Suppression of intensity fluctuation of a longitudinal mode in directly modulated GaInAsP/InP dynamic single-mode laser

The intensity fluctuation of a longitudinal mode in a modulated dynamic single-mode laser consisting of a 1.6 ?m GaInAsP/InP buried-heterostructure laser with butt-jointed built-in distributed-Bragg-reflector (BH-BJB-DBR) was suppressed to 30 dB less than that of a conventional laser. The possibility of wideband single-mode-fibre communications in the 1.5?1.6 ?m wavelength region without degradation of the bandwidth caused by mode partition noise is suggested.     

Dynamic single-mode semiconductor lasers with a distributed reflector

Recent progress in the dynamic single-mode (DSM) semiconductor lasers in the wavelength of1.5-1.6mum are reviewed and the basic principle of DSM operation is given. Study of the DSM laser is originated for application to the wide-band optical-fiber communication in the lowest loss wavelength region of 1.5 to 1.65 μm. A DSM laser consists of a mode-selective resonator and a transverse-mode-controlled waveguide, such as the narrow-striped distributed-Bragg-reflector (DBR) laser, so as to maintain a fixed axial mode under the rapid direct modulation. The technology of monolithic integration for optical circuits is applied to realize some of DSM lasers. Structures, static and dynamic characteristics of lasing wavelength, output power, and reliability of the art DSM lasers are reviewed. The dynamic Spectral width of 0.3 nm, the output power of a few milliwatts, and the reliability over a few thousand hours are reported for experimental DSM lasers.     

Single-mode oscillation under high-speed direct modulation in GaInAsP/InP integrated twin-guide lasers with distributed Bragg reflectors

Spectral behaviour of 1.3 ?m GaInAsP/InP integrated twin-guide lasers with first-order distributed Bragg reflectors under high-speed direct modulation was measured. It was confirmed that stable single-longitudinal-mode operation is maintained for applied modulating current pulse width of only 1 ns. The rise time and width of the light output pulse were less than 0.3 and 3 ns, respectively.     

Calcium and magnesium deficiency-induced atrophy of muscle and calcium accumulation in the spinal cord

Four consecutive patients with mycosis fungoides received cyclic chemotherapy using cyclophosphamide, vincristine, and prednisone (COP). In one case, there was complete remission of disease for 15 months. In another, there was 50% regression of tumors with healing of the ulcerated surfaces. The third patient showed complete clearing of scaling and redness of the skin. In the fourth patient, the lesions progressed.     

Fast pulse behaviour of InGaAsP/InP double-heterostructure lasers emitting at 1.27 ?m

The fast pulse behaviour of InGaAsP/InP d.h. lasers prepared on (100) InP substrates by liquid phase epitaxy has been studied. The possibility of high-speed direct modulation at a few gigahertz has been deduced from the relaxation oscillation characteristics.     

Facile orientation of unmodified BN nanosheets in polysiloxane/BN composite films using a high magnetic field

Composite films consisting of highly oriented boron nitride (BN) nanosheets in polysiloxane were fabricated without modifying the BN surface by applying a high magnetic field generated by a superconducting magnet. The hexagonal BN nanosheets were dispersed by sonication in a prepolymer mixture of polysiloxane. The homogeneous suspension was then cast on a polyamide spacer of microscale thickness and a magnetic field was applied before the mixture became crosslinked. The BN nanosheets in the polysiloxane were aligned with high anisotropy either parallel or perpendicular to the composite film plane depending on the magnetic flux direction. The fabricated composite films exhibited enhanced thermal conductivity by controlling the anisotropy of the BN nanosheets in the film. The mechanisms for rotation of BN nanosheets and heat diffusion across the composite film are discussed.     

Modification of BN nanosheets and their thermal conducting properties in nanocomposite film with polysiloxane according to the orientation of BN

A facile technique was developed to modify boron nitride (BN) nanosheets with iron oxides in order to fabricate highly-oriented polysiloxane/BN nanosheet composite films and their thermal properties were evaluated according to the orientation of BN. The surfaces of the BN nanosheets were modified with iron oxide nano particles by chemical vapor deposition, and their one-dimensional arrangement with variation of BN content was controlled under a magnetic field. The homogeneous suspension of BN nanosheets and pre-polymers of polysiloxane was cast on a glass spacer, and subjected to a magnetic field before the mixture was crosslinked. X-ray diffraction, transmission electron microscopy, and superconducting quantum interference device measurements were employed to identify the phases and amounts of iron oxide nano particles deposited on the BN nanosheets. The results revealed that the modified BN nanosheets were aligned either horizontally or vertically to the film plane, depending on the direction of magnetic flux with high anisotropy. The transmittance and thermal conductivity of the nano composite films were improved due to the orientation of the BN nanosheets inside the polymer matrix.     

1.53 ?m DFB lasers by mass transport

DFB lasers emitting at ?=1.53 ?m made by mass transport have been demonstrated. Output power exceeding 5 mW/ facet was obtained when operated in CW at room temperature. Single-longitudinal-mode operation with a minimum threshold current of 26 mA was achieved. No degradation can be observed after aging at 5 mW continuous power at room temperature for more than 1000 h.     

Ga0.66In0.34As/GaInAsP/InP tensile-strainedsingle-quantum-well lasers with 70-nm period wire active region

Fairly low threshold current operation was achieved with Ga_0.66In_0.34As/GaInAsP/InP tensile-strained (TS) single-quantum-well (SQW) lasers with 30-~40-nm-wide and 70-nm-period wire active region fabricated by a combination of a wet chemical etching and two-step OMVPE (organometallic vapor phase epitaxy) growth. Threshold current as low as 16 mA and threshold current density of 816 A/cm² were obtained under a room temperature CW condition. In comparing the spontaneous emission peak wavelength of the TS-SQW wire laser with that of the TS-SQW film laser, an approximately 10-meV blue shift of the fundamental energy level was observed in the TS-SQW wire laser