Abstract: A frequency converter and a method in a frequency converter. The frequency converter is adapted to drive an electrical load, wherein the frequency converter comprises a communications interface through which the frequency converter is adapted to receive external requests to change input power of the frequency converter, means adapted to hold one or more conditions for allowing to change the input power of the frequency converter, and processing means adapted to change the input power of the frequency converter upon receipt of the external request in the limits set by the one or more conditions. (FIG.

Abstract: A low-noise directional amplifier includes a first port, a second port, a first coupler and a second coupler. The first port is coupled to a first coupler. The low-noise directional amplifier also includes at least two phase preserving amplifiers, a first phase preserving amplifier connected to the first coupler and a second coupler, and the second phase preserving amplifier connected to the first coupler and the second coupler.

Abstract: Systems and methods for controlling optical feedback in an optical system having a radiation source optically coupled via mode matching optics with a resonant optical cavity. The cavity includes at least two cavity mirrors, one of which is a cavity coupling mirror, and has a plurality of optical resonance cavity modes, wherein the radiation source emits a beam of continuous wave radiation and is capable of being scanned whereby a mean optical frequency of the continuous wave radiation beam is adjustable over a range of frequencies, wherein the radiation source is responsive to optical feedback radiation emerging from the cavity, and wherein the mode matching optics couples the beam of continuous wave radiation to the cavity via the cavity coupling mirror. The radiation source and the mode matching optics are aligned so that a mode fill ratio is reduced relative to a maximum mode fill ratio, wherein for the maximum mode-fill ratio the laser beam is coupled with a fundamental cavity mode.

Abstract: Systems and methods for extending coverage of a communication network. In one embodiment, a system includes a first base station configured to communicate with a first mobile communication device and to generate a core interface message. The system also includes a second mobile communication device and an application level server. The second mobile communication device is connected to the first base station and is configured to obtain the core interface message from the first base station, generate a message including the core interface message in an application layer of the message, address the message to the application level server, and transmit the message to the application level server. The application level server is configured to receive the message, extract the core interface message from the message, and transfer the core interface message to a network core to emulate an interface between the first base station and the network core.

Abstract: Radio-frequency (RF) integrated circuit (RFIC) chip(s) allow for the integration of multiple electronic circuits on a chip to provide distributed antenna system functionalities. RFIC chips are employed in central unit and remote unit components, reducing component cost and size, increasing performance and reliability, while reducing power consumption. The components are also easier to manufacture. The RFIC chip(s) can be employed in distributed antenna systems and components that support RF communications services and/or digital data services.

Abstract: Coverage for a wireless network is improved using a frequency shifting scheme. A wireless signal in a frequency band is shifted to another band, and carried in the shifted band to another location where the signal is shifted back to the original frequency band. The frequency shifting may utilize frequency shifting schemes such as mixer/filter and heterodyne. The wireless signal can be frequency shifted by converting it to other representing signals (such as I/Q components) and forming the frequency-shifted signal from the representations. The transmission medium may use dedicated wiring or existing service wiring in a residence or building, including LAN, telephone, AC power and CATV wiring. The system may be enclosed as a stand-alone unit, housed in integrated form as part of a service outlet or as a snap-on/plug-in module.

Abstract: Systems, methods and apparatus for improving the coverage of a wireless network based on frequency shifting scheme. A wireless signal in a frequency band is shifted to another distinct band, and carried in the shifted band, using wired or wireless mediums to another location, wherein the wireless signal is shifted back to the original frequency band. The frequency shifting may make use of a conventional frequency shifting schemes such as mixer/filter and heterodyne. In one embodiment the wireless signal is frequency shifted by converting it to other representing signals (such as I/Q components) and forming the frequency-shifted signal from the representations. The system is may be used to increase in-door or outdoor coverage, as well as bridging between in-door and outdoor networks. The medium may use dedicated wiring or existing service wiring in a residence or building, including LAN, telephone, AC power and CATV wiring.

