摘要:

Intracavity nearly degenerate four‐wave mixing has been used together with transmission measurements to evidence the important role played by Auger recombination in the relaxation rate of electron‐hole pairs in semiconductor‐doped glasses pumped by high laser intensities. Results show a shortening by a factor of 100 of the recombination carrier lifetime when the laser intensity is near damage threshold.

ISSN:0003-6951    

DOI:10.1063/1.97746

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

GaAs/AlGaAs transverse junction stripe lasers with a distributed feedback structure were fabricated. The cw threshold current was 27 mA at 20 °C. The laser operated in a pure single longitudinal mode at the wavelength of 867 nm.

ISSN:0003-6951    

DOI:10.1063/1.97747

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The refractive index in a traveling‐wave semiconductor waveguide amplifier changes with light injection at intensities close to the saturation intensity due to light‐induced changes in the carrier density. The saturation‐induced optical switching in an active directional coupler switch based on this effect is investigated. The system can switch from a cross state at a low input power to a bar state at a high input power. This device may be used as a power‐limiting directional coupler switch with gain in a local area network.

ISSN:0003-6951    

DOI:10.1063/1.97748

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the fabrication and the characterization of low‐loss, single‐mode GaAs/AlGaAs ridge waveguides. The waveguides were grown by organometallic vapor phase epitaxy and were characterized at 1.52 &mgr;m wavelength. Their propagation losses were evaluated by measuring the finesse of the Fabry–Perot waveguide resonators formed by cleaving two opposite ends of these waveguides. Losses as low as 0.15 dB/cm were measured for single‐mode waveguides, which is the lowest value reported to date for single‐mode semiconductor waveguides. Such low‐loss waveguides should be useful in guided‐wave components for integrated optoelectronics.

ISSN:0003-6951    

DOI:10.1063/1.97749

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the intensity modulation of an optical carrier at frequencies as high as 40 GHz using a Ti:LiNbO3optical waveguide switch. The device is shown to exhibit a small‐signal electrical 3 dB bandwidth of >22 GHz and −8 dB response at 40 GHz. A high‐speed self‐electro‐optic‐sampling arrangement based on a mode‐locked injection laser is used to observe the modulation in the time domain.

ISSN:0003-6951    

DOI:10.1063/1.97750

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

High efficiency AlGaAs laser structures with graded index optical confinement regions and a single GaAs quantum well active region have been prepared using organometallic vapor phase epitaxy. The optimum quantum well thickness was determined to be near 50 A˚ where low internal losses are realized and the resulting threshold current densities were as low as 175 A/cm2on single ended devices with a high reflectivity coating on the rear facet. The high injected carrier levels which are associated with thin quantum well structures lead to a severe degradation in device performance if the gain required to reach lasing threshold becomes too large. If the device length, the facet reflectivities, and the operating temperature were chosen to prevent the injected carrier concentrations in the quantum well from reaching a level coincident with the onset of nonradiative carrier loss mechanisms, single ended power efficiencies exceeded 55% for room‐temperature, cw operation at 840 nm.

ISSN:0003-6951    

DOI:10.1063/1.97751

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The first buried heterostructure laser diodes fabricated by laser‐assisted disordering, a direct‐write process, are described. In laser‐assisted disordering a focused laser beam is scanned across the AlGaAs‐GaAs heterostructure material to induce local melting and thereby incorporate Si from an encapsulation layer into the regrown crystal. A subsequent thermal anneal (850 °C, 0.7 h) is used to diffuse the Si deeper into the sample to enlarge the disordered region. This combination of patterned crystal regrowth and impurity‐induced disordering is used to fabricate quantum well devices with lasing threshold currents as low as 6 mA (pulsed) and 8 mA (continuous). These devices have a narrow 4.5‐&mgr;m‐wide waveguide region and operate with a single longitudinal and spatial mode. They are the first optoelectronic devices fabricated with a direct‐write laser‐assisted process.

ISSN:0003-6951    

DOI:10.1063/1.97752

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We report the first use of chemically assisted ion beam etching to form laser mirrors on GaAlAs graded index separate confinement single quantum well heterostructures grown by metalorganic chemical vapor deposition. Over 80 mW cw optical power is obtained from the etched facet of uncoated 300‐&mgr;m‐long, etched/cleaved 60 &mgr;m stripe devices mountedpside up, and catastrophic failure occurs at a cw power as high as 205 mW. Differential quantum efficiencies for light emitted from the etched facet are 32% pulsed (27% cw) and the threshold current is 145 mA pulsed (150 mA cw).

ISSN:0003-6951    

DOI:10.1063/1.97753

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have fabricated multiple layer ZnO acoustic transducers for highly efficient sound wave generation at millimeter‐wave frequencies. The transducers consist of half‐wave‐thick layers of ZnO with alternating crystal structure. The two‐way untuned conversion loss values were 27 dB near 29 GHz and 50 dB at 96 GHz measured at liquid nitrogen temperatures.

ISSN:0003-6951    

DOI:10.1063/1.97754

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We have studied the influence of the bias potential on argon incorporation and bubble formation in sputtered thin films ofa‐Nb3Ge. Above 100 V bias bubbles are observed directly by transmission electron microscopy and indirectly by abrupt changes in the electronic properties. The influence of the sputter parameters on argon incorporation at 0 V bias is also investigated.

ISSN:0003-6951    

DOI:10.1063/1.97755

出版商:AIP    

年代:1987

数据来源: AIP