摘要:

We present a time-multiplexed interferometer based on Faraday mirrors, and apply it to quantum key distribution. The interfering pulses follow exactly the same spatial path, ensuring very high stability and self balancing. The use of Faraday mirrors compensates automatically any birefringence effects and polarization dependent losses in the transmitting fiber. First experimental results show a fringe visibility of 0.9984 for a 23-km-long interferometer, based on installed telecom fibers. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118224

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A consistent method to characterize the temperature dependence of bulk InGaAsP semiconductor laser diodes is presented. Independent measurements of the gain and spontaneous emission spectra are conducted, and the spectra are calibrated using their fundamental relationship. This procedure will provide a unique approach to extract precise values for laser diode parameters such as quasi-Fermi level separation, peak modal gain, and total loss. The radiative and nonradiative current densities can then be calculated as a function of temperature and injection current. By comparing the measured data with a theoretical model, the carrier density is calculated. Important phenomena contributing to the strong temperature dependence of long-wavelength bulk InGaAsP/InP lasers are highlighted. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118225

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Results are presented on planar microcavity light emitting diodes with different device diameters. A record external quantum efficiency of 20&percent; is achieved for a 1.5 mm light emitting diode. The strong dependence of the quantum efficiency on current density and device size are compared with theoretical results. A good correspondence is obtained when spectral broadening and photon recycling are taken into account. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118226

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A GaInAsSb/AlGaAsSb multiple-quantum-well diode laser structure consisting of Al0.6Ga0.4As0.05Sb0.95cladding layers, Al0.3Ga0.7As0.02Sb0.98confining layers, and four 15-nm-thick Ga0.87In0.13As0.12Sb0.88quantum wells with 20-nm-thick Al0.3Ga0.7As0.02Sb0.98barrier layers was grown by organometallic vapor phase epitaxy. These lasers, emitting at 2.1&mgr;m, have exhibited pulsed threshold current densities as low as 1.2 kA/cm2. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118227

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The optic impedanceZof a medium for the propagation of electromagnetic waves is deduced from the definition of wave impedance. A new optical parameterZocalled “specific optic impedance” is defined. The temperature dependence ofZois examined and an exponential relationship between specific optic impedances at two different temperatures has been derived. The validity of the new relationship is established using the published data on ethyl acetate, cyclohexane, benzene, and a binary mixture of polyvinyl pyrrolidone inN,N-dimethyl formamide solutions from the literature. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118228

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Comparing the results of the quantum well laser diode simulator Minilase-II with modulation responses measured at the University of California, Santa Barbara, we show that electron and polar optical phonons are rapidly heated above equilibrium in conventional injection lasers. This heating essentially follows and counteracts the modulation of the carrier density, leading to degradation of the dynamic laser response even for relatively small changes in carrier temperature. With this in mind, we speculate about the use of tunneling injection to avoid the hot quantum carrier effects intrinsic to conventional injection lasers. ©1997 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.118229

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

GaN epilayers have been grown on basal plane (0001) sapphire by plasma-assisted molecular beam epitaxy (MBE) with a novel, inductively coupled nitrogen plasma source. Films grown at 700 °C generate stimulated emission at 300 K when optically pumped in vertical geometry with ∼3.5 eV (&lgr;=355nm) photons. The extrapolated pump power threshold is ∼3.6MW cm−2which corresponds to an absorbed value of 700kW cm−2and a peak carrier number density of∼4×1019 cm−3. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118230

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Spectral splitting due to the exciton response of a three InGaAs quantum well active region placed in various high contrast semiconductor microcavities is observed near room temperature. The planar microcavities consist of one-wavelength thick cavity spacers surrounded by AlGaAs/GaAs along with high contrast distributed Bragg reflectors formed fromAlxOy/GaAsand MgF/ZnSe. Microcavities having different loss rates are characterized over a range of temperatures using reflectance, transmission, and photoluminescence. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118231

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The transient response of theZ-scan signal&Dgr;T(t)was used to investigate the nonlinearity of ion doped solids.n2measurements in ruby and alexandrite were performed using anAr+laser. We observed that the nonlinearity response time &tgr; decreases with the laser intensity as&tgr;−1=&tgr;0−1(1+I/Is), where&tgr;0is the excited state lifetime andIsthe transition saturation intensity. So, by measuring the transient response at different laser intensities, we were able to determine not only the nonlinear complex refractive indexn2but also&tgr;0andIsforCr+3in ruby and in the two alexandrite sites. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118232

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Two-dimensional image transfer with frequency upconversion from the pump to the anti-Stokes beam has been realized using polarization coupling in rotational Raman scattering. With two pump beams of counter-rotating circular polarization from aQ-switched Nd:YAG laser, images carried in either pump can be transferred to the anti-Stokes beam through pump-phonon coupling in a hydrogen cell. Image addition has also been demonstrated when different objects are inserted simultaneously in two pump beams. The potential for imaging through scattering media with this technique is discussed. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118233

出版商:AIP    

年代:1997

数据来源: AIP