摘要:

The first use of a double‐pass geometry to enhance the conversion efficiency of a parametric nonlinear process in the tight‐focusing limit is reported. For third‐harmonic generation in liquid–CO‐O2mixtures using a CO2laser pump source, the observed enhancement is 2.5; elimination of reflection losses will result in an enhancement of 4. The double‐pass geometry has also been used to obtain accurate measurements of the wave‐vector mismatch &Dgr;kof the nonlinear medium.

ISSN:0003-6951    

DOI:10.1063/1.90221

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We report on an atomic thallium laser at 535.0 and 377.6 nm which is pumped by the photodissociation of TlI with the 193‐nm output of an ArF laser. High‐resolution Fabry‐Perot scans of the 535.0‐nm line have shown a structure in the laser spectrum which depends on the Tl inversion density. The energy efficiency for conversion of the pump into thallium laser emission has been measured to be 14±3%.

ISSN:0003-6951    

DOI:10.1063/1.90222

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Negative‐electron‐affinity (NEA) photocathodes are made possible by adding Cs and oxygen to the surface of Si or GaAs and other III‐V materials. In this work, the chemistry of the Cs‐O adlayer on GaAs is studied by following the Cs, Ga, and As core‐level shifts ath&ngr;=120 eV. The changes in binding energy for the Cs core levels were studied as a function of oxygen exposure. Oxygen was found to bind to As of GaAs for exposures above 10 L. These results are discussed in terms of the importance of Cs suboxides, in relation to the interfacial barriers which limit the ultimate photothreshold of NEA cathodes.

ISSN:0003-6951    

DOI:10.1063/1.90223

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A quasi‐steady‐state inversion and laser action in the near infrared in Pb+are shown to occur as a consequence of recombination and subsequent electron collisional thermalization within two ’’bands’’ of atomic energy levels. This demonstrates a mechanism for producing similar inversions at short wavelengths in a recombining plasma where the plasma density may be too high for radiative decay to establish an inversion.

ISSN:0003-6951    

DOI:10.1063/1.90224

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We have fabricated PbS1−xSexhomojunction diode lasers which operate up to 90 K cw and 140 K pulsed. Photon confinement was achieved by a carrier‐concentration profile rather than the usual compositional heterojunction. This results in a tuning range of 350 cm−1under cw operation.

ISSN:0003-6951    

DOI:10.1063/1.90225

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Rotation‐sensitive fiber‐ring interferometers have been demonstrated using balanced heterodyne phase‐detection techniques. Red He/Ne and infrared (GaAl)As lasers were employed with balanced elasto‐optic frequency shifters as sources. Rotation‐induced phase shift (Sagnac effect) was demonstrated using both single‐mode and multimode low‐loss fibers.

ISSN:0003-6951    

DOI:10.1063/1.90226

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Anodic iridium oxide films (AIROF’s) can be grown and operated on transparent substrates. Using SnO2‐coated glass as the substrate we can monitor large, rapid, and persistent variations of the light intensity transmitted through the AIROF. The voltammogram of the AIROF on SnO2‐coated glass is essentially identical to that of an AIROF on iridium. This proves that the electrochemistry producing the coloration does not involve the substrate.

ISSN:0003-6951    

DOI:10.1063/1.90227

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A Mach‐Zehnder interferometric waveguide modulator is demonstrated which simultaneously modulates both TE and TM modes. Two sets of electrodes are utilized to provide approximate independent control of vertical and horizontal field components across the channel waveguides. InZ‐X–cut LiNbO3this is shown to provide two polarization‐independent points of operation. With Ti‐diffused waveguides operated at 0.633 &mgr;m we obtained 90–95% modulation with applied voltages of 1.3 and 44 V and also with −8 and −36 V. Electrode design and alignment are shown to be important factors in device operation.

ISSN:0003-6951    

DOI:10.1063/1.90228

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The performance of an optical receiver depends heavily on the excess multiplication noise characteristics of the avalanche photodetector. The excess multiplication noise factor of an avalanche photodiode depends on the ratio of the electron and hole ionization coefficients. The ionization coefficients of 1.06‐&mgr;m photodiodes fabricated from Ga0.72Al0.28Sb have been measured. The results show a hole‐to‐electron ionization‐coefficient ratio of 2, which implies an excess gain noise factorFof 5.9 when the diode is operated at a gain of 10.

ISSN:0003-6951    

DOI:10.1063/1.90229

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Anodically oxidized Ta2O5surfaces were sputtered with 300–1800‐eV He+and Ar+ions. The surface composition was measured with AES and ISS. The results clearly show that the equilibrium surface composition depends on mass and energy of the primary ions. This composition is reversible for different masses or energies. A short discussion of these effects is given, including the characteristic fluence for obtaining equilibrium.

ISSN:0003-6951    

DOI:10.1063/1.90230

出版商:AIP    

年代:1978

数据来源: AIP