Ordered magnetic nanostructures: fabrication and properties

The authors have recently demonstrated 57 nm of tuning in a monolithic semiconductor laser using conventional distributed-Bragg-reflector (DBR) technology with grating elements removed in a periodic fashion. They describe the theory and design of these so-called sampled-grating tunable lasers. They calculate sample-grating reflectivity, and present normalized design curves which quantify tradeoffs involved in a sampled-grating DBR laser with two mismatched sampled-grating mirrors. These results are applied to a design example in the InP-InGaAsP system. The design provides 70-nm tuning while maintaining >30-dB mode suppression ratio (MSR), with fractional index change Delta mu / mu >

Theory, design, and performance of extended tuning range semiconductor lasers with sampled gratings

Ion sources, systems and methods are disclosed. In some embodiments, the ion sources, systems and methods can exhibit relatively little undesired vibration and/or can sufficiently dampen undesired vibration. This can enhance performance (e.g., increase reliability, stability and the like). In certain embodiments, the ion sources, systems and methods can enhance the ability to make tips having desired physical attributes (e.g., the number of atoms on the apex of the tip). This can enhance performance (e.g., increase reliability, stability and the like).

Ion sources, systems and methods

A device for emitting radiation at a predetermined wavelength is presented. This device has a cavity with an active layer in which said radiation is generated by charge carrier recombination. The edges of the device define the region or space for radiation and/or charge carrier confinement. At least one of the edges of this cavity has a substantially random grating structure. The edge of the device has substantially random grating structure and can extend as at least one edge of a waveguide forming part of this radiation emitting device. The radiation emitting device of the present invention can have a cavity comprising a radiation confinement space that includes confinement features for the charge carriers confining the charge carriers to a subspace being smaller than the radiation confinement space within the cavity. The emitting device can comprise at least two edges forming, in cross-section, a substantially triangular shape. The angle between these two edges is smaller than 45°. At least one of the two edges has a transparent portion. the devices according to the present invention can be arranged in arrays.

Method of manufacturing surface textured high-efficiency radiating devices and devices obtained therefrom

A quantum field-effect directional coupler is described comprised of two quantum waveguides closely spaced apart with an adjacent gate electrode over the space between waveguides. The coupling of electron probability density between waveguides is controlled by the voltage applied to the gate electrode. The coupler implements a voltage-controlled current switch. Several couplers can be connected to perform multiplex/demultiplexing functions.

Quantum field-effect directional coupler

The authors propose a very simple tunable laser with a striped thin-film heater. The wavelength of this laser changes with a sensitivity of 3.2 nm/W to the input heating power. This laser can be continuously tuned over a range of 4 nm while maintaining an optical power of 20 mW and with a linewidth of less than 2.5 MHz. When this laser is mounted on a module, its 90% response time is 6 ms, which is fast enough for use as a local oscillator in several applications. >

Tunable DFB laser with a striped thin-film heater

An acoustic echo canceller system having a filter with high suppression performance of acoustic echo, generated by using microphone array having a plurality of microphone elements, judging a band where only a speaker sound is present, based on phase difference among microphones, and carrying out adaptation of an adaptive filter for only such a band.

Acoustic echo canceller system

An ion beam (113) focused into a diameter of at most 0.1 μm bombards substantially perpendicularly to the superlattice layers of a one-dimensional superlattice structure and is scanned rectilinearly in a direction of the superlattice layers so as to form at least two parallel grooves (108, 109, 110, 111) or at least two parallel impurity-implanted parts (2109) as potential barrier layers, whereby a device of two-dimensional superlattice structure can be manufactured. At least two parallel grooves (114, 115, 116, 117) or impurity-implanted parts are further formed orthogonally to the potential barrier layers of the two-dimensional superlattice structure, whereby a device of three-dimensional superlattice structure can be manufactured. In addition, deposition parts (2403, 2404, 2405) may well be provided by further depositing an insulator into the grooves (108, 109, 110, 111, 114, 115, 116, 117) which are formed by the scanning of the ion beam. Owing to these expedients, the portions of the two-dimensional and three-dimensional superlattice structures can be manufactured with ease and at high precision.

Method of manufacturing devices having superlattice structures

InGaAs/InP monolithic integrated circuits composed of a compact carrier-injection optical switch and distributed feedback laser diodes are fabricated. These integrated circuits have a variety of functions, such as monolithic modulators, switches and optical amplifiers for optical communication systems.

InGaAsP/InP monolithic integrated circuit with lasers and an optical switch

It is possible to narrow the emission spectrum linewidth of a semiconductor laser device by coupling optically an external resonator with one end surface of the semiconductor laser. However, the structure of the external resonator should match the phase of the light emitted by the laser. Heretofore, this matching has been effected by adjusting the length of the external resonator, and hence productivity and reproducibility have not been good. According to this invention, characteristics of the external resonator can be adjusted electrically to be matched with the phase of the emitted light owing to the fact that the external resonator is made of a material, whose refractive index can be varied electrically. Therefore the semiconductor laser device according to this invention is very practical.

Shinji Sakano

Papers

Tunable DFB laser with a striped thin-film heater

Acoustic echo canceller system

Method of manufacturing devices having superlattice structures

InGaAsP/InP monolithic integrated circuit with lasers and an optical switch

Semiconductor laser devices