摘要:

Optical nonlinearity of a sputtered SiO2film containing CdSe microcrystallites with an average diameter of 15 A˚ is measured by degenerate four‐wave mixing (DFWM) experiments. An effective nonlinear cross section &sgr;effof 1.4×10−16cm2is obtained. The DFWM signal as a function of the probe delay time shows biexponential behavior with a fast decay time of 10 ps and a slow decay time of 60 ps, which give fast and slow carrier recombination times as 20 ps and 120 ps. The third‐order susceptibility ‖&khgr;(3)‖ is estimated to be 1.3×10−8esu. The photodarkening and laser annealing effects which are serious problems for device applications are not observed.

ISSN:0003-6951    

DOI:10.1063/1.104176

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We demonstrate a novel waveguide structure for realization of integrated optics with compact waveguide bends (radii≊1 mm), low propagation loss (0.45 dB/cm), and large guide dimensions (5 &mgr;m width) to facilitate input coupling. Experimental results using single‐mode GaAs/AlGaAs heterostructure guides at 1.52 &mgr;m wavelength are presented.

ISSN:0003-6951    

DOI:10.1063/1.104112

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An all‐optical logic gate has been demonstrated in a nonlinear organic e´talon using femtosecond laser pulses. The logic gate consists of a guest‐host organic thin film, 7‐[4‐[(4‐hexyloxyphenyl)azo](naphthyl)azo‐(2,3‐dihydro‐1,3‐dimethyl‐2‐octyl)] perimidine doped in poly(methyl methacrylate), sandwiched between two highly reflective mirrors. It shows a subpicosecond switch‐on time and a switch‐off or recovery time that has a fast, &bartil;4 ps component and slower components. A maximum contrast ratio of &bartil;2 between the switch‐on and switch‐off states of the optical gate was obtained. The nonlinear index of refraction is also measured from this Fabry–Perot interferometer to be &Dgr;n=0.005.

ISSN:0003-6951    

DOI:10.1063/1.103857

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The lasing wavelength of a strained‐layer InGaAs/GaAs single quantum well laser has been found to depend strongly on the cavity length. The relationship between the lasing wavelength and the cavity length was established experimentally and a cavity length tuning mechanism for a quantum well laser is thus made possible.

ISSN:0003-6951    

DOI:10.1063/1.103858

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The time development of a photorefractive grating created by intersecting 30 ps (532 nm) beams in a well‐characterized Bi12SiO20crystal (in a static field around 1 kV/cm) unambiguously reveals the mobility of photoexcited electrons to be 0.24±0.07 cm2/V s through what is essentially a ‘‘time‐of‐flight’’ measurement.

ISSN:0003-6951    

DOI:10.1063/1.103859

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Room‐temperature laser‐induced voltages were observed in unsupported, polycrystalline wafers of YBa2Cu3O7−xin the absence of a transport current. Peak voltages of ∼1 V were detected in response to 40 mJ pulses of 532 nm light. The rise and fall times for the signals were detector limited. The half widths of the signals were instrument response limited (laser pulsed limited for a 10 ns laser pulse and digitizer limited for a 30 ps laser pulse). At fixed pulse energy, the induced peak voltage scales as the sine of the angle of incidence of the laser beam and is nulled at normal incidence. The magnitude of the signal as a function of sample thickness, preparation, and laser excitation wavelength is discussed.

ISSN:0003-6951    

DOI:10.1063/1.103860

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new tool, a lasing phase diagram, for understanding semiconductor surface‐emitting injection lasers has been synthesized. The diagram shows how to design laser resonators which have the lowest possible threshold currents and highest operating efficiencies. To create this diagram, the rate equations describing the photon and electron‐hole densities in the laser are solved for the steady‐state conditions. The solutions are compactly summarized on a single lasing phase diagram which shows the lasing threshold current and power efficiency contours as functions of two structural parameters (mirror loss and number of quantum wells) in a two‐dimensional plane. The plane is separated into three regions corresponding to lasing, marginal lasing, and nonlasing structures. The diagram predicts that, in the high reflectance limit, the threshold current is independent of mirror loss and scales directly with the number of quantum wells in the active region. The phase diagram has been successfully used to understand the lasing characteristics of many different laser structures recently reported.

ISSN:0003-6951    

DOI:10.1063/1.103861

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report on studies of optically pumped laser action in (Zn,Cd)Se/ZnSe multiple quantum well structures prepared by molecular beam epitaxy on lattice‐matched bulk (Ga,In)As substrates. Room‐temperature lasing under pulsed excitation with threshold pump intensity atI≊500 kW/cm2has been achieved, together with high repetition ‘‘quasi‐continuous’’ mode operation at temperatures so far up to 100 K.

ISSN:0003-6951    

DOI:10.1063/1.103862

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We describe an absorption spectroscopy experiment at 194 nm on Hg+, ground‐state atomic mercury ions, and at visible wavelengths on Hg*, excited 63Pomercury atoms in Hg‐Ar discharges. This experiment is used to map the absolute density of Hg+and Hg* in the cathode region of Hg‐Ar discharge lamps operated in the hot‐cathode mode.

ISSN:0003-6951    

DOI:10.1063/1.103863

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Using a system coupling molecular beam deposition, scanning tunneling microscopy, and Auger spectroscopy in a connected ultrahigh‐vacuum environment, we have observed the initial stages of GaAs growth on vicinal Si(100), including As termination, ordered Ga overlayers, and subsequent competition between two‐ and three‐dimensional structures.

ISSN:0003-6951    

DOI:10.1063/1.103864

出版商:AIP    

年代:1990

数据来源: AIP