USA as Represented by Secretary of the Navy

Sachs/freeman Associates, Inc.

Joseph F Weller

Lew Goldberg

Henry F Taylor

Thomas G Giallorenzi

James D Crowley

William K Burns

Christen Rauscher

Scott C Rashleigh

Thomas F Carruthers

Paul T Bryant

Peter H Huang

Kiyoshi Nosu

Myung K Chun

An apparatus for generating a relatively high-power, modulated optical beam s disclosed. The apparatus comprises a first element for emitting a relatively low-power laser beam at a preselected wavelength, means for focusing the laser beam into a focused beam, a damage-resistant integrated optic modulator responsive to the focused beam for developing a modulated beam, optical means for shaping the modulated beam into a shaped modulated beam, and semiconductor means having a large active area responsive to the shaped, modulated beam for producing a relatively high-power, output modulated beam. In a first embodiment, the semiconductor means is a semiconductor amplifier which amplifies the modulated beam to produce the high-power, modulated output beam.

Modulated high-power optical source

A bi-directional optical transmission system for radio frequency electrical nergy includes first and second transmitter/receiver stations which transmit and receive light signals along an optical path therebetween. Each station includes a laser transmitter for transmitting a carrier light beam which is intensity modulated by a synchronization of an input radio frequency electrical signal. A photodetector at each station detects the intensity variations of the carrier light beam from the other station and outputs a respective radio frequency electrical signal which is synchronized with the radio frequency electrical input signal of the other station. A beam splitter is provided between the optical path at both the laser transmitter and photodetector to split the light beams incident thereon into a pass portion and angularly reflected portion. An isolator device also is provided between the laser transmitter and beam splitter to isolate the laser transmitter from back reflections. Preferably, the isolator is a Faraday isolator, and additionally or alternatively the laser transmitters transmit at widely separate wavelengths. The optical path can either be free space or a main optical fiber, and the synchronization of the input radio frequency electrical energy can either be phase synchronization or time synchronization.

Bi-directional optical transmission system for RF electrical energy

An apparatus for generating coherent radiation at a desired frequency is disclosed. In a preferred embodiment the apparatus comprises: an injection-locked semiconductor diode structure having a large active area for emitting a diffraction-limited beam at a preselected frequency; optics for focusing the diffraction-limited beam into a focused beam; a nonlinear crystal responsive to the focused beam for producing a beam of laser power which includes an output beam at a desired harmonic of the preselected frequency; and a device for passing the output beam in a given direction. In a modification of the preferred embodiment, the output of the injection-locked semiconductor diode structure is mixed with an emission from a laser source in the nonlinear crystal to produce a desired sum or difference frequency.

Apparatus for the efficient wavelength conversion of laser radiation

A semiconductor laser structure for generating high frequency modulation of light intensity is disclosed. The apparatus comprises a seminconductor substrate, a semiconductor master laser and first and second semiconductor slave lasers fabricated adjacent to each other on the semiconductor substrate. Bias current applied to the master oscillator is modulated at a preselected frequency to cause the master laser to generate a plurality of optical frequency modulation sidebands. The first and second slave lasers, which are tuned to be close to the preselected first and second sidebands of the master laser, are injection-locked to the first and second preselected sidebands of the master laser.

Monolithic laser diode structure for microwave generation

Diffraction limited, single narrow lobe radiation from a large area laser is achieved in a system using an external ring laser cavity to return radiation to the laser via a spatial filter and a Faraday rotator. An antireflectance coating of sufficiently small reflectivity added to the large area laser converts it into a laser amplifier which provides optical gain in a ring laser cavity.

Ring laser cavities

An apparatus for amplifying a laser beam through injection locking of a laser array by a single master laser is presented. The apparatus is comprised of a master laser which produces a beam that is shaped or focused onto a laser array facet which is further comprised of an array junction plane wherein the laser array is biased above threshold.

Optical injection locking of laser diode arrays

An acousto-optic frequency shifter in which two cylindrical acoustic resonators driven 90.degree. out of phase from one another are placed around a birefringent, single-mode optical fiber approximately three-quarters of a polarization beat length apart. The resonators interact with optical radiation propagating in one of two polarization modes of the fiber, the first to cross-couple two sidebands into the other polarization mode, and the second to suppress one of the sidebands in the cross-coupled mode and enhance the other, thereby creating a single sideband signal completely within the fiber.

