摘要:

We report the observation of amplified spontaneous emission in silica‐based single‐mode optical fibers doped with Tm3+. Frequency upconverted emission was observed in a number of visible and near‐infrared lines after pumping by 1064 nm radiation. The upconversion process is induced via the nonlinear absorption of the infrared beam and enhanced by stimulated Raman scattering in the fiber, leading to amplified spontaneous emission in the blue (∼473 nm) region.

ISSN:0003-6951    

DOI:10.1063/1.103924

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have demonstrated high average power output devices in both one‐dimensional (1‐D) and two‐dimensional (2‐D) arrays of laser diodes using efficient edge emitting cleaved bars and silicon microchannel coolers. These packages are based on the rack and stack architecture. For the 1‐D array a cw optical power output of 22.2 W was obtained with 20% electrical to optical conversion efficiency. For the 2‐D array an average optical power density of greater than 100 W/cm2was obtained at an efficiency of 25%.

ISSN:0003-6951    

DOI:10.1063/1.103925

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Fission‐fragment‐excited lasing is reported for the 3p’(1/2)0–3s’(1/2)01neon transition (&lgr;=585.3 nm) in mixtures of He/Ne/Ar. The laser power efficiency peaks at a He/Ne/Ar ratio of approximately 50/2/1 for a laser cell pressure of 1.9 atmospheres. Laser parameters for pump rates from 70 to 1200 W/cm3are presented for three cavity configurations.

ISSN:0003-6951    

DOI:10.1063/1.103926

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Emission spectrum of the laser‐induced plasma plume is obtained during KrF excimer laser ablation of graphite in argon and hydrogen gas mixture for deposition of diamond‐like films. Bands of C2and CN molecules dominate the spectrum while weak CI, CII, and H&agr;lines are also observed. From the emission intensities, molecular vibrational temperature is calculated to be (12–15)×103K, and concentrations are estimated to be N(C2)=5×1014cm−3and N(CN)=2×1014cm−3.

ISSN:0003-6951    

DOI:10.1063/1.103927

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using a hybrid optical/electronic technique, an external‐cavity diode laser was frequency stabilized with respect to the sub‐Doppler spectrum of cesium vapor. Laser linewidths of 65 kHz and frequency stabilities of ±10 kHz were obtained.

ISSN:0003-6951    

DOI:10.1063/1.103928

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A survey of graded‐index separate confinement multiple quantum well distributed feedback lasers comparing the effects of strain in the quantum well upon threshold, output power, and linewidth is reported. Lasers with either compressive or tensile strained quantum wells and a long cavity length (890 &mgr;m) show lower threshold current (10–20 mA) as well as lower linewdith power product than lasers with unstrained quantum wells and have a comparable minimum linewidth to the unstrained quantum well lasers. A minimum linewidth as narrow as 900 and 440 kHz for compressive strain and unstrained quantum well lasers, respectively, was obtained at output power of 30 mW. Single longitudinal mode operation with a maximum output power over 80 mW was observed in all the structures.

ISSN:0003-6951    

DOI:10.1063/1.103929

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Polycrystalline diamond films deposited by the microwave plasma chemical vapor deposition (CVD) technique onto quartz substrates have been irradiated with 100 keV C and 320 keV Xe ions at room temperature and at 200 °C. The dose dependence of the electrical conductivity measuredinsituexhibited complicated, nonmonotonic behavior. High doses were found to induce an increase of up to ten orders of magnitude in the electrical conductivity of the film. The dose dependence of the conductivity for the CVD films was found to be very similar to that measured for natural, type IIa, single‐crystal diamonds irradiated under identical conditions. This result suggests that the conduction mechanism in ion beam irradiated polycrystalline CVD diamond films is not dominated by grain boundaries and graphitic impurities as one might have expected, but rather is determined by the intrinsic properties of diamond itself.

ISSN:0003-6951    

DOI:10.1063/1.103931

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We show here that the implants of oxygen, a basically nondopant impurity, after adequate high‐temperature annealings (for example, 750 °C, 1 h furnace anneal) lead to a significant interdiffusion of group III atoms in molecular beam epitaxy grown In0.53Ga0.47As‐In0.52Al0.48As multiquantum wells (MQWs). Both photoluminescence and Auger electron spectroscopy measurements (coupled to Ar+ion etching) have been employed to monitor disordering in MQWs implanted with oxygen (5×1013to 5×1014ions cm−2) and subsequently annealed using either rapid thermal anneals or long duration furnace anneals. The role of oxygen to enhance group III atom (Al, Ga, and In) interdiffusion is unambiguously established and a tentative explanation based on a possible migration of oxygen in these MQWs is proposed and dissussed.

ISSN:0003-6951    

DOI:10.1063/1.103932

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Oxide layers have been formed on (110) and (100) GaAs wafers by exposure to a high kinetic energy beam of atomic O and characterized using x‐ray photoemission spectroscopy (with Ar+ion sputter profiling) and Raman spectroscopy. Photoemission shows the reacted layer, ∼500 A˚ thick, to be uniform in composition and fully oxidized. Raman spectroscopy shows that the substrate is not appreciably disordered during oxidation and in some cases no free‐elemental As is present at the oxide‐substrate interface at a detectable level.

ISSN:0003-6951    

DOI:10.1063/1.103933

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The hypersonic behavior of a vinylidene fluoride and trifluoroethylene (70/30 mol %) copolymer has been investigated by Brillouin scattering without using index matching liquid. Both the glass and ferroelectric transitions are clearly seen in the acoustic behavior. The home‐prepared sample has excellent optical properties and let us obtain sound attenuation information in the temperature range of 23–123 °C, which another investigator did not discuss because of the bad optical properties of the sample surface. Anomalies of sound attenuation near the transition point have been observed.

ISSN:0003-6951    

DOI:10.1063/1.103934

出版商:AIP    

年代:1990

数据来源: AIP