摘要:

A novel method was developed to fabricate corrugation for a &lgr;/4‐shifted distributed feedback (DFB) laser. Mechanically ruled grating patterns were transferred photolithographically to the surface of an InP substrate. The resultant &lgr;/4‐shifted DFB laser operated in a single longitudinal mode at the Bragg wavelength.

ISSN:0003-6951    

DOI:10.1063/1.101882

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Timing sychronization between a colliding‐pulse mode‐locked dye laser and a gain‐switched Fabry–Perot‐type AlGaAs laser diode has been achieved with less than 40 fs of relative timing jitter by using a pulsed optical phase lock loop. The relative timing jitter was measured using the error voltage of the feedback loop which has a 5 kHz bandwidth. This technique of measuring the relative timing jitter is accurate since the frequencies of all the timing fluctuations fall within the loop bandwidth. The novel element in the implementation of the pulsed optical phase lock loop is the time delay discriminator which is based on a cross correlation between the two pulse trains. Under locked conditions, the output of the cross correlator operates quiescently about a point of nonzero temporal slope.

ISSN:0003-6951    

DOI:10.1063/1.101883

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A theoretical description of the ultraviolet laser etching process is developed. The threshold for laser ablation is reached when the density of absorbed photons is approximately equal to the density of chromophores in the material. Saturation of the absorption coefficient, absorption by the plume of ablated products, and multiphoton effects are considered. Agreement with all available experimental etch data, including femtosecond ultraviolet laser ablation, is found. The description is based on an analysis of the radiation transport at high intensities and is independent of the question as to whether ultraviolet laser ablation is photochemical or thermal.

ISSN:0003-6951    

DOI:10.1063/1.101884

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We have achieved room‐temperature pulsed and cw lasing at 980 nm in an optically pumped vertical cavity structure grown by molecular beam epitaxy containing only a single quantum well (SQW) of In0.2Ga0.8As. Limited gain due to the extremely short active material length of 80 A˚ implies that losses due to absorption, scattering, and mirror transmission are extremely low. Using 10 ps pump pulses at 860 or 880 nm, the estimated energy density absorbed in the spacer was ∼12 fJ/&mgr;m2at threshold, indicating a carrier density approximately four times that required for transparency. Continuous wave pumping yielded an estimated threshold absorbed intensity of ∼7 &mgr;W/&mgr;m2.

ISSN:0003-6951    

DOI:10.1063/1.101885

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

By using the resonance property of modal fields, we derive leaky‐wave modes supported by nonlinear layered media of the Kerr type and apply the results to obtain the beam field emitted by an output prism coupler containing such a nonlinear layer.

ISSN:0003-6951    

DOI:10.1063/1.101886

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Pb1−xSrxS/PbS double‐heterostructure stripe contact lasers were prepared for the first time using a hot‐wall expitaxy technique. The laser operated up to 245 K pulsed (2.97 &mgr;m) and 174 K cw, which are the highest operating temperatures ever reported for any semiconductor diode lasers operating around 3 &mgr;m. In this letter preparation and properties of the Pb1−xSrxS lasers are presented.

ISSN:0003-6951    

DOI:10.1063/1.101887

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Rare‐earth element erbium implanted into silicon was studied by photoluminescence and Rutherford backscattering analysis. Two sets of luminescent bands related to the weakly crystal field split spin‐orbit levels4I13/2→4I15/2of Er 3+(4f 11) at different lattice sites having different symmetries were observed.

ISSN:0003-6951    

DOI:10.1063/1.101888

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A transient line source, either mechanical or electrical, on the surface of a piezoelectric medium will excite electromagnetic acoustic (EMAC) head waves between quasi‐electromagnetic surface disturbances and quasi‐acoustic waves. EMAC head waves are acoustic in nature, with plane fronts practically parallel to the surface and traveling at acoustic speeds. One such plane wave front is observed experimentally in a thick lead titanate‐zirconate plate in accordance with theory.

ISSN:0003-6951    

DOI:10.1063/1.102426

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A reliable means of removing surface layers of diamond is of significant importance for microelectronics as well as for other applications such as polishing of the diamond surface. Preliminary studies using reactive ion etching with O2and H2showed etching rates of the order of 560 A˚/min for thin carbon films and 350 A˚/min for natural type II‐A diamonds using 300 eV oxygen ions. Addition of a substantial percentage of Ar to oxygen in the reaction chamber did not affect the etching rate.

ISSN:0003-6951    

DOI:10.1063/1.101890

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A force microscope is described that can be used for high‐resolution surface profiling and for observing magnetic domains. The microscope uses a Michelson interferometer to sense the vibration of a cantilever. The interferometer contains some straightforward processing to eliminate laser intensity noise. Some measuring results are presented that illustrate the performance of the microscope.

ISSN:0003-6951    

DOI:10.1063/1.101891

出版商:AIP    

年代:1989

数据来源: AIP