摘要:

We demonstrate a laser amplifier photonic integrated circuit having 370‐mW cw output power emitted in a single transverse mode a 1.48 &mgr;m wavelength, suitable for pumping erbium‐doped fiber amplifiers.

ISSN:0003-6951    

DOI:10.1063/1.106063

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have formed PbTiO3thin films on (100) SrTiO3substrates at a temperature of 350 °C using an ArF excimer laser ablation technique. Until now, PbTiO3films have not been formed at temperatures lower than 500 °C using other thin‐film techniques. The important points in the present study are the laser excitation of the substrate during the film growth and the lattice matching between the film and the substrate. The film deposited on the SrTiO3substrate shows preferential orientation of thec‐axis perpendicular to the substrate surface.

ISSN:0003-6951    

DOI:10.1063/1.106038

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The optical performance of Li‐based variable transmission electrochromic windows incorporating tin‐doped indium oxide thin‐film counterelectrodes have been measured. The electrolyte used was 1M LiClO4dissolved in dry propylene carbonate, the active device area was approximately 10 cm2and the devices were driven galvanostatically with a current density of 100 or 200 &mgr;A/cm2. Significant and reversible transmission modulation could be achieved in these devices. The characteristics of the WO3electrochromic electrode and the tin‐doped indium oxide counterelectrode used were found to have a marked effect on the optical response of the device. The plasma wavelength of the tin‐doped indium oxide counterelectrode was found to be a critical parameter.  

ISSN:0003-6951    

DOI:10.1063/1.106014

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The linewidth enhancement factor &agr; has been determined in GaInSbAs/GaSb lasers emitting near 1.8 &mgr;m (2 &mgr;m at RT) from the spontaneous emission spectra below threshold. For type‐I lasers, where ap‐njunction was located at the GaAlSbAs/GaSb heteroboundary, the measured &agr; is 3.1 at the lasing wavelength at 82 K. In type‐II lasers with thep‐GaSb/GaInSbAs heterojunction &agr; was estimated to be at least 2 times lower, that can be attributed to the formation of a quantum well structure at this heteroboundary under lasing conditions.

ISSN:0003-6951    

DOI:10.1063/1.106015

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An optical phase shifter with current injection has been demonstrated in a GaAs/AlGaAs multiple quantum well (MQW) single mode waveguide. Phase shifts at different wavelengths have been measured and compared with the theory in L. Banyai and S. W. Koch, Z. Physik B63, 283 (1986). A 3&pgr; phase shift has been achieved in a 400‐&mgr;m‐long waveguide with almost no material absorption.

ISSN:0003-6951    

DOI:10.1063/1.106016

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on the preliminary experimental demonstration of a multiple‐quantum‐well waveguide grating element. Due to optical nonlinearities in a multiple‐quantum‐well layer incorporated into the structure, the out‐coupling angle of the grating is varied by the intensity of light in a guided mode. Experiments with GaAs‐based planar as well as rib waveguide samples confirmed theoretical predictions. Changes in the coupling angle obtained are on the order of minutes. The demonstrated principle can be employed in fine tuning of the coupling angle, fine focusing of the output beam, or as a nonlinear beam‐steering method for dispersion measurements.

ISSN:0003-6951    

DOI:10.1063/1.106017

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An all fiber, widely tunable, single‐frequency, erbium‐doped fiber ring laser was constructed with a threshold pump power as low as 10 mW. Tuning over more than 30 nm was obtained by applying 0 to 17 dc V to an intracavity fiber Fabry–Perot filter. Threshold pump power versus wavelength data showed low variation over the tuning range. Mode hopping suppression with a tandem fiber Fabry–Perot filter is proposed and demonstrated. Stable single‐frequency operation was demonstrated with side mode suppression higher than 35 dB.

ISSN:0003-6951    

DOI:10.1063/1.106018

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A phase‐shifting method to directly measure the amplitude and phase distribution of specimen in an electron holographic microscope without the introduction of large number of carrier fringes is proposed. The initial phase of electron holograms is shifted by tilting the incident electron beam with a digital voltage/current supply. Several holograms of a specimen with properly different phase shifts are recorded digitally and used to calculate the amplitude and phase distributions of the specimen. Experimental result of observing the phase distribution of a cubic MgO crystal is shown.

ISSN:0003-6951    

DOI:10.1063/1.106019

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrated the first successful growth of 1.5 &mgr;m strained‐layer InGaAs/InGaAsP multi‐quantum‐well (MQW) distributed feedback (DFB) lasers by chemical beam epitaxy (CBE). In these DFB wafers, a quaternary grating is placed at the bottom of the MQW stack with an InP spacer layer. Studies by transmission electron microscopy show that defect‐free InP regrowth was achieved with no mass transport needed over the grating corrugations before regrowth. With CBE regrowth the shapes of the gratings were well preserved. The InP overlayer also very effectively smoothed out the quaternary surface corrugations resulting in very flat MQW structures. Buried‐heterostructure 6‐QW DFB lasers (250 &mgr;m long and as‐cleaved) operated at 1.55 &mgr;m with cw threshold currents 10–15 mA and slope efficiencies up to 0.35 mW/mA (both facets). Side‐mode suppression ratios (SMSR) as high as 49 dB was obtained. The laser operated in the same DFB mode with SMSR staying above 40 dB from threshold and throughout the entire current range even at high temperatures (70 °C checked).

ISSN:0003-6951    

DOI:10.1063/1.106020

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The first experimental demonstration of the physical mechanism underlying multi‐electron‐beam Cherenkov free‐electron lasers has been carried out. Electron beams of a total beam current of 280 A at 500 kV were introduced into a multi‐dielectric cavity and stimulated Cherenkov radiation of 1.7 MW at 33.4 GHz was generated. The interaction efficiency was about 1.2%.

ISSN:0003-6951    

DOI:10.1063/1.106021

出版商:AIP    

年代:1991

数据来源: AIP