A highly efficient channel drop filter. The filter employs a coupling element including a resonator-system between two waveguides, which contains at least two resonant modes. The resonator-system includes one or more interacting resonant cavities which in addition to being coupled to the waveguides, can also be coupled directly among themselves and indirectly among themselves via the waveguides. Each component of the coupling element can be configured or adjusted individually. The geometry and/or dielectric constant/refractive index of the resonator-system are configured so that the frequencies and decay rates of the resonant modes are made to be substantially the same. The filter can achieve 100% signal transfer between the waveguides at certain frequencies, while completely prohibiting signal transfer at other frequencies. In exemplary embodiments, the filter is configured with photonic crystals. In accordance with alternative embodiments of the invention, the filter is configured as an absorption induced on/off switch and modulator. The switching action is achieved with either electrical or optical absorption.

High efficiency channel drop filter with absorption induced on/off switching and modulation

A periodic dielectric structure and method of fabricating same, the structure having a three-dimensional photonic bandgap. The structure includes a plurality of layers, at least one layer having a stratum of a first material having a first dielectric constant and a plurality of parallel grooves along a first axis lying in the plane of the layer, the grooves including a second material having a second dielectric constant; and a plurality of parallel channels formed through the plurality of layers in a second axis orthogonal to the plane of the layers, the channels being adapted to comprise a third material having a third dielectric constant, thereby resulting in the structure having three-dimensional periodicity. In preferred embodiments, the second and third materials include air.

Three-dimensional periodic dielectric structures having photonic bandgaps

The present invention provides a resonant cavity including a planar two-dimensional periodic dielectric structure which exhibits a photonic band gap and a defect in the periodic dielectric structure which results in an electromagnetic mode within the photonic band gap. The photonic band gap effects an in-plane spacial confinement of electromagnetic radiation generated within the structure. The electromagnetic radiation is vertically confined by total internal reflection.

Resonant cavities employing two dimensionally periodic dielectric materials

A cooling/heating circuit for a vehicle with at least two constituent circuits, which are at least in part at different temperatures and each contain at least one cooler for cooling at least one assembly in each case, the constituent circuits being coupled fluid-mechanically to one another.

Vehicle cooling/heating circuit

We report results of the development of fast closing switches, so-called pseudospark switches, at Erlangen University. Two different parameter regimes are under investigation: medium power switches (32 kV anode voltage, 30 kA anode current and 0.02 C charge transfer per shot) for pulsed gas discharge lasers and high power switches (30 kV anode voltage, 400 kA anode current and 3.4 C charge transfer per shot) for high current applications. The lifetime of these switches is determined by erosion of the cathode. The total charge transfer of devices with one discharge channel is about 220 kC for the medium and 27 kC for the high power switch. At currents exceeding 45 kA a sudden increase in erosion rate was observed. Multichannel devices are suited to increase lifetime as the current per channel can be reduced. Successful experiments with radial and coaxial arrangements of the discharge channels were performed. In these systems the discharge channels move due to magnetic forces. A skilful use of this phenomena will result in a considerably increase of switch lifetime. Multigap devices enable an increase of anode voltage. A three gap switch has run reliably at an anode voltage of 70 kV. >

Pseudospark switches-technological aspects and application

Integrated resonator matrix for wavelength-selective separation or joining of channels in the frequency domain of optical communications technology. Arrangement of optical resonators which are composed of dielectric waveguides which are mirrored at their ends predominantly with reflectors having high reflection factors close to the value one and whose longitudinal extent between the reflectors is great in comparison to the transverse dimensions perpendicular thereto, all optical resonators are integrated such on a substrate to form a matrix-like arrangement, referred to as resonator matrix. Two types of resonators can be distinguished, whereby the resonators of the first type are highly coupled to one another and act as coupled resonators (22, 221, 222), whereas the resonators of the second type act as wavelength-selective useful resonators (23, 231, 232) and, compared to the couplings between the resonators of the first type, are weakly coupled to one another or, respectively, to the resonators of the first type and form at least two useful resonator groups which are not coupled to one another (or are coupled to one another as little as possible) whereby a useful resonator group contains one or more useful resonators.

Integrated resonator matrix for wavelength-selective separation or joining of channels in the frequency domain of optical communications technology

A fiber optic gyroscope different from the standard concept is presented. A fused fiber 3 x 3 directional coupler provides a constant phase shift thus enabling the detection of rotation rate at the quadrature point without phase modulation. Bias errors due to birefringent coupling centers in the fiber coil are avoided by using an unpolarized light source. A contrast insensitive signal recovery scheme eliminates the influence of polarization fluctuations on the scale factor. First measurements with a prototype gyroscope (90 mm in diameter and 23 mm in height) show a bias stability of <4.7 degrees /h and scale factor accuracy of <0.1% in the range of +/-200 degrees /s.

Passive fiber optic gyroscope

In the present process for operating a fuel cell installation (2) comprising at least one fuel cell block (4), a process gas for the fuel cell block (4) is fed into the fuel cell block (4) using a liquid ring compres-sor (6) . By virtue of this measure, the process gas is humidified at the same time as it compressed.

Process for operating a fuel cell installation and fuel cell installation for carrying out the process

In the present invention for operating a fuel cell installation (2) comprising at least one fuel cell block (4), a process gas for the fuel cell block (4) is fed thereinto by a liquid ring compressor (6). The process gas is thereby simultaneously compressed and moistened.

Process for operating a fuel cell installation and fuel cell installation for implementing it

A high-energy TE laser system, includes an excitation circuit, a laser head having an optical axis, a laser chamber with a gas space formed therein, at least two laser electrodes being disposed opposite each other and spaced apart in the laser chamber parallel to the optical axis of the laser head for producing an arc-free capacitor discharge between the electrodes being as homogenous as possible in the gas space for excitation, at least one rapid high-voltage switch, a pulse-forming network connected to the rapid high-voltage switch for producing high-voltage pulses at the laser electrodes with the rapid high-voltage switch, the pulse-forming network including first and second strip conductor capacitors respectively associated with the rapid high-voltage switch and with the laser head, the strip conductor capacitors including plates and dielectric layers disposed between the plates extended substantially normal to the optical axis of the laser head, forming a capacitor stack stacked substantially parallel to the optical axis of the laser head, the plates being connected in the pulse-forming network, the pulse-forming network being a Blumlein circuit in which at least one plate of the second strip conductor capacitor is connected to one of the laser electrodes, and the plates being divided into n adjacent plate sections having n-1 partings respectively disposed therebetween, and coupling inductances conductively connecting the plate sections to each other. Otherwise, the pulse-forming network is a charge-transfer circuit in which at least a partial surface of the plates of the first and second strip conductor capacitors are connected in common to one of the laser electrodes.

Reinhard Muller

Papers

Integrated resonator matrix for wavelength-selective separation or joining of channels in the frequency domain of optical communications technology

Passive fiber optic gyroscope

Process for operating a fuel cell installation and fuel cell installation for carrying out the process

Process for operating a fuel cell installation and fuel cell installation for implementing it

High-energy laser system