing a linear FM chirp laser followed by post detection pulse compression by a surface acoustic wave (SAW) device. The system includes an FM chirp modulator that provides the needed tuning range and linearity for pulse compression. This modulation is accomplished by using a high-pressure CO.sub.2 laser with an intracavity electro-optic modulator of CdTe. The frequency of the transmitter laser is accurately controlled through the application of high linearity, high frequency, sawtooth voltages to the two plates of the CdTe crystal, with the voltage waveform applied to one plate being out of phase with that applied to the other crystal plate. With the performance the system offers, absolute radar ranges can be measured to 0.22 m and velocities to 0.37 m/sec.

Abstract: A chirp laser system includes an intracavity electro-optical crystal modulated at a relatively high frequency, for example 250 kilohertz, to sweep the frequency of the transmitter laser above and below its nominal center frequency. One of the mirrors of the laser transmitter is adjustable to vary the length of the cavity and to shift the frequency of the transmitter laser. When the frequency of the transmitter laser is shifted, the output amplitude of the laser changes. With the center frequency of the laser at a maximum gain point, the amplitude of the output signals during positive and negative frequency excursions of the transmitter laser will be substantially symmetrical. However, if thermal or other effects cause the frequency of the laser to shift away from the maximum gain point, the output during positive and negative excursions will be asymmetrical.

Abstract: A laser comprises a laser medium and multiple resonators, together with means for switching coherent radiation from one resonator to another. If one of the resonators includes appropriate loss means, the laser can be self injection-locked and provide high-power, single-longitudinal mode radiation. Another embodiment of the laser provides successive laser pulses, separated by a short time interval and having different characteristics. A phase conjugate laser and an improved ring laser are also provided.

Abstract: Passive ring resonator laser gyro in which the clockwise and counterclockwise beams do not coexist in the resonator. The laser gyro employs thin film technology. In particular, the preferred laser is a gallium aluminum arsenide laser. Light from the laser is phase-modulated by means of a thin film electro-optic modulator comprising a channel waveguide disposed on an electrically active material and flanked by electrodes for modulating the phase of light from the laser. An electro-optic switch is provided for switching light from the laser to inject alternatingly clockwise and counterclockwise beams into the resonator. The resulting gyro is extremely compact and simply implemented into an integrated, thin film package. Because the clockwise and counterclockwise beams do not coexist in the resonator, various beam interaction effects such as beats, backscatter and feedback into the laser are eliminated.

Abstract: A laser amplifier buffer arrangement for selectively switching laser energy in a double pass laser amplifier. The buffer arrangement comprises a wedge of birefringent material which angularly separates incident laser energy into polarized components, and an electro-optic polarization switch which may be selectively controlled to circularly polarize the polarization components of light passing therethrough. A plane mirror is employed to reflect the polarized components back through the switch and wedge. The wedge and switch are aligned in a manner such that an arbitrarily polarized input beam is separated into two orthogonally polarizated components that traverse separate paths through the buffer. The polarized components are reflected back through the switch and wedge by the mirror which is aligned with the normal bisecting the polarization component separation angle.

Abstract: The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

Abstract: Laser apparatus with an electro-optic Q-switch assembly comprises a lasing medium which produces an unpolarized light beam when pumped, a polarizing beam splitter dividing the unpolarized beam into two orthogonally polarized parallel sub-beams, and a totally reflecting turning element which returns each sub-beam to the beam splitter along the path of the other sub-beam. A Q-switch is located in the path of one of the sub-beams. When the Q-switch is energized, the reflected polarization-shifted sub-beams are recombined at the splitter and pass through the lasing medium and adjacent partially-reflecting element as the output. When the Q-switch is deenergized, the sub-beams are dumped at the splitter which prevents the laser from oscillating.

Abstract: The invention deals with a face pumped slab laser in which the slab is of a rectangular configuration, favoring use of an optical resonator cavity capable of producing a rectangular beam of good quality within the cavity. The novel optical resonator cavity, which produces this rectangular beam, is stable on one axis corresponding to the smaller beam dimension and unstable on an axis orthogonal to the first axis corresponding to the larger beam dimension. The result is both high efficiency, excellent power and a good quality output beam is produced.

Abstract: A Q-switched laser in which the laser cavity contains on one side of the laser rod (1) a mirror (2) and on the other side of the laser rod (1) in sequence a polarizer (4) and an electro-optical cell (5) and first fold-back reflector means (3) to fold-back the beam to a second reflector (6) arranged to direct the beam back to the polarizer (4) to form a loop around the electro-optical cell (5). The mirror (2) is a partial reflector to allow output from the laser rod (1) through the mirror in pulse reflection mode or is a total reflector to allow output from the polarizer (4) in pulse transmission mode.

Abstract: The invention is a nonlinear or bistable optical device having a low switching energy. The invention uses a means responsive to light for generating a photocurrent, a structure having a semiconductor quantum well region, and means responsive to the photocurrent for electrically controlling an optical absorption of the semiconductor quantum well region. The optical absorption of the semiconductor quantum well region varies in response to variations in the photocurrent. A photodiode or phototransistor may be used as the means responsive to light, and may be made integral with the structure having the semiconductor quantum well region. An array of devices may be fabricated on a single chip for parallel logic processing.

Abstract: An optical modulator particularly suited for use as an output coupler from the resonating cavity of a laser. The modulator is fabricated with a semiconducting oxide compound selected from the group consisting of VO, VO.sub.2, V.sub.2 O.sub.3, V.sub.3 O.sub.5, V.sub.4 O.sub.6, V.sub.5 O.sub.9, V.sub.6 O.sub.11, V.sub.7 O.sub.13, V.sub.8 O.sub.15, Ti.sub.2 O.sub.3, Ti.sub.4 O.sub.7, NbO.sub.2, FeSi.sub.2, VO.sub.2 NbO.sub.2, V.sub.1-x Mo.sub.x O.sub.2, VO.sub.2 -TiO.sub.2, V.sub.2 O.sub.3 -Ti.sub.2 O.sub.3, V.sub.1-x Ge.sub.x O.sub.2, V.sub.1-x Nb.sub.x O.sub.2, V.sub.1-x Cr.sub.x O.sub.2, (Cr.sub.x V.sub.1-x).sub.2 O.sub.3 and V.sub.1-x Ti.sub.x O.sub.2. When an electric field is applied to an output coupler fabricated with a thin film or single crystal of material from the foregoing group, the material undergoes a transition between metallic and semiconducting states. In the metallic state the output coupler reflects incident luminous energy.

Abstract: The invention is a nonlinear or bistable optical device having a low switching energy. The invention uses a means responsive to light for generating a photocurrent, a structure having a semiconductor quantum well region, and means responsive to the photocurrent for electrically controlling an optical absorption of the semiconductor quantum well region. The optical absorption of the semiconductor quantum well region varies in response to variations in the photocurrent. A photodiode or phototransistor may be used as the means responsive to light, and may be made integral with the structure having the semiconductor quantum well region. An array of devices may be fabricated on a single chip for parallel logic processing.