摘要:

An HF laser was used to directly pump various isotopic forms of CO2. Intense laser emission was observed on numerous lines in the 4.3‐, 10.6‐, and 17‐&mgr;m regions. All observed 4.3‐ and 17‐&mgr;m CO2laser emission lines were assigned. The pressure dependence of lasing spectra and laser pulse temporal features were examined.

ISSN:0003-6951    

DOI:10.1063/1.89054

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

High‐efficiency blazed grating couplers have been successfully realized by using an ion etching technique. We observed that a guided wave was radiated as the leaky wave which appears selectively either above or below the grating depending on the direction of the propagation of the guided wave. The coupling efficiency from the guided wave into one of the leaky waves was about 97% at the blaze angle of 30°.

ISSN:0003-6951    

DOI:10.1063/1.89055

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We suggest that high‐efficiency frequency upconversion and downconversion can be achieved by four‐wave mixing in media containing infrared‐active molecules. The high‐efficiency results from the relatively large vibrational matrix elements and small energy denominators. Numerical calculations are presented for generation of radiation at 2&ohgr;1+&ohgr;2in HCl where 2&ohgr;1is tuned to an electric‐dipole‐forbidden vibration‐rotation transition. We also present some general considerations for four‐wave mixing in molecular media.

ISSN:0003-6951    

DOI:10.1063/1.89056

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Distributed feedback laser operation is demonstrated in stripe‐geometry Pb1−xSnxTe double heterostructures grown by molecular‐beam epitaxy. The grating of 1.1 &mgr;m periodicity operates in first order near 745 cm−1(13.4 &mgr;m) under pulsed conditions in a limited range of heat‐sink temperatuers (∼30–65 K) where both gain and the Bragg reflection condition can be achieved. The guide indexng≃6.1 is consistent with theoretical estimates. In Pb1−xSnxTe DH devices, by corrugating the surface after all epitaxy is completed, a large coupling coefficient for Bragg reflection can be achieved because the last confining layer can be made very thin and the grating aspect ratio large.

ISSN:0003-6951    

DOI:10.1063/1.89057

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

By optical pumping, laser emission was achieved at 77 °K involving those nitrogen atoms in direct‐gap AlxGa1−xAs (x=0.39), which were incorporated by ion implantation. The energy of laser emission of nitrogen‐implanted material was about 14.4 meV lower than that of nitrogen‐free material.

ISSN:0003-6951    

DOI:10.1063/1.89058

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The occurrence of phosphorus antisite defect centers on cation sites in GaP, CdSiP2, and ZnGeP2has been demonstrated by electron spin resonance. The paramagnetic defect is identified by its characteristic hyperfine and ligand hyperfine interaction, representative for a31P31P4cluster. The possible role of the antisite lattice defect as a center of nonradiative recombination in LEC‐grown GaP is emphasized.

ISSN:0003-6951    

DOI:10.1063/1.89059

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Niobium‐germanium (Nb‐Ge) films which remain superconducting up to about 22.5 °K have been prepared using high‐rate (33–133 A˚/sec) electron‐beam codeposition. The presence of oxygen in the deposition chamber is necessary for stabilizing the high‐TcA15 phase. Analysis of Nb‐Ge films shows that oxygen extends, with some temperature dependence, the Ge‐rich range of theA15 phase with an accompanying decrease in the lattice constant. An amorphous component in the films is first detected below a deposition temperature of 800 °C. It increases rapidly at lower temperatures and becomes dominant at about 600 °C. TheA15 phase diagram was determined for the first time for temperatures below 875 °C.

ISSN:0003-6951    

DOI:10.1063/1.89060

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The first direct observation of the parametrically generated half‐harmonic voltage in a Josephson tunnel junction is reported. A microwave signal atf=17.25 GHz is applied to the junction dc current biased at zero voltage such that the Josephson plasma resonancefp=f/2. Under these conditions a large‐amplitude microwave signal is emitted atfpprovided the input power exceeds a threshold value. The results are compared to existing theory.

ISSN:0003-6951    

DOI:10.1063/1.89061

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The critical current of a commercial multifilamentary Nb3Sn conductor has been measured under the application of uniaxial tension at 4.2 K and following bending at room temperature. Significant reductions inJcare observed under uniaxial loading. Results are presented for a monolithic conductor manufactured by the bronze diffusion technique and for cable conductors formed by the tin‐dip technique.

ISSN:0003-6951    

DOI:10.1063/1.89062

出版商:AIP    

年代:1976

数据来源: AIP