Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Alcatel

Heinrich Hertz Institut Fuer Nachrichtentechnik Berlin Gmbh.

Technische Universitaet Darmstadt

Heinrich-Hertz-Institut Fur Nachrichtentechnik Berlin Gmbh

Bernd Sartorius

Helmut Roehle

Dennis Stanze

Roman J Dietz

Fabrice Devaux

Martin Moehrle

Harald Kuenzel

Dominique Chiaroni

Alexandre Shen

Heinz-Gunter Bach

Martin Schell

Bruno Lavigne

Tolga Tekin

Patrick Runge

Jean-Guy Provost

Michael Schlak

Roman Dietz

Carsten Bornholdt

Stephan Bauer

Cristopher Janz

Juergen Hoerer-Dragendorf

Uwe Feiste

Alain Reboux

Klaus Biermann

Bertrand Huet

Michael Feiginov

Cezary Sydlo

Harald KÜNZEL

An optical assembly for optical signal processing including a first input for coupling in a first light signal; a second input for coupling in a second light signal; a first beam splitter for splitting the first light signal into a first part and a second part; a second beam splitter for splitting the second light signal into a first part and a second part; a superposing unit; a detector; an electronic signal processing unit; at least one actuating unit; and a delay line for generating a delay of the running time of the first part of the first light signal and of the first part of the second light signal up to the superposing unit. The delay line is configured such that the first part of the first light signal and the first part of the second light signal pass through the delay line in opposite directions.

Optical assembly and method for optical signal processing

The invention relates to a method for determining the relative temporal position of electromagnetic pulses. Said method having the steps generating a sequence of first electromagnetic pulses, generating a sequence of second electromagnetic pulses, overlaying at least a part of the first and the second pulses in a saturable absorber, detecting the second pulses that have passed through the saturable absorber by means of a detector in such a manner that the second pulses, but not the first pulses that have passed through the saturable absorber, are detected, and determining the temporal position of the first pulses relative to the temporal position of the second pulses with the aid of a signal from the detector which is generated when the second pulses that have passed through the saturable absorber are received.

Method for determining the relative temporal position of electromagnetic pulses and determination device

The invention relates to a method for determining a liquid in a closed container using THz radiation, in which a first and a second measurement are carried out, wherein the THz radiation is emitted in the direction of the liquid for measuring properties of the liquid, and a portion of the THz radiation coming from the direction of the liquid is detected. In the proposed method, the closed container contains, in addition to the liquid, a gas, wherein a wall of the container is transmissive for THz radiation and wherein the detected portion of the THz radiation in the first measurement is reflected at a boundary surface between the wall and the gas or a pocket containing the gas, and the second measurement is reflected at a boundary surface between the wall and the liquid. The first measurement thus serves as a reference measurement for capturing disturbing losses in the THz beam path and for determining influences of the wall on a measurement result for the second measurement. The invention further relates to an arrangement suitable for carrying out this method.

Method and apparatus for determining a substance using THz radiation

A photoconductor comprising a layer stack with a semiconductor layer photoconductive for a predetermined wavelength range between two semiconductor boundary layers with a larger band gap than the photoconductive semiconductor layer on a substrate, wherein the semiconductor boundary layers comprise deep impurities for trapping and recombining free charge carriers from the photoconductive semiconductor layer, and two electrodes connected to the photoconductive semiconductor layer, for lateral current flow between the electrodes through the photoconductive semiconductor layer.

Fast photoconductor

A material may be identified using THz radiation that simultaneously or sequentially includes at least one first frequency portion and a second frequency portion different therefrom. An object formed from the material to be identified is irradiated with the THz radiation and the THz radiation exiting the object is detected using a phase-sensitive THz receiver. A time or phase offset, caused by the object, is measured at least for the first frequency portion and a material thickness is determined therefrom. Attenuation of the received signal, at least for the second frequency portion, is determined. An absorption coefficient for at least the second frequency portion is calculated using the material thickness.

Method and device for identifying a material

A terahertz system can be configured for producing and coherently detecting terahertz radiation. The system can comprise a laser light source and two THz antennas, a first of which is used as a transmission antenna and a second of which is used as a receiver antenna, which are each optically coupled to the laser light source by an optical fiber and can be activated by light from this laser light source, wherein the THz antennas each have a semiconductor chip to which antenna conductors have been contact-connected and which comprises at least one photosensitive active layer with a band edge wavelength which is longer than a wavelength of the laser light source and at least one layer, adjoining the active layer, with a band edge wavelength which is shorter than the wavelength of the laser light source, wherein the band edge wavelength of the active layer of at least one of the THz antennas is at least 200 nm longer than the wavelength of the laser light source.

