Helmut Appel - Academia.edu (original) (raw)
Uploads
Papers by Helmut Appel
Advances in Optoelectronics, 2007
We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subter... more We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subterahertz frequency (near 300 GHz). The oscillator is driven by a microwave source (frequency near 100 GHz). We also present an analysis indicating that operation at frequencies above 1 THz should be possible. The SPO is based on the ability of conduction electrons in a superlattice to perform Bloch oscillations. Broadband tunability as well as the monochromacy of a driving microwave field are transferred to the SPO.
Arxiv preprint cond-mat/ …, 2005
Abstract: We report the operation of a Bloch oscillator. The active medium was a staticvoltage dr... more Abstract: We report the operation of a Bloch oscillator. The active medium was a staticvoltage driven, doped GaAs/AlAs superlattice which was electromagnetically coupled to a resonator. The oscillator produced tuneable microwave radiation (frequency~ 60 GHz; ...
… and Propagation, IEE …, 2006
We report on a semiconductor-superlattice oscillator with a superlattice electronic device (SLED)... more We report on a semiconductor-superlattice oscillator with a superlattice electronic device (SLED) containing superlattices connected in parallel and series as active elements for generation of millimetre waves. We present experimental results indicating that parallel ...
Advances in OptoElectronics, 2007
We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subter... more We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subterahertz frequency (near 300 GHz). The oscillator is driven by a microwave source (frequency near 100 GHz). We also present an analysis indicating that operation at frequencies above 1 THz should be possible. The SPO is based on the ability of conduction electrons in a superlattice to perform Bloch oscillations. Broadband tunability as well as the monochromacy of a driving microwave field are transferred to the SPO.
Electronics Letters, 2003
Abstract A fabrication technique for a waveguide cavity with submillimetre dimensions is reported... more Abstract A fabrication technique for a waveguide cavity with submillimetre dimensions is reported. The cavity was composed of galvanoformed nickel structures. A mould for the galvanoforming was made from a thick-film UV-photoresist. Using a semiconductor ...
Advances in Optoelectronics, 2007
We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subter... more We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subterahertz frequency (near 300 GHz). The oscillator is driven by a microwave source (frequency near 100 GHz). We also present an analysis indicating that operation at frequencies above 1 THz should be possible. The SPO is based on the ability of conduction electrons in a superlattice to perform Bloch oscillations. Broadband tunability as well as the monochromacy of a driving microwave field are transferred to the SPO.
Arxiv preprint cond-mat/ …, 2005
Abstract: We report the operation of a Bloch oscillator. The active medium was a staticvoltage dr... more Abstract: We report the operation of a Bloch oscillator. The active medium was a staticvoltage driven, doped GaAs/AlAs superlattice which was electromagnetically coupled to a resonator. The oscillator produced tuneable microwave radiation (frequency~ 60 GHz; ...
… and Propagation, IEE …, 2006
We report on a semiconductor-superlattice oscillator with a superlattice electronic device (SLED)... more We report on a semiconductor-superlattice oscillator with a superlattice electronic device (SLED) containing superlattices connected in parallel and series as active elements for generation of millimetre waves. We present experimental results indicating that parallel ...
Advances in OptoElectronics, 2007
We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subter... more We describe the operation of a semiconductor-superlattice parametric oscillator (SPO) at a subterahertz frequency (near 300 GHz). The oscillator is driven by a microwave source (frequency near 100 GHz). We also present an analysis indicating that operation at frequencies above 1 THz should be possible. The SPO is based on the ability of conduction electrons in a superlattice to perform Bloch oscillations. Broadband tunability as well as the monochromacy of a driving microwave field are transferred to the SPO.
Electronics Letters, 2003
Abstract A fabrication technique for a waveguide cavity with submillimetre dimensions is reported... more Abstract A fabrication technique for a waveguide cavity with submillimetre dimensions is reported. The cavity was composed of galvanoformed nickel structures. A mould for the galvanoforming was made from a thick-film UV-photoresist. Using a semiconductor ...