Henk van Houten

Quantum Point Contacts

Punctuated equilibrium, the notion that evolution in nature is stepwise rather than continuous, sometimes applies to evolution in science as well. The seed of a scientific breakthrough may slumber for a decade or even longer without generating much interest. The seed may be a theoretical concept without clear predictions to test experimentally, or an intriguing but confusing experiment without a lucid interpretation. When the seed finally germinates, an entire field of science can reach maturity in a few years.

High Numerical Aperture Optical Recording : Active Tilt Correction or Thin Cover Layer?

Playback of a 12 cm diameter replicated ROM disc with a 0.6 mm substrate thickness and a storage capacity of 10 GB has been achieved using a light path with a dual-lens objective with NA=0.85 and active tilt control. The disc tilt margin exceeds ±0.7 degree. Also backward compatibility with digital versatile disc (DVD) has been demonstrated. Active tilt correction is not required for read out of a disc with a 0.1 mm transparent cover layer. This technique has also been studied experimentally. The merits and disadvantages of the two approaches are discussed.

Phase change recording

Burning data onto and off of the storage medium is such a reliable read/write method, the CD is now the worlds most popular means of distributing and exchanging prerecorded digital content.

Blue laser and high-numerical-aperture optical disk system for digital video recording (DVR)

Based on a blue diode laser (405 nm wavelength) and a two- element objective lens with a numerical aperture of 0.85, a third generation optical recording system has been developed that is able to record 22.5 GB on a single sided 12 cm diameter disc, at a user data rate of 50 Mb/s. The system is referred to by the technical name DVR for high definition Digital Video Recording. In this paper, we review the physical and the system concept, the phase change media, the optical pick up unit, and the drive implementation.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.Based on a blue diode laser (405 nm wavelength) and a two-element objective lens with a numerical aperture of 0.85, a third generation optical recording system has been developed that is able to record 22.5GB on a single sided 12 cm diameter disc, at a user data rate of 50 Mb/s. The system is referred to by the technical name DVR for high definition Digital Video Recording. In this paper, we review the physical and the system concept, the phase change media, the optical pick up unit, and the drive implementation.

Superconducting Quantum Point Contacts and Other Mesoscopic Josephson Junctions

Superconductor-two-dimensional electron gas-superconductor (S-2DEG-S) junctions derive much of their recent interest from potential applications in a three-terminal transistor based on the Josephson effect. The ability of an electric field to penetrate into a 2DEG would allow one to modulate the critical supercurrent of the Josephson junction by means of the voltage on a gate electrode, in much the same way as one can modulate the conductance of a field-effect transistor in the normal state. Of particular interest are junctions which show a quantum-size effect on the conductance, since one would then expect a relatively large field-effect on the critical current [1]. Quantum-size effects on the conductance have been studied extensively in nanostructures such as quantum point contacts and quantum dots. The corresponding effects on the Josephson current have received less attention.