Method and apparatus for acousto-optically shifting the frequency of a

An optical frequency division multiplex system including a transmitter, a receiver, and a transmission path connecting the transmitter to the receiver. In the transmitter a master laser is operated to produce a central peak at an optical frequency f.sub.o with side peaks separated by an amount .DELTA.f running to both sides of the central peak. The master laser output goes through an optical isolator to an optical coupler where it is split up into N+1 beams. Each optical output from the coupler is then positioned to be coupled into N slave lasers. Each slave laser is tuned to approximately coincide with one of the side peaks thus producing a single output frequency of (f.sub.o .+-.n.DELTA.f) from each slave laser diode. Electrical modulating signals for each of N information channels are applied separately to modulate the phase of each of the slave laser outputs. The outputs of the slave lasers are then recombined in a N.times.1 optical coupler, the output of which is transmitted over a single-mode fiber linking the transmitter to the receiver. One of the outputs of the 1.times.(N+1) coupler is transmitted to the receiver over a second single-mode fiber. At the receiver, the master laser carrier is split into N spatial components by a 1.times.N coupler. These are then filtered and amplified by a second group of N slave lasers. The output from this second unmodulated group of slave lasers is combined with the combined outputs from the modulated slave lasers in an array of 2.times.1 optical couplers. Finally, the light signals emerging from the couplers are converted to electrical signals for the N information channels by an array of photodetectors.

Frequency multiplex system using injection locking of multiple laser

Laser linewidth is controlled by reflecting a certain portion of the laser light back into the laser cavity. This control is accomplished by aligning the active layer on an electroabsorptive cell with the active layer of a semiconductor laser on a single substrate with a first waveguide therebetween. Light from the laser is guided by the first waveguide to the electroabsorptive cell whose light absorption is electronically controlled. The laser light propagates through the active region in the electroabsorptive cell and then is guided by a second waveguide to a reflection facet. The laser light is reflected by this reflection facet back through the waveguide-cell-waveguide-laser light path. The foregoing device can be formed using either a monolithic or a hybrid design.

Controlled-linewidth laser source

The optical injection-locking of an FET oscillator is accomplished by injecting the beat signal between two coherently mixed slave lasers, which are locked to different harmonics of a modulated master laser, into the FET oscillator to be locked. 120 GHz injection-locking beat signals are possible using this technique.

Optical injection locking of solid-state oscillators by

Transferred-electron device (TED) microwave burst and single pulse generators which are triggered by picosecond optical pulses. The burst generator includes a TED having a cathode, an anode, and a gate electrode positioned therebetween, all located on a semiconductor substrate. An optical pulse applied to the substrate between the gate and anode electrodes causes a plurality of space charge domains to sequentially travel from the gate to the illuminated region thereby causing an oscillatory burst of current to occur in the external leads of the TED. The frequency of the burst is proportional to the distance between the gate and the illuminated region and the burst duration is proportional to the optical pulse amplitude and/or duration. Alternatively, the burst generators may be formed from a two terminal TED with the cathode electrode being treated as the gate. A single pulse generator may be formed by applying an optical pulse to the substrate between the cathode and the gate of a three terminal TED. The duration of the single pulse is proportional to the distance between the gate and the anode.

Optically triggered transferred-electron device microwave burst and

Coupling devices for SAW's, which permit switching of SAW power between cnels. Channel waveguides are laid down on or in the surface of a substrate. The waveguides have a coupling region in which they are close to each other. The input waveguide is formed from a material whose acoustic wave velocity characteristic can be changed by an external means. Various means for altering the velocity of the SAW, such as electric or optical fields, are employed by applying them to the coupling region of the input waveguide.

Active waveguide coupler for surface acoustic waves

A surface acoustical wave (SAW) waveguide device which compensates for dispersion by utilizing diffused substrates. Various embodiments have in-diffused or out-diffused core regions in which the ray is channeled that are topped by a thin metallic film overlay. Partially surrounding each core region are cladding portions which are also selectively in-diffused or out-diffused and may be covered by the metal overlay. By varying the amounts of in-diffusion or out-diffusion for the particular application, the effects of dispersion are minimized.

Dispersion compensated acoustic surface waveguides using diffused

Two input transducers launch oppositely-propagating acoustic surface waves on a piezoelectric substrate. The waves are compressed to a smaller beamwidth and then laterally confined in a diffused channel waveguide where non-linear interaction occurs at increased energy densities due to the beam compression. In one embodiment the beam compression is accomplished in multistrip couplers. In another embodiment, diffused horn-shaped channels are provided for compressing the beamwidth. Both piezoelectric and semiconductor convolvers are disclosed.

Acoustic-wave convolvers utilizing diffused waveguides and beam

A tapped surface acoustic wave (SAW) delay line with time-resolved outputs sing piezoelectric leaky wave coupling and bulk wave amplification, and having low loss characteristics. A solid piezoelectric semiconductor is placed adjacent to a solid piezoelectric substrate. A pulsed rf input signal is applied to interdigital transducers (IDT) on the substrate. The applied signal launches a SAW in the substrate in a direction parallel to the interface between the substrate and the piezoelectric semiconductor solid. Upon reaching the interface, the SAW is piezoelectrically leaky-wave coupled across an air gap to a bulk acoustic wave in the piezoelectric semiconductor. Reflections of the bulk wave occur at both surfaces of the piezoelectric semiconductor, and piezoelectrically couples back across the air gap to excite a SAW on the piezoelectric substrate. The resultant rf output includes the normal delayed SAW pulse and additional delayed and time-resolved pulses. The amplitude of the bulk wave may be increased using bulk wave amplification.

Growing community of inventors

Fort Washington, MD, United States of America

Joseph F Weller