Abstract: Systems, methods and apparatus for improving the coverage of a wireless network based on frequency shifting scheme. A wireless signal in a frequency band is shifted to another distinct band, and carried in the shifted band, using wired or wireless mediums to another location, wherein the wireless signal is shifted back to the original frequency band. The frequency shifting may make use of a conventional frequency shifting schemes such as mixer/filter and heterodyne. In one embodiment the wireless signal is frequency shifted by converting it to other representing signals (such as I/Q components) and forming the frequency-shifted signal from the representations. The system is may be used to increase in-door or outdoor coverage, as well as bridging between in-door and outdoor networks. The medium may use dedicated wiring or existing service wiring in a residence or building, including LAN, telephone, AC power and CATV wiring.

Abstract: A PWM cycloconverter easily capable of improving an input current waveform and regenerating energy of a snubber into a power source is provided. A PWM cycloconverter includes a PWM converter connected to a DC voltage system. An output unit of the PWM converter is connected to a place before an input filter of the PWM cycloconverter to keep down resonance of the input filter.

Abstract: The present invention is an optical parametric oscillator (OPO) which combines a singly resonant oscillator (SRO) configuration with a buildup cavity and uses optical output of a buildup cavity as feedback to injection lock a source laser. The result is an easily tuned OPO with a low pump power threshold without the requirement for active electronic control of the laser and/or the OPO resonator. In particular, specific embodiments of the invention employ a semiconductor diode laser to pump the OPO. The emission from the single longitudinal mode diode laser is transversely mode matched into the buildup cavity where the circulating power can build up to hundreds of times the output power of the diode. This high circulating power traverses the OPO crystal at a point of focus, producing a high enough intensity for operation of the OPO. At least one of the generated waves is also resonated in the SRO configuration.

Abstract: The invention relates to a low-noise amplification device of an optical wave. Signal wave (F.sub.s) to be amplified interferes with a pump wave (F.sub.p) in such a nonlinear medium (1) as a photorefractive crystal. To reduce the noise considerably, even to eliminate it, the establishing of noise-generating interferences therefore is prevented by moving, by rotation around an axis O, the nonlinear medium.

Abstract: An optical waveguide for transmitting light energy is defined by a glass capillary with a core of noncentrosymmetric non-linear optical polymer which has been poled to induce a stable axial alignment of molecules therein. Changes in refractive index of the polymer are induced by an applied electric field. In a preferred embodiment, the waveguide is used as an electric field sensor and may form an arm of a Mach-Zender interferometer. The device is adapted to modulate waveguided electromagnetic energy by a change in refractive index proportional to the applied electric field. In a further embodiment, the birefringent properties of the polymer are used to cause polarized light energy transmitted by the waveguide to undergo a change in polarization, which, when intercepted by a polarization sensitive analyzer, provides an amplitude modulation of the transmitted light energy.

Abstract: A distortion free fiber optic system having a single-mode optical fiber utilized in combination with a semiconductor material mounted in optical alignment therewith. Although it is preferable for the semiconductor material to be adjacent the input end of the fiber, it may, in the alternative, be placed adjacent the output end of the fiber. For appropriate distortion free propagation of a beam of electromagnetic radiation through the optical fiber, the semiconductor material must be receptive to the wavelength of the electromagnetic beam. This can be accomplished by either matching the semiconductor material to the wavelength of the beam or tuning the source of the electromagnetic beam to the excitonic-polariton resonance of the semiconductor crystal.

Abstract: A surface-acoustic-wave device wherein a plurality of metal strips (S) are provided on a propagation path of surface acoustic wave which is formed in a laminate comprised of a piezoelectric layer (23) and a semiconductor (1), the metal strips are extended onto the semiconductor outside the propagation path of surface acoustic wave, and depletion layer capacitance non-linearity created on the semiconductor surface at a region where the metal strips are extended is used as a main factor of a parametric interaction.

Abstract: A parametric amplifier including a semiconductor body portion (10) comprising a plurality of zones (11,13,15, . . . ) of a first conductivity type, each of the zones having a thickness less than or equal to the Debye length in the semiconductor body portion (11,13,15, . . . ), each of the zones being separated from one another by corresponding insulating layers (12,14, . . . ). The body portion has a first edge portion abutting a first edge of the plurality of zones, and a second edge portion abutting a second edge of the plurality of zones spaced apart from said first edge.A first interface (20) is provided adjacent the first edge portion for transmitting an electromagnetic wave into the semiconductor body portion for propagation therein; and a second interface (21) is provided adjacent the second edge portion for receiving an electromagnetic wave propagating in the body portion.

