摘要:

A passive phase conjugate mirror based on four‐wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self‐starting by four‐wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported.

ISSN:0003-6951    

DOI:10.1063/1.93800

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have prepared and characterized for the first time a new current injection double‐heterostructure (DH) laser with GaxAlyIn1−x−yAs as the active layer and InP as the cladding layers operating at 1.5‐&mgr;m wavelength. In this new heterostructure, there is only one group V element involved in every layer. This eases the precise control of lattice matching during molecular beam epitaxial (MBE) growth. At the same time, it eliminates the use of Al0.48In0.52As, which is of lower quality than InP when grown by MBE, as the cladding layers. Broad‐area Fabry–Perot diodes of 380×200 &mgr;m have a threshold current density of ∼3.2 kA/cm2for active layer thickness of 0.25 &mgr;m. In the temperature range ∼15–50 °C, the threshold temperature dependence coefficientT0is typically ∼40 K. Above ∼50 °C,T0decreases to ∼25–35 K. The present laser also represents the first current injection DH laser emitting at 1.5 &mgr;m ever prepared by MBE. In the present experiment, As2instead of As4was also used for the first time in growing the GaxAlyIn1−x−yAs layers by MBE in order to improve their quality. This becomes particularly important as the substrate growth temperatures employed are relatively low, ≲625 °C.

ISSN:0003-6951    

DOI:10.1063/1.93801

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We report the first observation of forward degenerate four‐wave mixing (DFWM) in room‐temperature GaAs/GaAlAs multiple quantum well structures near the exciton resonances. In a sample 1.26 &mgr;m thick with sixty‐five 96‐A˚ GaAs quantum wells we observe ∼10−4diffraction efficiency with ∼30 W/cm2average intensity from a mode‐locked laser. We measure nonlinear absorption and DFWM spectra, and also a change in refractive index, per carrier pair/cm3, ofneh∼2×10−19cm3just below the heavy hole exciton peak. With 20‐ns carrier lifetime this corresponds to an effective nonlinear coefficient for cw beams of ‖n2‖&bartil;2×10−4cm2/W. This is appreciably larger than previous estimates and encouraging for room‐temperature all‐optical devices.

ISSN:0003-6951    

DOI:10.1063/1.93802

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A new method of evaluating the dependence on carrier density of the propagation constant of the excited mode of a semiconductor laser biased above threshold is applied to a single mode confined double heterostructure‐large optical cavity laser operated at 8‐mW dc. The method combines the measurements of the Fabry–Perot spectrum of the modulated laser, the relative modulation amplitudes of the coherent and short‐wavelength spontaneous powers and the phase difference between the two, and the dependence on dc current of the two emissions. The evaluation is independent of the model of the lasing state, the reduction of the raw data requiring only subthreshold relations between current, voltage, carrier density, and spectrum. The change of the index of refraction of the waveguide mode with the concentration of electron‐hole pairs in the recombination region is +1.8×10−22cm3. Striking inconsistencies among various published accounts indicate a need for critical examination of all such studies.

ISSN:0003-6951    

DOI:10.1063/1.93803

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We have discovered that laser beam deflection spectroscopy can be used for the absolute measurement of wave or particle beam attenuation in condensed matter. The concept has been experimentally evaluated by successfully measuring the absolute optical attenuation in a crystal of U3+:CaF2at 514 nm. A theoretical model that explains the experiment and characterizes the range of applicability of the method has been developed.

ISSN:0003-6951    

DOI:10.1063/1.93804

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Arrays of five InGaAsP buried‐cresent large‐optical‐cavity lasers operating at 1.3 &mgr;m are described. The monolithically integrated arrays have threshold as low as 60 mA, external quantum efficiencies &eegr;≊55%, and operate in the fundamental transverse mode up to 50 mW per facet at room temperature. Despite the very close center to center spacing of 8 &mgr;m, no electrical or optical interaction between lasers has been observed.

ISSN:0003-6951    

DOI:10.1063/1.93805

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

100‐mW room‐temperature cw laser operation at 7300 A˚ has been achieved in a Ga1−xAlxAs (x∼0.22), ∼300 A˚ thick, single quantum well double heterostructure diode grown by organometallic vapor phase epitaxy. The proton‐delineated stripe contact is 6 &mgr;m wide, and the front and rear laser facets are coated for antireflection and high reflection respectively. The cw threshold current is 86 mA for a 250‐&mgr;m‐long device, and linear output power versus current characteristics are observed up to 100 mW with an external differential quantum efficiency of 1 W/A (59%). cw output power exceeds 13 mW at 100 °C. Between 25–55 °C, the pulsed threshold current varies exponentially with temperatureTas exp(T/T0), whereT0∼187 K.

ISSN:0003-6951    

DOI:10.1063/1.93806

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Surface acoustic wave properties of Ba2NaNb5O15crystals are investigated in terms of electromechanical coupling coefficientk2and frequency temperature coefficients. AX‐rotated cut and aY‐rotated cut are selected for their fair coupling. Experimental verifications on a Union Carbide Ba2NaNb5O15crystal proved excellent agreement for the coupling (1.2%) and markedly better results than computed for the frequency‐temperature coefficient. The best value is measured to be as low as 1.5 ppm/K for ⟨101⟩ cut, (1¯01) propagation.

ISSN:0003-6951    

DOI:10.1063/1.93799

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The first results of experiments using plasma opening switches for inductive energy storage are described. The switch has been shown to conduct up to 200‐kA current for ∼50 ns then to open in <10 ns, transferring the current to an electron beam load. Inductive energy storage, pulse compression, and power multiplication are demonstrated. A simple model explaining the switch operation is presented.

ISSN:0003-6951    

DOI:10.1063/1.93807

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Time and radially resolved vacuum‐ultraviolet spectra from an argon gas‐puffZpinch have been obtained using a grazing incidence spectrometer with gated microchannel plates curved to the Rowland circle. Most of the 50–300‐A˚ radiation is emitted from a dense core (r≊0.4 mm,ne≳1019cm−3,Te≊150 eV) which forms when the plasma assembles on the axis.

ISSN:0003-6951    

DOI:10.1063/1.93808

出版商:AIP    

年代:1983

数据来源: AIP