摘要:

Laser Doppler velocimeters (LDV’s) are used as velocity microphones to measure sound pressure level in the range of 90–130 dB, spectral components, and two‐point correlation functions for acoustic noise source identification. Close agreement between LDV and microphone data is observed. Directional sensitivity and the ability to measure remotely make LDV’s useful tools for acoustic measurement where placement of any physical probe is difficult or undesirable, as in the diagnosis of jet noise.

ISSN:0003-6951    

DOI:10.1063/1.89102

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Population inversion for transitions in the VUV are predicted theoretically in laser‐produced plasmas. The calculations are based on a time‐dependent model that treats the excitation, ionization, and recombination dynamics of a dense argon plasma. Gains in excess of 103cm−1are obtained for the 3s‐3ptransition in carbonlike argon XIII for over 1000 psec.

ISSN:0003-6951    

DOI:10.1063/1.89103

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Average second‐harmonic power at 5.3 &mgr;m exceeding 0.75 W with a 17% power conversion efficiency has been obtained by pumping a CdGeAs2crystal, cooled to near 77 K, with a Q‐switched CO2laser. Average and peak conversion efficiencies of 21 and 30%, respectively, were achieved at a pulse rate of 1.5 kHz. In cw operation the crystal gave a second‐harmonic output of 73 mW with a conversion efficiency near 0.5%.

ISSN:0003-6951    

DOI:10.1063/1.89104

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Active mode locking of the 351‐nm XeF excimer laser is reported. Pulse durations of ⩽2 nsec were obtained using acousto‐optic gain modulation in a Blumlein‐drive laser. The pulsewidth is believed to be limited by the short time duration of the optical gain.

ISSN:0003-6951    

DOI:10.1063/1.89105

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Laser action of XeF has been obtained in atmospheric‐pressure mixtures of 0.1% NF3, 0.4% Xe, and 99.5% Ar with electron‐beam‐controlled discharge pumping. The mean discharge current and voltage were 75 A/cm2and 11 kV/cm, respectively, at 4 atm total pressure. The high‐energy E‐beam current was 12 A/cm2. Mechanisms for creating XeF* in a discharge are discussed. Physical processes which limit the intrinsic efficiency to 0.3% in the present device are also discussed.

ISSN:0003-6951    

DOI:10.1063/1.89106

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Backward Raman amplification in a fused‐silica fiber waveguide is studied using two dye lasers for its possible application as an amplifier and a pulse sharpening device. Greater than 90% of pump to signal conversion is observed together with a preferential amplification of the signal pulse front. Short pulse generation and complete pump depletion are also observed in a single dye laser pumped fiber Raman generator‐amplifier system.

ISSN:0003-6951    

DOI:10.1063/1.89107

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

p‐InP/n‐CdS heterodiodes electroluminesce under forward bias. In diodes prepared byinvacuogrowth of CdS layers on InP substrates, the spectrum is determined by recombination through deep interface states. Anneals at 500–600 °C shift the emission to energies close to the band gap of InP.

ISSN:0003-6951    

DOI:10.1063/1.89108

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Schottky barriers formed by the highly electronegative substance HgSe onn‐ZnS and onn‐ZnSe have been characterized by capacitance‐voltage and photoresponse measurements. The barriers are about 0.5 eV greater than Au barriers on thesen‐type substrates. HgSe contacts are stable under ambient conditions and are easily fabricated, making them attractive for device use.

ISSN:0003-6951    

DOI:10.1063/1.89109

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We suggest that the efficiency of a Schottky‐barrier (SB) solar cell could be subtantially increased (by as much as 2%) by making an optimum choice of the bulk series resistance (or the dopant concentration in the semiconductor) rather than minimizing it to zero. Thus we show that there exists an optimum nonzero bulk series resistance of SB solar cell for which the power conversion efficiency is maximum. For ann‐type GaAs/Au SB solar cell, this optimum series resistance is calculated to be 0.2 &OHgr; corresponding to a dopant concentration of 8×1013cm−3.

ISSN:0003-6951    

DOI:10.1063/1.89110

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Sheet‐resistivity and Hall‐effect measurements were made on C‐ion‐implanted GaAs after annealings at 600, 700, 800, or 900 °C. A doping efficiency of up to 50% was obtained in the 900 °C‐annealed sample which is much higher than the 2–8% reported previously. The electrical profile of this sample indicated that most of the implanted C became substitutional. The electrical compensation level, on the other hand, remained relatively high (0.3–0.6) throughout the profiling range and is responsible for the low doping efficiency obtained in the C‐implantedp‐type GaAs.

ISSN:0003-6951    

DOI:10.1063/1.89111

出版商:AIP    

年代:1976

数据来源: AIP