Abstract: A surface-acoustic-wave device has a laminate formed of a semiconductor and a piezoelectric layer and a depletion layer control means locally provided at an interface portion of the semiconductor and said piezoelectric layer, wherein a parametric interaction is caused at a region other than an area where the depletion layer control means is provided and a depletion layer capacitance is controlled by applying a DC bias voltage and a pumping voltage to the depletion layer control means.

Abstract: The present invention relates to a subharmonically pumped hysteretic superconductor-insulator-superconductor (SIS) junction mixer. The hysteretic junction (10), achieved by not suppressing the critical current I.sub.c of the junction, is responsive to a first source of a pump signal (12) at a frequency .omega..sub.p and a second source of an input signal (14) at a frequency .omega..sub.i, to produce a non-zero output signal at a frequency .omega..sub.o =.vertline..omega..sub.i -2.omega..sub.p .vertline., during either an overpumped or underpumped condition. The hysteretic nature of the junction allows the mixer to operate in a switching mode, thereby producing low-noise mixing with gain.

Abstract: In a microwave circuit for a parametric upper sideband down converter with real image frequency termination conductance, including a pump circuit supplying a pump signal, a parallel circuit at its input, an intermediate frequency circuit at its output, and a reactance diode coupling the parallel circuit and intermediate frequency circuit together, the parallel circuit is tuned approximately to the frequency of the pump signal; the intermediate frequency circuit is composed of a .pi.

Abstract: A coherent tunable narrow band IR source in the vicinity of 16 .mu.m is achieved by four-wave parametric mixing in parahydrogen. A pair of colinear laser beams, one from a narrow band CO.sub.2 laser, and a second from a multiline laser with output of wave number significantly below 14,400 cm..sup.-1, is focused in a parahydrogen containing cell. The multi-line laser beam drives a Raman process in the cell. The narrow band CO.sub.2 input beam mixes with this driver beam and the Stokes wave resulting from the Raman process to produce a 16 .mu.m output beam. Tuning of the CO.sub.2 laser allows tuning of the 16 .mu.m radiation emitted by the parahydrogen cell.

Abstract: An elastic surface wave device, especially amplifier which includes input and output means for electrical signals provided so as to be spaced on a surface of a piezoelectric material which composes a laminate in combination with a semiconductor, and an electrode provided in a surface signal wave propagation path between said input and output means for application of a d.c. bias voltage and supply of a pumping power.

Abstract: A device for shifting the frequency of infrared radiation from a CO.sub.2 laser by stimulated Raman scattering in either H.sub.2 or D.sub.2. The device of the preferred embodiment comprises an H.sub.2 Raman laser having dichroic mirrors which are reflective for 16 .mu.m radiation and transmittive for 10 .mu.m, disposed at opposite ends of an interaction cell. The interaction cell contains a diatomic molecular gas, e.g., H.sub.2, D.sub.2, T.sub.2, HD, HT, DT and a capillary waveguide disposed within the cell. A liquid nitrogen jacket is provided around the capillary waveguide for the purpose of cooling. In another embodiment the input CO.sub.2 radiation is circularly polarized using a Fresnel rhomb .lambda./4 plate and applied to an interaction cell of much longer length for single pass operation.

Abstract: A single varactor diode parametric amplifier is described which has a broadband termination at the upper sideband frequency in the pump waveguide. This termination presents an open circuit condition at the upper sideband frequency, which, in combination with an upper sideband fequency choke on the input signal circuit transmission line achieves low noise, high gain characteristics with minimum interaction with the input signal, pump, and idler circuitry. Theoretical noise figures can be obtained at low power consumption, high gain, and broadband performance.

Abstract: Parametric coupling device for traveling-waves, comprising a first signal wave, a second idler wave and a third pump wave, wherein a transmission line for said traveling-waves is formed on a substrate of dielectric material, which comprises a virtually continuous network of non-linear interaction elements, modulated by the pump wave, and so modulating the conduction properties of the transmission line and enabling intermodulation to be set up between the various traveling-waves. The virtually continuous network of non-linear interaction elements is a substantially plane network, each non-linear interaction element being at a distance a, or pitch of the network, from a neighbouring non-linear element, the distance a being less than the smallest of the wavelength of the signal, idler and pump waves and the plane network being disposed in the neighborhood of the upper surface of the transmission line.