摘要:

A uniform refractive index cladding for LiNbO3single‐crystal fibers has been achieved using a Mg ion indiffusion process. This cladding has a uniform MgO concentration of ∼20 mol %, resulting in a uniform refractive index. The refractive indices of the cladding material have been evaluated to bene=2.08 andno=2.09 at 0.6328 &mgr;m by using the light reflection technique.

ISSN:0003-6951    

DOI:10.1063/1.103025

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

GaAs/AlGaAs single quantum well lasers with integrated corner reflectors have been fabricated using chemically assisted ion beam etching. The air‐GaAs interface is internally totally reflecting, and no coherent radiation is transmitted through the corner reflector. The corner reflector laser was compared with a conventional Fabry–Perot laser cleaved from the same wafer. An 11% reduction in threshold current and a reduction of the far‐field angle from 4.4° to 0.7° was measured.

ISSN:0003-6951    

DOI:10.1063/1.103026

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The possibility of simultaneous multiple wavelength lasing in various neodymium host crystals such as Nd:YAG, Nd:YLF, Nd:BEL, and Nd:YAP has been analyzed by the ‘‘oscillation condition.’’ It is shown that this kind of laser can be realized in all the described crystals in pulsed state, but only achieved in the Nd:YAP crystal in continuous‐wave state. On the basis of the analyzed results, we have achieved cw simultaneous multiple wavelength lasing in Nd:YAP crystal for the first time at both 1.0795 and 1.3414 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.103027

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Strained single quantum well InGaAs/AlGaAs graded‐index separate confinement heterostructure lasers have been grown by molecular beam epitaxy over nonplanar substrates. In addition to the low threshold currents providedinsituby lateral current blockingpnjunctions obtained by plane‐dependent doping of the amphoteric Si dopant, we observe variations in lasing wavelength, efficiency, and internal absorption as a function of the central (100) facet length. These variations are associated with increased indium composition in the strained quantum well which arises from incorporation of adatoms migrating from the low‐growth (311)Aside facets to the preferential growth (100) active area facets. Uncoated devices (750 &mgr;m×4 &mgr;m) have been found to have threshold currents as low as 6 mA (Jth=320 A/cm2) and exhibit single‐mode behavior to greater than 100 mW at a wavelength of ∼1.0 &mgr;m when reflectivity modified (90%/10%).

ISSN:0003-6951    

DOI:10.1063/1.103028

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have fabricated a front‐surface‐emitting laser diode (FSELD) using a technique which relies on a double ion implant of oxygen and beryllium. The laser had a low operating voltage at the lasing threshold, a low series resistance, and a relatively small threshold current of 6 mA for a 25‐&mgr;m‐diam device. The lasing wavelength was 971 nm and the spectral width above threshold was 5 A˚. Since the light comes from the front surface of the wafer, the fabrication technique described here for realizing a FSELD can be used for the fabrication of vertical‐cavity visible surface‐emitting lasers.

ISSN:0003-6951    

DOI:10.1063/1.103029

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report dramatic improvements to the implanted‐planar buried‐heterostructure graded‐index separate confinement heterostructure (IPBH‐GRINSCH) laser in (AlGa)As/GaAs which produces low threshold current, continuous‐wave operation. Our process features significantly reduced fabrication complexity of high quality, index‐guided laser diodes compared to regrowth techniques and, in contrast to diffusion‐induced disordering, allows creation of self‐aligned, buried, blocking junctions by ion implantation. The improved single‐stripe IPBH‐GRINSCH lasers exhibit 39 mA threshold current, cw operation.

ISSN:0003-6951    

DOI:10.1063/1.103030

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have developed an x‐ray streak camera system with a temporal response of 2 ps (full width at half maximum). The response of the camera was measured using soft x rays in the 30 eV to 1 keV energy range which were emitted from a plasma created by a high‐intensity, subpicosecond laser pulse. A single shot, resolution‐limited, relative timing precision of 0.2 ps was demonstrated for x‐ray emission events.

ISSN:0003-6951    

DOI:10.1063/1.103031

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

With a recently developed semiconductor heterostructure it has become possible to tune continuously the electron density in multiple quantum wells. Here we demonstrate the first electro‐optic waveguide intensity modulators based on this concept. We achieve a 22 dBon/offratio for 9 V applied at 1.54 &mgr;m wavelength in a rib waveguide electroabsorption modulator. Electrorefractive devices include a waveguide Mach–Zehnder interferometer with an active length 650 &mgr;m operating at 1.58 &mgr;m wavelength with 5.4 V half‐wave voltage. We show that the operating voltage can be further reduced by operating the Mach–Zehnder modulators in push‐pull configuration.

ISSN:0003-6951    

DOI:10.1063/1.103032

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new method for studying grain boundaries of polycrystalline CdSe semiconductors by the use of photoelectrochemical etching (photoetching) has been described. The selectivity of the photoetching site of CdSe depends on the grain structure, for instance on the presence of grain boundaries or on crystallographic orientation of the grain bulk. After the photoetching treatment of CdSe under weak anodic polarization, the grain boundaries are left undissolved. This finding makes it possible to observe directly the grain boundaries as separated from the grain bulk. A transmission electron micrograph and a selected area diffraction pattern of the grain boundary are shown.

ISSN:0003-6951    

DOI:10.1063/1.103033

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The bulk metallic glass Pd40Ni40P20was prepared from the cast alloy in a belt apparatus under high pressure. The absence of crystallization in the bulk metallic glass was confirmed by x‐ray diffraction and differential thermal analysis. The microstructure of the glass was examined by scanning electron microscopy and optical microscopy.

ISSN:0003-6951    

DOI:10.1063/1.103227

出版商:AIP    

年代:1990

数据来源: AIP