Improved-efficiency fibre-coupled terahertz system

The invention relates to a system for producing a signal having a variably adjustable time position or phase position, comprising at least one light source for producing a first light component () having a first wavelength and a second light component (') having a second wavelength deviating from the first wavelength and a phase modulator () for varying a phase of the first light component (), wherein the system is designed to produce a beat note signal by superposing the two light components (&#x2032;) and has a common optical fiber () for coupling in both light components (&#x2032;), wherein furthermore the phase modulator () is arranged at an end or in the course of said optical fiber () and is transparent to both light components (&#x2032;) and is designed to vary the phase of the first light component () selectively independently of a phase of the second light component (&#x2032;) or more intensely than the phase of the second light component (&#x2032;). The invention further relates to a use of such a system.

Arrangement for generating a signal having an adjustable time position or phase position

The present invention relates to a device for creating and coherently detecting terahertz radiation, comprising a laser light source (), a transmission antenna () that can be activated by the laser light source () for creating the terahertz radiation, and a receiver with a receiver antenna () that can be activated by the same laser light source (), wherein the transmission antenna () comprises a photo diode as a light-sensitive element and the receiver antenna () a fast photo-conductor as a light-sensitive element. The invention further relates to a use of such a device for analyzing a sample.

Method for creating and coherently detecting terahertz radiation

Time-domain measurements are carried out using arrangements and methods. A transmitter generates electro-magnetic pulses upon receipt of pulses of an optical pulse source. A coherent detector detects the electro-magnetic pulses or an evoked electro-magnetic signal. A delay line periodically changes the optical path length between the optical pulse source and the coherent detector and/or the electro-magnetic transmitter by periodically moving an optical element of the delay line. A position sensor determines the position of the optical element and smoothes the data generated by the position sensor. The coherent detector detects the electro-magnetic signal evoked by the electro-magnetic pulses. Pulses of the optical pulse source trigger the coherent detector. The time-dependency of the electro-magnetic pulses and/or of the electro-magnetic signal evoked by the electro-magnetic pulses are determined using signals of the coherent detector upon receipt of the electro-magnetic pulses and/or of the electro-magnetic signal and the smoothed position sensor data.

Method and arrangement for carrying out time-domain measurements

A beat signal generating device including first and second monomode lasers for generating radiation of a first and second wavelengths respectively; a first and a second output port; a phase modulating unit for modifying both the phase of radiation generated by both the first laser and second laser, wherein radiation generated by the first laser is transmitted through the second laser and superposed with the radiation generated by the second laser at the second output port, and the radiation generated by the second laser is transmitted through the first laser and superposed with the radiation generated by the first laser at the first output port, such that a first beat signal will be emitted at the first output port and a second beat signal will be emitted at the second output port, wherein the phase between the beat signals can be adjusted by means of the phase modulating unit.

Beat signal generating device for use in a Terahertz system, Terahertz system and use of a beat signal generating device

An inexpensive and compact arrangement for the electrical control and fast modulation of THz transmitters and THz measuring systems is proposed, wherein said arrangement is stable, requires no mechanical movements and operates with a purely electric control, consumes little power and also has a high speed potential for the phase modulation. This is achieved by replacing the components known from the state of the art, namely two lasers, the beam splitters, the couplers and the mechanically moved delay line, with a compact monolithic or hybrid integrated chip (), particularly a so-called optical master chip without moving parts that comprises at least the two lasers (), the beam splitters (S, S), the couplers (K, K) and a phase modulator () for one of the laser waves such that the two generated beat signals are respectively delivered to different chip outputs () in order to separately control the THz transmitter and the local oscillator.

Arrangement for the electro-optical control and fast modulation of THz transmitters and THz measuring systems

An all-optical clock recovery system for recovering the clock from a received optical signal with a short response time and without patterning effects includes a first optical clock recovery device adapted to supply a first optical clock signal in response to the received optical signal and a second optical clock recovery device adapted to supply a second optical clock signal in response to the first optical clock signal. Applications include regenerating optical packets in asynchronous optical packet-switched telecommunication networks.

Optical clock recovery device for recovering the clock from an optical signal

An optical device for the differentiation of a first optical signal and an optical signal lagging behind the first, in which the differentiation is represented by a signal carried by a continuous wave passing through the two arms of an interferometer including media with an index that depends on the optical power passing through them. The delayed signal is the first signal fed back to one of the arms through a delay.

Optical differentiation device

A Q-switched semiconductor laser is supposed to facilitate high-frequency laser modulation with low currents or voltage ranges. According to the invention, a laser of this type consists of at least one continually pumped active medium and two optically coupled resonators at least one of which is passive, both resonators having different mode combs corresponding to the Nonius principle, at least one resonator mirror taking the form of a reflector with strongly dispersive reflection characteristics in the laser wavelength range selected by the double resonator, the index of refraction of the passive resonator and/or reflector capable of being adjusted electronically. With this device, the reflectivity of the laser wavelength can be adjusted in such a way that, with a fixed effective amplification by electrical modulation of the reflectivity of the resonator reflector with strongly dispersive reflection characteristics, the laser threshold can be raised or lowered so as to switch the semiconductor laser on or off.

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Berlin, Germany

Bernd Sartorius