摘要:

Data are presented demonstrating photopumped laser operation of a planar photonic lattice (∼1 &mgr;m thick) that is comprised of 9 &mgr;m disks with 2 &mgr;m separation arranged in a two‐dimensional hexagonal close‐packed pattern. The active region of each disk is an AlAs (70 A˚)–GaAs (30 A˚) superlattice (100 periods). The disks are defined by impurity‐induced layer disordering, followed by wet oxidation (N2+H2O vapor, 400  °C), which surrounds each disk with a low‐refractive‐index AlGaAs native oxide. The photonic lattice exhibits laser operation within wide (&Dgr;&lgr;∼17 A˚) spectral bands that are spaced according to the disk modes, and that propagate light anisotropically in the plane of the lattice. In addition to the extended lattice, groups of seven disks are studied and are seen to display similar behavior. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116294

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have demonstrated wavelength conversion in the 1.5 &mgr;m regime using the near band gap nonlinearity of semiconductor quantum wells. In a 7.5 mm long passive InGaAsP/InP single quantum well waveguide, a wavelength shift of 20 nm has been obtained with −11 dB conversion efficiency using picosecond pulses. We confirmed the ultrafast nature of the nonlinearity by measuring the conversion efficiency as a function of the frequency shift. An order of magnitude increase in the value ofn2close to the band gap is observed compared with the off‐resonance value. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116295

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We demonstrate the direct writing of GaAs waveguide structures by selective area deposition using laser‐assisted chemical vapor deposition (LCVD). The multimode waveguides have a Gaussian shape and a very smooth surface, and they exhibit losses as low as 5.4 dB/cm. The LCVD technique offers the capability of selective growth of independent device structures, and hence the capability of monolithic integration of these devices for optoelectronic applications. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116296

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

It is demonstrated that placing ann‐type Te &dgr; doping aside a single strained quantum well (QW) is an efficient way to control the initial carrier concentration in the QW and thus to lower transparency current density,Jtr, while preserving low internal losses. This is in contrast with uniform doping of the active area.Jtrof 11.3 A/cm<thin>2and threshold current density of 54.4 A/cm2, which are both the lowest values reported to date for strained InxGa1−xAs/GaAs semiconductor lasers, were obtained. A somewhat higher injection efficiency is obtained when the energy levels are adjusted so that the electrons tunnel from the delta well directly into the QW. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116297

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The C 1sand O 1score‐level photoabsorption spectra of poly[2‐methoxy,5‐(2′‐ethyl‐ hexoxy)‐1,4‐phenylene vinylene] (MEH‐PPV) before and after exposure O2and broadband visible light were recorded to determine the degradation pathway for this polymer. The change in the O 1sspectra as a function of exposure demonstrates that the O adds to the polymer chain to form a carbonyl group. Exposure toonlyO2oronlylight causes no change in the C 1sor O 1sspectra. In the C 1sspectra, the change in the dependence on the photon angle of incidence after exposure demonstrates that O attacks the polymer at the double bond in the vinyl group thereby altering the extended conjugation of the polymer. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116298

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report laser excited fluorescence in high purity synthetic diamond anvil to pressures of 370 GPa in a diamond anvil cell device. The nitrogen impurity level in this diamond is extremely low, and it allows us to study the stress effects on the optical transitions in diamond without interference from impurities. Pressure in the diamond anvil cell was measured by x‐ray diffraction using the platinum standard. Pressure dependence of the fluorescence peak was measured between 270 and 370 GPa in the visible spectral range. The variation of excitation laser wavelength shows clear cutoff in the excitation threshold in the 514–633 nm range at 370 GPa. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116299

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The losses of polycrystalline silicon (polySi) waveguides clad by SiO2are measured by the cutback technique. We report losses of 34 dB/cm at a wavelength of 1.55 &mgr;m in waveguides fabricated from chemical mechanical polished polySi deposited at 625 °C. These losses are two orders of magnitude lower than reported absorption measurements for polySi. Waveguides fabricated from unpolished polySi deposited at 625 °C exhibit losses of 77 dB/cm. We find good agreement between calculated and measured losses due to surface scattering. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116300

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We demonstrate all‐optical switching using the cascaded second order nonlinearity in a fully integrated, asymmetric Mach Zehnder interferometer implemented in lithium niobate channel waveguides. We obtained an 8:1 switching ratio. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116301

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A complete process compatible with conventional Si technology has been developed in order to produce a bipolar light‐emitting device. This device consists of a layer of light‐emitting porous silicon annealed at high temperature (800–900 °C) sandwiched between ap‐type Si wafer and a highly doped (n+) polycrystalline Si film. The properties of the electroluminescence (EL) strongly depend on the annealing conditions. Under direct bias, EL is detected at voltages of ∼2 V and current densitiesJ∼1 mA/cm2. The maximum EL intensity is 1 mW/cm2and the EL can be modulated by a square wave current pulse with frequencies &ngr;≥1 MHz. No degradation has been observed during 1 month of pulsed operation. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116302

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report a theoretical investigation of carrier trapping in GaAs v‐groove quantum wire structures. Our results show that trapping is fast in wires confined by AlGaAs alloy barriers where the growth process creates a Ga‐rich vertical quantum well at the center of the v‐groove: this acts as a highly effective scattering channel into quantum wires states. The results indicate that with suitable growth engineering, high‐efficiency quantum wire structures can be obtained. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.116303

出版商:AIP    

年代:1996

数据来源: AIP