摘要:

We model the electron waveguide coupler as a four‐terminal device, by considering the scattering at the interaction region between the electron waveguides. Transmission and reflection coefficients are evaluated for a variety of system parameters. Periodic switching of the electron wave between the waveguides are observed. Complete electron transfer occurs at a transfer length as short as 400 A˚. This value is much smaller than that predicted by coupled‐mode theory and the device is thus experimentally realizable.

ISSN:0003-6951    

DOI:10.1063/1.106400

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Experimental measurements were made to demonstrate that the degree of beam steering in an injection‐locked laser diode array is related to the divergence of the master laser beam. For a collimated master laser beam the beam steering was suppressed. The injection‐locked laser diode array beam steers with the master laser wavelength because only a portion of the divergent master laser beam satisfies the round trip mode condition.

ISSN:0003-6951    

DOI:10.1063/1.105794

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present a demonstration of the electro‐optic tuning in a GaAs/AlGaAs quantum well vertical codirectional coupler filter. Tunable range over 2 nm was realized through the quantum‐confined Stark effect with a tuning rate of 0.28 nm/V2for transverse magnetic polarization. A filter bandwidth as narrow as 1.7 nm (full width at half‐maximum) at 830 nm with a coupling region length of 490 &mgr;m was obtained.

ISSN:0003-6951    

DOI:10.1063/1.105795

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

High performance InGaAsP/InP multiquantum well (MQW) buried heterostructure lasers emitting around 1.3 &mgr;m were prepared for the first time by chemical‐beam epitaxy. At 20 °C, continuous‐wave (cw) threshold currents were 5–8 mA and quantum efficiencies were 0.35–0.45 mW/mA for 250 &mgr;m long lasers having one facet ∼85% reflective coated. At 80 °C, the cw threshold currents remained low, 23 mA, quantum efficiency stayed high, 0.22 mW/mA, and output power of ∼10 mW was achieved. cw power output as high as 125 mW was achieved with 750 &mgr;m long lasers having AR–HR (∼5%–85%) coatings. Lasers with bulk active were also studied for comparison. Though they also have excellent device performance, in general, they are somewhat inferior to MQW lasers.

ISSN:0003-6951    

DOI:10.1063/1.105796

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A high‐power 1.55 &mgr;m large optical cavity (LOC) laser structure is successfully prepared for the first time by reasonably designing its configuration and by using a proper single step liquid phase epitaxy (LPE) so as to realize lasers with peak output power higher than 2 W per facet in pulsed operation at room temperature. The devices are also characterized by their lower threshold current ( Jth≤2.7 KA/cm2for broad area contact structure) and high‐temperature stability (T0≊130 K). At the same time they are of long‐lived operation and are an ideal source of light in this spectral region.

ISSN:0003-6951    

DOI:10.1063/1.105797

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The energy relaxation and the dephasing time constants of colored filter glass are measured as functions of temperature and the wavelength of the incident light by degenerate four‐wave mixing. To investigate the influence of the photodarkening effect on the relaxation time constants, fresh and photodarkened samples are measured. The two samples have almost the same dephasing time constants but their energy relaxation time constants are quite different.

ISSN:0003-6951    

DOI:10.1063/1.105798

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A new integrated optic matrix algebra processor architecture that utilizes guided‐wave multifrequency acoustooptic (AO) Bragg diffractions is proposed. The architecture is potentially capable of performing matrix‐vector multiplications faster than any AO architecture reported heretofore, and matrix‐matrix multiplications at rates comparable to the fastest bulk‐wave AO architecture. An integrated AO processor module has been realilzed in a Y‐cut LiNbO3substrate 1.0×10.0×28.0 mm3in size to demonstrate the multiplication of a 4×4 matrix with a 4‐element vector at the optical wavelength of 0.6328 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.105799

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The generation of a diffraction‐free Bessel beam from a beam that is originally Gaussian is accompanied by substantial power loss. We employed the technique of holographic intensity amplification to enhance the conversion from a Gaussian beam to a Bessel beam with conversion efficiency approaching 50%. In addition the maximum propagation distance was extended.

ISSN:0003-6951    

DOI:10.1063/1.105800

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A low power, high contrast optically addressed modulator, operating with normal incidence, has been fabricated. Optically controlled reflection modulation is achieved through optically induced absorption modulation in a periodically &dgr;‐doped InGaAs/GaAs multiple quantum well structure inserted in an integrated asymmetric Fabry–Perot resonator. A contrast ratio≳60:1 was measured using a spectrally matched low power InGaAs/GaAs quantum well laser to generate the write (control) signal. The insertion loss for the normally off modulator is 4.6 dB at the highest write signal power (30 mW) used. The device lends itself to the fabrication of arrays for optically addressed spatial light modulation.

ISSN:0003-6951    

DOI:10.1063/1.105805

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Particulate (or ‘‘dust’’) contamination of plasma materials processing discharges is known to reduce yields of the product and to perturb electron transport. Dust preferentially accumulates near the cathode sheath‐plasma boundary where energetic electrons accelerated in the cathode fall emanate into the negative glow. In this letter, we theoretically investigate the penetration of the electron flux generated in dc cathode falls through the particulate ‘‘barriers’’ formed by dust contamination. We find that at constant current densities, the plasma responds to the reduction in ionization rate coefficients caused by the particulates by increasing the electric field in the cathode fall. In doing so, the cathode fall voltage increases and cathode fall thickness decreases.

ISSN:0003-6951    

DOI:10.1063/1.105777

出版商:AIP    

年代:1991

数据来源: AIP