Deutschetelekom Ag

California Institute of Technology

Ondax, Inc.

Karsten Buse

Demetri Psaltis

Christophe Moser

Bastian Knabe

Joerg Hukriede

Ingo Nee

Greg Steckman

Jens Kiessling

Rosita Sowade

Ingo Breunig

Matthias Falk

Gerhard Kadel

Josef Kraus

Michael Kern

Klaus Milczewsky

Hans Joachim Einsiedler

Ralph Michaels

Joseph W Goodman

Thomas Moersdorf

Daniel Haertle

Michael Koesters

Theo Woike

Konrad Peithmann

Marc Luennemann

Michael Neumann

Ali Adibi

A method for wireless data transmission between a transmitter and a receiver includes modulating signals onto an electromagnetic carrier wave in a frequency range between 0.1 and 10 terahertz, and transmitting the carrier wave by the transmitter and focusing the transmitted carrier wave in the direction of the receiver. The transmitter is aimed towards the receiver by an adjusting system using a wireless communication link between the transmitter and the receiver so as to provide automatic aiming.

Wireless data transmission with terahertz waves

A method for influencing electromagnetic radiation in a frequency range between 0.1 and 10 terahertz includes providing a planar modulator having a matrix of at least 10&#xd7;10 individual, active planar elements. Each planar element has a diameter between 5 &#x3bc;m and 100 &#x3bc;m. The planar elements are individually controlled using a central control unit such that each planar element assumes a respective one of at least two states in accordance with the control so as to influence the radiation.

Method for controlling terahertz electromagnetic carrier waves

A method for processing received electromagnetic radiation includes receiving electromagnetic radiation having a plurality of carrier waves in the frequency range between 0.1 and 10 terahertz and having modulated onto the carrier waves information with a signal frequency of less than 50 GHz. The received radiation is filtered with a filter that is tunable in the frequency range from 0.1 to 10 terahertz so as to obtain at least one carrier wave as a terahertz signal. The terahertz signal is provided to a detection circuit that is sensitive to the terahertz signal frequency.

Method and device for processing terahertz waves

A method for producing an electromagnetic carrier wave in the frequency range between 0.1 and 10 terahertz that is suitable for the wireless transmission of data includes generating, by an electromagnetic pump wave, at least two mixing waves with a defined frequency difference, the pump wave being configured to constitute one of the mixing waves; and producing an electromagnetic carrier wave by frequency mixing the mixing waves.

Method for producing terahertz electromagnetic carrier waves

Method for preparing a purified crystal for use in an optical component, from an impure crystal having impurities or crystal defects capable of causing a specific absorption of incident light, includes heating the impure crystal to a temperature at which ions in the crystal are mobile and provide conductivity. A part of the crystal is illuminated with an electromagnetic purifying beam having a frequency in or near a visible frequency range so as to optically excite and migrate charges in the crystal, the charges being compensated by a counter-migration of the ions so as to be fixed in place thereafter so as to provide a purified crystal zone. The crystal is cooled to a future operating temperature.

Optical purification of crystals

Method for treating a nominally pure crystal having non-linear optical properties. The nominally pure crystal contain foreign atoms at a residual concentration of less than 20 ppm so as to provide specific absorption of incident light. The method includes determining, based on testing on a specifically doped reference crystal of same type as the nominally pure crystal, a threshold value. The threshold value is defined by a temperature at which a migration of ions in the nominally pure crystal to the surface of the nominally pure crystal ceases. The foreign atoms are transformed to a higher valance state by a thermally-supported oxidation process including heating the nominally pure crystal at a heating rate that increases by less than 3 &#xb0; C. per minute to a maximum temperature above the threshold value and below a Curie temperature of the nominally pure crystal. An electrical voltage is applied so as to eliminate electrons released during the oxidation process from the nominally pure crystal.

Treatment of crystals for the prevention of optical damage

A method for the treatment of a crystal, such as a lithium niobate crystal or lithium tantalate crystal, having nonlinear optical properties. The crystal comprises foreign atoms which bring about specific absorption of radiated light. The foreign atoms are transformed into a lower valent state by means of oxidation. Electrons, which are released during oxidation, are discharged from the crystal with the aid of an external power source.

Treatment of crystals in order to avoid light-induced modifications of the refractive index

In the present invention, a volume holographic optical element is used as a pump coupler. The holographic coupler allows at least one pump wavelength to be coupled into the laser medium. The direction of the pump beam onto the coupler is not co-linear with the direction of the signal beam out of the coupler. The invention further provides the coupling of more than one pump wavelengths using a single holographic coupler element while maintaining the high isolation between pump and signal beam. The invention further provides a narrow-band reflection grating of various efficiencies for the signal beam (as part of the laser cavity).

Holographic pump coupler and laser grating reflector

The present invention provides a multi-channel tunable filter and methods for making such a filter. In one embodiment, the filter comprises a bank of gratings or a continuously varying filter frequency imprinted into a filter material, such as Lithium Niobate or glass or polymer. An optical read-head comprising a pair of lenses is configured to pass light from within an optical fiber carrying multiple wavelengths through an appropriate grating to extract or drop a specific wavelength. To ensure continuous data transmission, the filter is tuned to a wavelength by configuring the read-head to move in a hitless manner. In one embodiment, the gratings are recorded by the interference of two beams. A first plane wave reflects off a first mirror stack and a second plane wave reflects off a second mirror stack. In another embodiment, the gratings are recorded by a phase masking method.

Method and apparatus for implementing a multi-channel tunable filter

The present invention provides a multi-channel tunable filter and methods for making such a filter. In one embodiment, the filter comprises a bank of gratings imprinted into a filter material, such as Lithium Niobate. In another embodiment, the filter comprises a bank of gratings imprinted on a thin-film filter. An optical read-head comprising a pair of lenses is configured to pass light from within an optical fiber carrying multiple wavelengths through an appropriate grating to extract or drop a specific wavelength. To ensure continuous data transmission, the filter is tuned to a wavelength by configuring the read-head to move in a hitless manner. In one embodiment, the gratings are recorded by the interference of two beams. A first plane wave reflects off a first mirror stack and a second plane wave reflects off a second mirror stack. In another embodiment, the gratings are recorded by a phase masking method.

The present invention is a method and apparatus for a rotating, tunable, holographic drop filter connected to a fiber optic source. The filter uses a quasi phase-conjugate optical system for a drop-channel fiber coupling and WDM channels which are introduced to the system. The light from these channels is collimated and passed through a volume phase holographic material so that only one WDM channel is diffracted and the rest pass through the holographic material unaffected. A quasi phase-conjugate diffracted beam is generated by the optical system to reflect the diffracted channel back towards the holographic material. The reflected light is Bragg matched to the holographic material so that it is re-diffracted along a path identical to the original incident light beam. A free-space circulator may be used to direct the diffracted beam to a fiber optic collimator, which is different from the fiber optic collimator of the incident light beam.

Tunable holographic drop filter with quasi phase-conjugate fiber coupling

A method of and/or device for writing to an optical modulator using electromagnetic write beams, the modulator having a photorefractive converter body in which the space-modulated write beam may induce changes in the refractive index. An external voltage may be applied to the converter body. The intensity of the external voltage may be selected within a voltage range in which the buildup of changes in the refractive index may be accelerated by an increase in the charge carrier mobility or charge carrier density.

Non-linear increase in photosensitivity of photorefractive materials

An optical add/drop filter is formed using a hologram which is tuned to a wavelength in an optical signal. The diffraction condition of the hologram may be varied to vary the in add or drop content.

Tunable holographic filter

A non-volatile holographic recording method and system based on a doubly-doped photorefractive material. One embodiment of the holographic material is doped to have first and second types of dopants that are operable to produce charge carriers to a common band in response to radiation of a specified wavelengths. Charge carriers in the common band can migrate to a different spatial location. The dopants are also capable of recombining with charge carriers in the common band. The first type of dopants have a first dopant energy level below the band by a first energy gap greater than a second energy gap of a second dopant energy level of the second type of dopants below the common band. The first and second dopant energy levels are separated from each other so that their absorption bands to the common band are substantially separated. In addition, the first and second energy gaps should be much greater than the thermal energy k.sub.B T associated with the operating temperature T in order to substantially reduce or minimize the probability of thermal excitation of charge carriers.

Growing community of inventors

Bonn, Germany

Karsten Buse